Interaction Models:
Ultra-High Energy Cosmic Rays & LHC data
Sergey Ostapchenko (NTNU, Trondheim)
ICRR (Tokyo), October 11, 2011[]

Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)

Air shower simulation procedures & hadronic interactions
qualitative picture
CR interaction models

Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)

Air shower simulation procedures & hadronic interactions
qualitative picture
CR interaction models

Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)

Air shower simulation procedures & hadronic interactions
qualitative picture
CR interaction models

Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)

Air shower simulation procedures & hadronic interactions
qualitative picture
CR interaction models

LHC data: impact on UHECR studies
comparison with model predictions
model retuning: impact on EAS predictions

Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)

Air shower simulation procedures & hadronic interactions
qualitative picture
CR interaction models

LHC data: impact on UHECR studies
comparison with model predictions
model retuning: impact on EAS predictions

Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)

Air shower simulation procedures & hadronic interactions
qualitative picture
CR interaction models

LHC data: impact on UHECR studies
comparison with model predictions
model retuning: impact on EAS predictions

Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)

Air shower simulation procedures & hadronic interactions
qualitative picture
CR interaction models

LHC data: impact on UHECR studies
comparison with model predictions
model retuning: impact on EAS predictions

UHECR composition puzzles

Outline(Ultra-)High Energy Cosmic Rays
CR spectrum
potential UHECR sources
detection methods: extensive air showers (EAS)

Air shower simulation procedures & hadronic interactions
qualitative picture
CR interaction models

LHC data: impact on UHECR studies
comparison with model predictions
model retuning: impact on EAS predictions

UHECR composition puzzles
Summary & prospects

High Energy Cosmic Rays

CR spectrum: over
>10 orders in energy

High Energy Cosmic Rays

CR spectrum: over
>10 orders in energy’knee’ at ∼ 3 × 1015
eV (effect of galactic
acceleration /propagation)

High Energy Cosmic Rays

CR spectrum: over
>10 orders in energy’knee’ at ∼ 3 × 1015
eV (effect of galactic
acceleration /propagation)’ankle’ at few × 1018
eV (galactic /extragalactictransition?)

High Energy Cosmic Rays
CR spectrum: over
>10 orders in energy’knee’ at ∼ 3 × 1015
eV (effect of galactic
acceleration /propagation)’ankle’ at few × 1018
eV (galactic /extragalactictransition?)
cutoff at ∼ 1020 eV(interaction withbackground γs?)

Ultra-High Energy Cosmic Rays (UHECR)
Potential UHECR sources – Hillas’s condition: CRs to be retainedin the source for sufficiently long time ⇒ Emax ∝ Bsource RsourceUltra-High Energy Cosmic Rays (UHECR)
Potential UHECR sources – Hillas’s condition: CRs to be retainedin the source for sufficiently long time ⇒ Emax ∝ Bsource Rsource

additional constaints– from energy losses
in the source⇒ UHECR sources –most likely
extragalactic
favorable option –Active Galactic
Nuclei (AGN)

Ultra-High Energy Cosmic Rays (UHECR)
Potential UHECR sources – Hillas’s condition: CRs to be retainedin the source for sufficiently long time ⇒ Emax ∝ Bsource Rsource

additional constaints– from energy losses
in the source⇒ UHECR sources –most likely
extragalactic
favorable option –Active Galactic
Nuclei (AGN)

Ultra-High Energy Cosmic Rays (UHECR)
Potential UHECR sources – Hillas’s condition: CRs to be retainedin the source for sufficiently long time ⇒ Emax ∝ Bsource Rsource

additional constaints– from energy losses
in the source⇒ UHECR sources –most likely
extragalactic
favorable option –Active Galactic
Nuclei (AGN)

Ultra-High Energy Cosmic Rays (UHECR)
nearest to us AGN – Centaurus A:
additional constaints– from energy losses
in the source⇒ UHECR sources –most likely
extragalactic
favorable option –Active Galactic
Nuclei (AGN)

Ultra-High Energy Cosmic Rays (UHECR)
nearest to us AGN – Centaurus A:
additional constaints– from energy losses
in the source⇒ UHECR sources –most likely
extragalactic
favorable option –Active Galactic
Nuclei (AGN)
CR acceleration
possible near theblack hole or in a
jet/lobe

AGNs already established as UHECR sources?
Pierre Auger Collaboration: correlation of UHECR arrival
directions with nearby AGNs at 3σ level [Science 318 (2007) 938]

correlation angularscale (3o ) – consistent
with expected
deflections for protons
considerable excess of
events in the directionof CenA

AGNs already established as UHECR sources?
Pierre Auger Collaboration: correlation of UHECR arrival
directions with nearby AGNs at 3σ level [Science 318 (2007) 938]

correlation angularscale (3o ) – consistent
with expected
deflections for protons
considerable excess of
events in the directionof CenA

AGNs already established as UHECR sources?
Pierre Auger Collaboration: correlation of UHECR arrival
directions with nearby AGNs at 3σ level [Science 318 (2007) 938]

correlation angularscale (3o ) – consistent
with expected
deflections for protons
considerable excess of
events in the directionof CenA

AGNs already established as UHECR sources?

however: correlation
signal weakened forlarger event sample
now: 2σ deviationfrom isotropic
distribution

AGNs already established as UHECR sources?

however: correlation
signal weakened forlarger event sample
now: 2σ deviationfrom isotropic
distribution

AGNs already established as UHECR sources?
Telescope Array Collaboration: 8 events out of 20 correlate with
AGNs [Sagawa, talk at TeVPA-2011]

AGNs already established as UHECR sources?
Telescope Array Collaboration: 8 events out of 20 correlate with
AGNs [Sagawa, talk at TeVPA-2011]⇒ consistent both with the isotropy and with the AGN
correlation hypothesis

Propagation in extragalactic space & GZK cutoff
why restrict oneself with nearby sources?

Propagation in extragalactic space & GZK cutoff
why restrict oneself with nearby sources?
the Universe is filled with 2.7K cosmological backgroundradiation (CMB)Propagation in extragalactic space & GZK cutoff
why restrict oneself with nearby sources?
the Universe is filled with 2.7K cosmological backgroundradiation (CMB)⇒ UHE protons quickly loose energy on CMB[Greisen, PRL 16 (1966); Zatsepin & Kuzmin, JETP Lett. 4(1966)]
p + π0p + γCMB →n + π+⇒ beyond ∼ 100 Mpc the Universe is opaque for UHECRPropagation in extragalactic space & GZK cutoff
why restrict oneself with nearby sources?
the Universe is filled with 2.7K cosmological backgroundradiation (CMB)⇒ UHE protons quickly loose energy on CMB[Greisen, PRL 16 (1966); Zatsepin & Kuzmin, JETP Lett. 4(1966)]
p + π0p + γCMB →n + π+⇒ beyond ∼ 100 Mpc the Universe is opaque for UHECR
for a uniform distribution of extragalactic CR sources results
in a spectral cutoff at E ∼ 5 × 1019 eV (GZK-cutoff)Propagation in extragalactic space & GZK cutoff
why restrict oneself with nearby sources?
the Universe is filled with 2.7K cosmological backgroundradiation (CMB)⇒ UHE protons quickly loose energy on CMB[Greisen, PRL 16 (1966); Zatsepin & Kuzmin, JETP Lett. 4(1966)]
p + π0p + γCMB →n + π+⇒ beyond ∼ 100 Mpc the Universe is opaque for UHECR
for a uniform distribution of extragalactic CR sources results
in a spectral cutoff at E ∼ 5 × 1019 eV (GZK-cutoff)in turn, UHE nuclei loose energy via photodisintegration on IR
photons: A + γ → (A − 1) + p/n ⇒ similar cutoff

Trans-GZK events & physics beyond the Standard Model?
Observation of trans-GZK events by the AGASA Collaboration[PRL 81 (1998)]

Trans-GZK events & physics beyond the Standard Model?
Observation of trans-GZK events by the AGASA Collaboration[PRL 81 (1998)]⇒ non-SM explanations of
UHECR origin:decays of cosmologicalrelics: topologicaldefects, superheavy
X-particles
Lorentz invarianceviolation’Z-birst’: annihilation of
UHE (anti-)neutrinos
with DM ones

Trans-GZK events & physics beyond the Standard Model?
Observation of trans-GZK events by the AGASA Collaboration[PRL 81 (1998)]⇒ non-SM explanations of
UHECR origin:decays of cosmologicalrelics: topologicaldefects, superheavy
X-particles
Lorentz invarianceviolation’Z-birst’: annihilation of
UHE (anti-)neutrinos
with DM ones

Trans-GZK events & physics beyond the Standard Model?
Observation of trans-GZK events by the AGASA Collaboration[PRL 81 (1998)]⇒ non-SM explanations of
UHECR origin:decays of cosmologicalrelics: topologicaldefects, superheavy
X-particles
Lorentz invarianceviolation’Z-birst’: annihilation of
UHE (anti-)neutrinos
with DM ones

Trans-GZK events & physics beyond the Standard Model?
Observation of trans-GZK events by the AGASA Collaboration[PRL 81 (1998)]⇒ non-SM explanations of
UHECR origin:decays of cosmologicalrelics: topologicaldefects, superheavy
X-particles
Lorentz invarianceviolation’Z-birst’: annihilation of
UHE (anti-)neutrinos
with DM ones

Trans-GZK events & physics beyond the Standard Model?

Now: UHECR cutoff – observed by 3 independent collaborations

Trans-GZK events & physics beyond the Standard Model?

Flux*E3/1024 (eV2 m-2 s-1 sr-1)

Now: UHECR cutoff – observed by 3 independent collaborations
10

HiRes-2 Monocular
HiRes-1 Monocular
AGASA

1

17

17.5

18

18.5

19

19.5

20

20.5

21

log10(E (eV))

HiRes Collaboration[PRL 100 (2008)]:
GZK-cutoff observedwith 5σ significanceTrans-GZK events & physics beyond the Standard Model?
Now: UHECR cutoff – observed by 3 independent collaborations
log (E/eV)
10

E 3 J(E) [km-2 yr-1 sr -1 eV 2]

18

18.5

19

19.5

20

20.5
σsys(E)=22%

1038

HiRes Collaboration[PRL 100 (2008)]:
GZK-cutoff observedwith 5σ significance

HiRes

1037

Auger
power laws
power laws + smooth function
1018

1019

1020

Energy [eV]

Pierre Auger Collab.
[PRL 101 (2008)]:
cutoff observed with
6σ significanceTrans-GZK events & physics beyond the Standard Model?
Now: UHECR cutoff – observed by 3 independent collaborations
HiRes Collaboration[PRL 100 (2008)]:
GZK-cutoff observedwith 5σ significance
Pierre Auger Collab.
[PRL 101 (2008)]:
cutoff observed with
6σ significance
Telescope Array Collab.
[Stokes, ICRC-2011]:
cutoff observed with
3.9σ significanceTrans-GZK events & physics beyond the Standard Model?
Now: UHECR cutoff – observed by 3 independent collaborations
HiRes Collaboration[PRL 100 (2008)]:
GZK-cutoff observedwith 5σ significance
Pierre Auger Collab.
[PRL 101 (2008)]:
cutoff observed with
6σ significancetrans-GZK story - finally over

Telescope Array Collab.
[Stokes, ICRC-2011]:
cutoff observed with
3.9σ significanceUHECR cutoff: GZK or not?
UHECR also loose energy via e+ e− -pair production on CMB:
p + γ → p + e+ + e−

UHECR cutoff: GZK or not?
UHECR also loose energy via e+ e− -pair production on CMB:
p + γ → p + e+ + e−
if UHECR are protons: spectral ’dip’ will be produced

UHECR cutoff: GZK or not?
UHECR also loose energy via e+ e− -pair production on CMB:
p + γ → p + e+ + e−
if UHECR are protons: spectral ’dip’ will be produced’dip’ model for galactic-extragalactic transition[Berezinsky & Grigor’eva, A&A 199 (1988)]
transition takes place well before the ’ankle’
observed CR ’ankle’ ≡ pair production ’dip’energy-relation between GZK cutoff and the ’ankle’ (=’dip’)– well reproduced

UHECR cutoff: GZK or not?
UHECR also loose energy via e+ e− -pair production on CMB:
p + γ → p + e+ + e−
if UHECR are protons: spectral ’dip’ will be produced’dip’ model for galactic-extragalactic transition[Berezinsky & Grigor’eva, A&A 199 (1988)]
transition takes place well before the ’ankle’
observed CR ’ankle’ ≡ pair production ’dip’energy-relation between GZK cutoff and the ’ankle’ (=’dip’)– well reproduced

UHECR cutoff: GZK or not?
UHECR also loose energy via e+ e− -pair production on CMB:
p + γ → p + e+ + e−
if UHECR are protons: spectral ’dip’ will be produced’dip’ model for galactic-extragalactic transition[Berezinsky & Grigor’eva, A&A 199 (1988)]
transition takes place well before the ’ankle’
observed CR ’ankle’ ≡ pair production ’dip’energy-relation between GZK cutoff and the ’ankle’ (=’dip’)– well reproduced

UHECR cutoff: GZK or not?
UHECR also loose energy via e+ e− -pair production on CMB:
p + γ → p + e+ + e−
if UHECR are protons: spectral ’dip’ will be produced’dip’ model for galactic-extragalactic transition[Berezinsky & Grigor’eva, A&A 199 (1988)]
transition takes place well before the ’ankle’
observed CR ’ankle’ ≡ pair production ’dip’energy-relation between GZK cutoff and the ’ankle’ (=’dip’)– well reproduced

UHECR cutoff: GZK or not?
UHECR also loose energy via e+ e− -pair production on CMB:
p + γ → p + e+ + e−
if UHECR are protons: spectral ’dip’ will be produced’dip’ model for galactic-extragalactic transition[Berezinsky & Grigor’eva, A&A 199 (1988)]
transition takes place well before the ’ankle’
observed CR ’ankle’ ≡ pair production ’dip’energy-relation between GZK cutoff and the ’ankle’ (=’dip’)– well reproduced

if UHECR = Fe: no pronounced ’dip’⇒ galactic-extragalactic transition – at the ’ankle’

UHECR cutoff: GZK or not?
UHECR also loose energy via e+ e− -pair production on CMB:
p + γ → p + e+ + e−
if UHECR are protons: spectral ’dip’ will be produced’dip’ model for galactic-extragalactic transition[Berezinsky & Grigor’eva, A&A 199 (1988)]
transition takes place well before the ’ankle’
observed CR ’ankle’ ≡ pair production ’dip’energy-relation between GZK cutoff and the ’ankle’ (=’dip’)– well reproduced

if UHECR = Fe: no pronounced ’dip’⇒ galactic-extragalactic transition – at the ’ankle’

UHECR cutoff: GZK or not?
UHECR also loose energy via e+ e− -pair production on CMB:
p + γ → p + e+ + e−
if UHECR are protons: spectral ’dip’ will be produced’dip’ model for galactic-extragalactic transition[Berezinsky & Grigor’eva, A&A 199 (1988)]
transition takes place well before the ’ankle’
observed CR ’ankle’ ≡ pair production ’dip’energy-relation between GZK cutoff and the ’ankle’ (=’dip’)– well reproduced

if UHECR = Fe: no pronounced ’dip’⇒ galactic-extragalactic transition – at the ’ankle’⇒ measurements of CR composition – key to the UHECR puzzle

Extensive Air Shower (EAS) techniques of CR detection
observations of nuclear-e/m cascades induced by CR particles:Extensive Air Shower (EAS) techniques of CR detection

ground-based observations (= thick target experiments)
primary CR energy ⇐⇒ charged particle density at groundCR composition ⇐⇒ muon density at groundExtensive Air Shower (EAS) techniques of CR detection

ground-based observations (= thick target experiments)
primary CR energy ⇐⇒ charged particle density at groundCR composition ⇐⇒ muon density at groundExtensive Air Shower (EAS) techniques of CR detection

ground-based observations (= thick target experiments)
primary CR energy ⇐⇒ charged particle density at groundCR composition ⇐⇒ muon density at groundExtensive Air Shower (EAS) techniques of CR detection

ground-based observations (= thick target experiments)
primary CR energy ⇐⇒ charged particle density at groundCR composition ⇐⇒ muon density at groundmeasurements of EAS fluorescence light
primary CR energy ⇐⇒ integrated light
CR composition ⇐⇒ shower maximum position Xmax

Extensive Air Shower (EAS) techniques of CR detection

ground-based observations (= thick target experiments)
primary CR energy ⇐⇒ charged particle density at groundCR composition ⇐⇒ muon density at groundmeasurements of EAS fluorescence light
primary CR energy ⇐⇒ integrated light
CR composition ⇐⇒ shower maximum position Xmax

Extensive Air Shower (EAS) techniques of CR detection

ground-based observations (= thick target experiments)
primary CR energy ⇐⇒ charged particle density at groundCR composition ⇐⇒ muon density at groundmeasurements of EAS fluorescence light
primary CR energy ⇐⇒ integrated light
CR composition ⇐⇒ shower maximum position Xmax

Extensive air shower development
EAS development –driven by interactionsof primary / ’leading’secondary particles⇒ hadronic cascade= EAS backbone
secondary cascades –well averaged
observables used for CR
composition studies –most sensitive tohadronic physics
e.g. Xmax : to σinel
p−air andinel
to ’inelasticity’ Kp−airch√Nµ : to Nπ−airE∼ E0Extensive air shower development
EAS development –driven by interactionsof primary / ’leading’secondary particles⇒ hadronic cascade= EAS backbone
secondary cascades –well averaged
observables used for CR
composition studies –most sensitive tohadronic physics
e.g. Xmax : to σinel
p−air andinel
to ’inelasticity’ Kp−airch√Nµ : to Nπ−airE∼ E0Extensive air shower development
EAS development –driven by interactionsof primary / ’leading’secondary particles⇒ hadronic cascade= EAS backbone
secondary cascades –well averaged
observables used for CR
composition studies –most sensitive tohadronic physics
e.g. Xmax : to σinel
p−air andinel
to ’inelasticity’ Kp−airch√Nµ : to Nπ−airE∼ E0Extensive air shower development
EAS development –driven by interactionsof primary / ’leading’secondary particles⇒ hadronic cascade= EAS backbone
secondary cascades –well averaged
observables used for CR
composition studies –most sensitive tohadronic physics
e.g. Xmax : to σinel
p−air andinel
to ’inelasticity’ Kp−airch√Nµ : to Nπ−airE∼ E0Extensive air shower development
EAS development –driven by interactionsof primary / ’leading’secondary particles⇒ hadronic cascade= EAS backbone
secondary cascades –well averaged
observables used for CR
composition studies –most sensitive tohadronic physics
e.g. Xmax : to σinel
p−air andinel
to ’inelasticity’ Kp−airch√Nµ : to Nπ−airE∼ E0Extensive air shower development
EAS development –driven by interactionsof primary / ’leading’secondary particles⇒ hadronic cascade= EAS backbone
secondary cascades –well averaged
observables used for CR
composition studies –most sensitive tohadronic physics
e.g. Xmax : to σinel
p−air andinel
to ’inelasticity’ Kp−airch√Nµ : to Nπ−airE∼ E0Extensive air shower development

CR composition studies with fluorescence detectors (FD)most sensitive to primary particle interactions (via Xmax )⇒ suffer from uncertainties of σinel
p−air

E0

inel
, Kp−airE0

seeing it optimistic: probe proton-air (nucleus-air) interactions
at maximal energies (up to ∼ 1021 eV)Extensive air shower development

CR composition studies with fluorescence detectors (FD)most sensitive to primary particle interactions (via Xmax )⇒ suffer from uncertainties of σinel
p−air

E0

inel
, Kp−airE0

seeing it optimistic: probe proton-air (nucleus-air) interactions
at maximal energies (up to ∼ 1021 eV)Extensive air shower development

CR composition studies with fluorescence detectors (FD)most sensitive to primary particle interactions (via Xmax )⇒ suffer from uncertainties of σinel
p−air

E0

inel
, Kp−airE0

seeing it optimistic: probe proton-air (nucleus-air) interactions
at maximal energies (up to ∼ 1021 eV)Extensive air shower development
CR composition studies with fluorescence detectors (FD)most sensitive to primary particle interactions (via Xmax )⇒ suffer from uncertainties of σinel
p−air

E0

inel
, Kp−airE0

seeing it optimistic: probe proton-air (nucleus-air) interactions
at maximal energies (up to ∼ 1021 eV)

CR composition studies with ground-based detectors (SD)most sensitive to interactions of secondary pions (also√ kaons& (anti-)nucleons) at intermediate energies (E ∼ E0 )

Nucleus-induced air showers & superposition model
For average (only!) air shower characteristics: A−induced EAS ofenergy E – equivalent to A proton-induced showers of energy E/Ainel
N of ’wounded’ nucleons per collision: hνA i = A σinel
p−air /σA−air(valid up to target diffraction)
inel
nuclear m.f.p. is σinel
p−air /σA−air shorter
σinel

p−air
however, each nucleon interacts with probability: wint = σinel

A−airNucleus-induced air showers & superposition model
For average (only!) air shower characteristics: A−induced EAS ofenergy E – equivalent to A proton-induced showers of energy E/Ainel
N of ’wounded’ nucleons per collision: hνA i = A σinel
p−air /σA−air(valid up to target diffraction)
inel
nuclear m.f.p. is σinel
p−air /σA−air shorter
σinel

p−air
however, each nucleon interacts with probability: wint = σinel

A−airNucleus-induced air showers & superposition model
For average (only!) air shower characteristics: A−induced EAS ofenergy E – equivalent to A proton-induced showers of energy E/Ainel
N of ’wounded’ nucleons per collision: hνA i = A σinel
p−air /σA−air(valid up to target diffraction)
inel
nuclear m.f.p. is σinel
p−air /σA−air shorter
σinel

p−air
however, each nucleon interacts with probability: wint = σinel

A−airNucleus-induced air showers & superposition model
For average (only!) air shower characteristics: A−induced EAS ofenergy E – equivalent to A proton-induced showers of energy E/Ainel
N of ’wounded’ nucleons per collision: hνA i = A σinel
p−air /σA−air(valid up to target diffraction)
inel
nuclear m.f.p. is σinel
p−air /σA−air shorter
σinel

p−air
however, each nucleon interacts with probability: wint = σinel

A−airNucleus-induced air showers & superposition model
For average (only!) air shower characteristics: A−induced EAS ofenergy E – equivalent to A proton-induced showers of energy E/Ainel
N of ’wounded’ nucleons per collision: hνA i = A σinel
p−air /σA−air(valid up to target diffraction)
inel
nuclear m.f.p. is σinel
p−air /σA−air shorter
σinel

p−air
however, each nucleon interacts with probability: wint = σinel

A−air

A (E)i ≃ hX p (E/A)i;⇒ hXmaxmax

A (E)i ≃ A · hN p (E/A)i
hNe/µ
e/µ

Nucleus-induced air showers & superposition model
For average (only!) air shower characteristics: A−induced EAS ofenergy E – equivalent to A proton-induced showers of energy E/Ainel
N of ’wounded’ nucleons per collision: hνA i = A σinel
p−air /σA−air(valid up to target diffraction)
inel
nuclear m.f.p. is σinel
p−air /σA−air shorter
σinel

p−air
however, each nucleon interacts with probability: wint = σinel

A−air

A (E)i ≃ hX p (E/A)i;⇒ hXmaxmaxp

A (E)i ≃ A · hN p (E/A)i
hNe/µ
e/µ
p

hXmax (E)i ≃ const + ER ln E, ER ≡ dhXmax (E)i/dE;phNe/µ (E/A)i ∝ Eαe/µ , αe ≃ 1.1, αµ ≃ 0.9

Nucleus-induced air showers & superposition model
For average (only!) air shower characteristics: A−induced EAS ofenergy E – equivalent to A proton-induced showers of energy E/Ainel
N of ’wounded’ nucleons per collision: hνA i = A σinel
p−air /σA−air(valid up to target diffraction)
inel
nuclear m.f.p. is σinel
p−air /σA−air shorter
σinel

p−air
however, each nucleon interacts with probability: wint = σinel

A−air

A (E)i ≃ hX p (E/A)i;⇒ hXmaxmaxp

A (E)i ≃ A · hN p (E/A)i
hNe/µ
e/µ
p

hXmax (E)i ≃ const + ER ln E, ER ≡ dhXmax (E)i/dE;phNe/µ (E/A)i ∝ Eαe/µ , αe ≃ 1.1, αµ ≃ 0.9p

A (E)i ≃ hX
⇒ hXmaxmax (E)i − ER ln AppAhNe (E)i ≃ hNe (E)i A0.1 ; hNµA (E)i ≃ hNµ (E)i A−0.1– nucleus-induced air showers reach their maxima earlier,have less e± and more muons

UHECR composition from Xmax observations

EAS maximum position Xmax – the key to the UHECR compositionUHECR composition from Xmax observations
EAS maximum position Xmax – the key to the UHECR composition
850
QGSJET02

spectatular results from
HiRes Collab. [PRL (2005);
PRL (2010)]: p-dominatedcomposition above 1018 eV

<X

max

2

> [g/cm ]

800
750
700

pro

ton

650
HiRes/MIA

600
550

iro

1017

n

HiRes 2009

1018

1019
E [eV]

strong support for the ’dip’
model: transition fromgalactic Fe to extragalactic
p component at 1017 eV

UHECR composition from Xmax observations
EAS maximum position Xmax – the key to the UHECR composition
850
QGSJET02

spectatular results from
HiRes Collab. [PRL (2005);
PRL (2010)]: p-dominatedcomposition above 1018 eV

<X

max

2

> [g/cm ]

800
750
700

pro

ton

650
HiRes/MIA

600
550

iro

1017

n

HiRes 2009

1018

1019
E [eV]

strong support for the ’dip’
model: transition fromgalactic Fe to extragalactic
p component at 1017 eV

UHECR composition from Xmax observations
EAS maximum position Xmax – the key to the UHECR composition

spectatular results from
HiRes Collab. [PRL (2005);
PRL (2010)]: p-dominatedcomposition above 1018 eV
supported by data of
Telescope Array Collab.
[Tameda, ICRC-2011]

UHECR composition from Xmax observations
EAS maximum position Xmax – the key to the UHECR composition
Pierre Auger Collab.:change from light to heavy
CRs above 1019 eV[PRL (2010); Facal San
Luis, ICRC-2011]
interpretation of data –strongly model-dependent!

UHECR composition from Xmax observations
EAS maximum position Xmax – the key to the UHECR composition
Pierre Auger Collab.:change from light to heavy
CRs above 1019 eV[PRL (2010); Facal San
Luis, ICRC-2011]
interpretation of data –strongly model-dependent!

UHECR composition from Xmax observations
EAS maximum position Xmax – the key to the UHECR composition
Pierre Auger Collab.:change from light to heavy
CRs above 1019 eV[PRL (2010); Facal San
Luis, ICRC-2011]
interpretation of data –strongly model-dependent!
is it possible to reduce
model-dependence?!

UHECR composition from Xmax observations
EAS maximum position Xmax – the key to the UHECR composition
Pierre Auger Collab.:change from light to heavy
CRs above 1019 eV[PRL (2010); Facal San
Luis, ICRC-2011]
interpretation of data –strongly model-dependent!
is it possible to reduce
model-dependence?!
yes, by studying shower fluctuations, e.g. RMS(Xmax )[Aloisio, Berezinsky, Blasi & SO, PRD 77 (2008)]

UHECR composition from RMS(Xmax)?
RMS(Xmax ) for proton-induced showers
mainly dominated by m.f.p. λp ∝ 1/σinel
p−airalso sensitive to the collision geometry: large ’stopping power’(Kinel ) for small b, small Kinel for large b

UHECR composition from RMS(Xmax)?
RMS(Xmax ) for proton-induced showers
mainly dominated by m.f.p. λp ∝ 1/σinel
p−airalso sensitive to the collision geometry: large ’stopping power’(Kinel ) for small b, small Kinel for large b

UHECR composition from RMS(Xmax)?
RMS(Xmax ) for proton-induced showers
mainly dominated by m.f.p. λp ∝ 1/σinel
p−airalso sensitive to the collision geometry: large ’stopping power’(Kinel ) for small b, small Kinel for large b

UHECR composition from RMS(Xmax)?
RMS(Xmax ) for proton-induced showers
mainly dominated by m.f.p. λp ∝ 1/σinel
p−airalso sensitive to the collision geometry: large ’stopping power’(Kinel ) for small b, small Kinel for large b

RMS(Xmax ) for nucleus-induced showers
mainly dominated by the collision geometry:(more ’participants’ for central collisions)sensitive to nuclear fragmentation (up to factor of 2 difference
for RMS(Xmax ) [Kalmykov & SO, Phys. At. Nucl. 56 (1993)]
NB: superposition model inapplicableUHECR composition from RMS(Xmax)?
RMS(Xmax ) for proton-induced showers
mainly dominated by m.f.p. λp ∝ 1/σinel
p−airalso sensitive to the collision geometry: large ’stopping power’(Kinel ) for small b, small Kinel for large b

RMS(Xmax ) for nucleus-induced showers
mainly dominated by the collision geometry:(more ’participants’ for central collisions)sensitive to nuclear fragmentation (up to factor of 2 difference
for RMS(Xmax ) [Kalmykov & SO, Phys. At. Nucl. 56 (1993)]
NB: superposition model inapplicableUHECR composition from RMS(Xmax)?
RMS(Xmax ) for proton-induced showers
mainly dominated by m.f.p. λp ∝ 1/σinel
p−airalso sensitive to the collision geometry: large ’stopping power’(Kinel ) for small b, small Kinel for large b

RMS(Xmax ) for nucleus-induced showers
mainly dominated by the collision geometry:(more ’participants’ for central collisions)sensitive to nuclear fragmentation (up to factor of 2 difference
for RMS(Xmax ) [Kalmykov & SO, Phys. At. Nucl. 56 (1993)]
NB: superposition model inapplicableUHECR composition from RMS(Xmax)?
RMS(Xmax ) for proton-induced showers
mainly dominated by m.f.p. λp ∝ 1/σinel
p−airalso sensitive to the collision geometry: large ’stopping power’(Kinel ) for small b, small Kinel for large b

RMS(Xmax ) for nucleus-induced showers
mainly dominated by the collision geometry:(more ’participants’ for central collisions)sensitive to nuclear fragmentation (up to factor of 2 difference
for RMS(Xmax ) [Kalmykov & SO, Phys. At. Nucl. 56 (1993)]
NB: superposition model inapplicableUHECR composition from RMS(Xmax)

RMS(Xmax ) measured by
the Pierre Auger Collab.
[PRL (2010); Facal San
Luis, ICRC-2011]
model-dependence strongly
reducedbut: almost pure Fe at thehighest energies?!

UHECR composition from RMS(Xmax)

RMS(Xmax ) measured by
the Pierre Auger Collab.
[PRL (2010); Facal San
Luis, ICRC-2011]
model-dependence strongly
reducedbut: almost pure Fe at thehighest energies?!

UHECR composition from RMS(Xmax)

RMS(Xmax ) measured by
the Pierre Auger Collab.
[PRL (2010); Facal San
Luis, ICRC-2011]
model-dependence strongly
reducedbut: almost pure Fe at thehighest energies?!

UHECR composition from muon component?

Alternative approach – study of muon densities at groundUHECR composition from muon component?
Alternative approach – study of muon densities at ground
Pierre Auger Collab.: strong muon excess observed comparedto model predictions! [Rodriguez, ICRC-2011]

UHECR composition from muon component?
Alternative approach – study of muon densities at ground
Pierre Auger Collab.: strong muon excess observed comparedto model predictions! [Rodriguez, ICRC-2011]

may be UHECR are gold nuclei?!

UHECR composition from muon component?
Alternative approach – study of muon densities at ground
Pierre Auger Collab.: strong muon excess observed comparedto model predictions! [Rodriguez, ICRC-2011]

may be UHECR are gold nuclei?!
highly unlikely, rather CR interaction models should be wrong

High energy interactions: qualitative picture

multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction[picture from R. Engel]

High energy interactions: qualitative picture

multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction[picture from R. Engel]

High energy interactions: qualitative picture

multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction[picture from R. Engel]

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’soft’ (all |q2 | < Q20 ∼ 1 GeV2 )large effective area (∆b2 ∼ 1/|q2 |)slow energy rise / low parton density⇒ dominant at low energies & large b

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’soft’ (all |q2 | < Q20 ∼ 1 GeV2 )large effective area (∆b2 ∼ 1/|q2 |)slow energy rise / low parton density⇒ dominant at low energies & large b

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’soft’ (all |q2 | < Q20 ∼ 1 GeV2 )large effective area (∆b2 ∼ 1/|q2 |)slow energy rise / low parton density⇒ dominant at low energies & large b

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’soft’ (all |q2 | < Q20 ∼ 1 GeV2 )large effective area (∆b2 ∼ 1/|q2 |)slow energy rise / low parton density⇒ dominant at low energies & large b

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’hard’ (all |q2 | ≫ Q20 )small effective area
rapid energy rise / high parton density⇒ important for dedicated QCD studies

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’hard’ (all |q2 | ≫ Q20 )small effective area
rapid energy rise / high parton density⇒ important for dedicated QCD studies

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’hard’ (all |q2 | ≫ Q20 )small effective area
rapid energy rise / high parton density⇒ important for dedicated QCD studies

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’hard’ (all |q2 | ≫ Q20 )small effective area
rapid energy rise / high parton density⇒ important for dedicated QCD studies

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’semihard’ (some |q2 | > Q20 )combines ’soft’ & hard parton evolution⇒ large area / rapid energy rise / high density
dominant at high energies / wide b-range

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’semihard’ (some |q2 | > Q20 )combines ’soft’ & hard parton evolution⇒ large area / rapid energy rise / high density
dominant at high energies / wide b-range

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’semihard’ (some |q2 | > Q20 )combines ’soft’ & hard parton evolution⇒ large area / rapid energy rise / high density
dominant at high energies / wide b-range

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

single cascade may be ’semihard’ (some |q2 | > Q20 )combines ’soft’ & hard parton evolution⇒ large area / rapid energy rise / high density
dominant at high energies / wide b-range

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

general cascade contribution contains all
soft processes → σtot , σinel , diffraction
hard processes → multiplicity’black disk’ broadens with energy ⇒ hard
processes – more and more important

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

general cascade contribution contains all
soft processes → σtot , σinel , diffraction
hard processes → multiplicity’black disk’ broadens with energy ⇒ hard
processes – more and more important

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

general cascade contribution contains all
soft processes → σtot , σinel , diffraction
hard processes → multiplicity’black disk’ broadens with energy ⇒ hard
processes – more and more important

High energy interactions: qualitative picture
multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction

general cascade contribution contains all
soft processes → σtot , σinel , diffraction
hard processes → multiplicity’black disk’ broadens with energy ⇒ hard
processes – more and more important

High energy interactions: qualitative picture

multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction
NB: separation between soft & hard processes – artificial
physics changes smoothly from small to large q2
general cascade contribution contains all
parton density decreases gradually from small to large bsoft processes → σtot , σinel , diffraction
hard processes → multiplicity’black disk’ broadens with energy ⇒ hard

High energy interactions: qualitative picture

multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction
NB: separation between soft & hard processes – artificial
physics changes smoothly from small to large q2
general cascade contribution contains all
parton density decreases gradually from small to large bsoft processes → σtot , σinel , diffraction
hard processes → multiplicity’black disk’ broadens with energy ⇒ hard

High energy interactions: qualitative picture

multiple scattering picture: many
parton cascades develop in parallel
generally required for unitarity
allows to explain multiple (mini-)jetproduction
NB: separation between soft & hard processes – artificial
physics changes smoothly from small to large q2
general cascade contribution contains all
parton density decreases gradually from small to large bsoft processes → σtot , σinel , diffraction
hard processes → multiplicity’black disk’ broadens with energy ⇒ hard

High energy interactions: parton shadowing / saturation

When parton density becomes high(high energy & small b):
parton cascades strongly overlap
and interact with each other⇒ shadowing effects(slower rise of parton density)
saturation: parton production– compensated by their fusion

High energy interactions: parton shadowing / saturation

When parton density becomes high(high energy & small b):
parton cascades strongly overlap
and interact with each other⇒ shadowing effects(slower rise of parton density)
saturation: parton production– compensated by their fusion

High energy interactions: parton shadowing / saturation

When parton density becomes high(high energy & small b):
parton cascades strongly overlap
and interact with each other⇒ shadowing effects(slower rise of parton density)
saturation: parton production– compensated by their fusion

High energy interactions: parton shadowing / saturation

When parton density becomes high(high energy & small b):
parton cascades strongly overlap
and interact with each other⇒ shadowing effects(slower rise of parton density)
saturation: parton production– compensated by their fusion

High energy interactions: parton shadowing / saturation
When parton density becomes high(high energy & small b):
parton cascades strongly overlap
and interact with each other⇒ shadowing effects(slower rise of parton density)
saturation: parton production– compensated by their fusion
For very high parton density’soft’ (low pt ) partons – fully saturated
population dominated by ’hard’ partons⇒ very dense parton system can be
described perturbatively

High energy interactions: parton shadowing / saturation
When parton density becomes high(high energy & small b):
parton cascades strongly overlap
and interact with each other⇒ shadowing effects(slower rise of parton density)
saturation: parton production– compensated by their fusion
For very high parton density’soft’ (low pt ) partons – fully saturated
population dominated by ’hard’ partons⇒ very dense parton system can be
described perturbatively

High energy interactions: parton shadowing / saturation
When parton density becomes high(high energy & small b):
parton cascades strongly overlap
and interact with each other⇒ shadowing effects(slower rise of parton density)
saturation: parton production– compensated by their fusion
For very high parton density’soft’ (low pt ) partons – fully saturated
population dominated by ’hard’ partons⇒ very dense parton system can be
described perturbatively

High energy interactions: parton shadowing / saturation
When parton density becomes high(high energy & small b):
parton cascades strongly overlap
and interact with each other⇒ shadowing effects(slower rise of parton density)
saturation: parton production– compensated by their fusion
For very high parton density’soft’ (low pt ) partons – fully saturated
population dominated by ’hard’ partons⇒ very dense parton system can be
described perturbatively

CR interaction models
similar physics content for all MC generators used in CR field:
multiple scattering
soft & hard processes
nonlinear effects, e.g. parton shadowing (not in all models)CR interaction models
similar physics content for all MC generators used in CR field:
multiple scattering
soft & hard processes
nonlinear effects, e.g. parton shadowing (not in all models)CR interaction models
similar physics content for all MC generators used in CR field:
multiple scattering
soft & hard processes
nonlinear effects, e.g. parton shadowing (not in all models)CR interaction models
similar physics content for all MC generators used in CR field:
multiple scattering
soft & hard processes
nonlinear effects, e.g. parton shadowing (not in all models)CR interaction models
similar physics content for all MC generators used in CR field:
multiple scattering
soft & hard processes
nonlinear effects, e.g. parton shadowing (not in all models)representative models:
QGSJET (Kalmykov & SO, 1993–1997)
SIBYLL 1.7/2.1 (Ahn, Engel, Gaisser, Lipari & Stanev,
1994/1999)
QGSJET II-03/04 (SO, 2006/2011)
EPOS (Liu, Pierog & Werner, 2006-2011)

CR interaction models
similar physics content for all MC generators used in CR field:
multiple scattering
soft & hard processes
nonlinear effects, e.g. parton shadowing (not in all models)representative models:
QGSJET (Kalmykov & SO, 1993–1997)
SIBYLL 1.7/2.1 (Ahn, Engel, Gaisser, Lipari & Stanev,
1994/1999)
QGSJET II-03/04 (SO, 2006/2011)
EPOS (Liu, Pierog & Werner, 2006-2011)

all the models based on similar ideas / qualitative approaches

CR interaction models
similar physics content for all MC generators used in CR field:
multiple scattering
soft & hard processes
nonlinear effects, e.g. parton shadowing (not in all models)representative models:
QGSJET (Kalmykov & SO, 1993–1997)
SIBYLL 1.7/2.1 (Ahn, Engel, Gaisser, Lipari & Stanev,
1994/1999)
QGSJET II-03/04 (SO, 2006/2011)
EPOS (Liu, Pierog & Werner, 2006-2011)

all the models based on similar ideas / qualitative approaches
differ in implementations, theory input, etc. ⇒ in predictions

CR interaction models
similar physics content for all MC generators used in CR field:
multiple scattering
soft & hard processes
nonlinear effects, e.g. parton shadowing (not in all models)representative models:
QGSJET (Kalmykov & SO, 1993–1997)
SIBYLL 1.7/2.1 (Ahn, Engel, Gaisser, Lipari & Stanev,
1994/1999)
QGSJET II-03/04 (SO, 2006/2011)
EPOS (Liu, Pierog & Werner, 2006-2011)

all the models based on similar ideas / qualitative approaches
differ in implementations, theory input, etc. ⇒ in predictions
model updates / cross checks with new data - necessaryModel implementations of parton shadowing / saturation

not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

Model implementations of parton shadowing / saturation

not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

Model implementations of parton shadowing / saturation

not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

Model implementations of parton shadowing / saturation

not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

Model implementations of parton shadowing / saturation

not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

Model implementations of parton shadowing / saturation

not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

EPOS: via parametrized weights for different configurations
energy- & b-dependent treatment
however: weak predictive powerModel implementations of parton shadowing / saturation

not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

EPOS: via parametrized weights for different configurations
energy- & b-dependent treatment
however: weak predictive powerModel implementations of parton shadowing / saturation

not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

EPOS: via parametrized weights for different configurations
energy- & b-dependent treatment
however: weak predictive powerModel implementations of parton shadowing / saturation
not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

EPOS: via parametrized weights for different configurations
energy- & b-dependent treatment
however: weak predictive power

QGSJET-II: full resummation of
Pomeron-Pomeron interaction diagrams
fully dynamical treatment
but: based on ’soft’ Pomeron coupling⇒ no evolution for the saturation scale

...

...

Model implementations of parton shadowing / saturation
not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

EPOS: via parametrized weights for different configurations
energy- & b-dependent treatment
however: weak predictive power

QGSJET-II: full resummation of
Pomeron-Pomeron interaction diagrams
fully dynamical treatment
but: based on ’soft’ Pomeron coupling⇒ no evolution for the saturation scale

...

...

Model implementations of parton shadowing / saturation
not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

EPOS: via parametrized weights for different configurations
energy- & b-dependent treatment
however: weak predictive power

QGSJET-II: full resummation of
Pomeron-Pomeron interaction diagrams
fully dynamical treatment
but: based on ’soft’ Pomeron coupling⇒ no evolution for the saturation scale

...

...

Model implementations of parton shadowing / saturation
not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

EPOS: via parametrized weights for different configurations
energy- & b-dependent treatment
however: weak predictive power

QGSJET-II: full resummation of
Pomeron-Pomeron interaction diagrams
fully dynamical treatment
but: based on ’soft’ Pomeron coupling⇒ no evolution for the saturation scale

...

...

Model implementations of parton shadowing / saturation
not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

EPOS: via parametrized weights for different configurations
energy- & b-dependent treatment
however: weakpredictive
power models
But also technicaldifferences
betweentreatment of hadronic ’remnants’ (excitation, hadronization)...
QGSJET-II: full resummation ofdetails of string fragmentation (conversion of color field into
Pomeron-Pomeron interaction diagrams
hadrons)
fully dynamicaltreatment
and manyother things
which make model predictions so
but: based on ’soft’ Pomeron coupling
different⇒ no evolution for the saturation scale...

Model implementations of parton shadowing / saturation
not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

EPOS: via parametrized weights for different configurations
energy- & b-dependent treatment
however: weakpredictive
power models
But also technicaldifferences
betweentreatment of hadronic ’remnants’ (excitation, hadronization)...
QGSJET-II: full resummation ofdetails of string fragmentation (conversion of color field into
Pomeron-Pomeron interaction diagrams
hadrons)
fully dynamicaltreatment
and manyother things
which make model predictions so
but: based on ’soft’ Pomeron coupling
different⇒ no evolution for the saturation scale...

Model implementations of parton shadowing / saturation
not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

EPOS: via parametrized weights for different configurations
energy- & b-dependent treatment
however: weakpredictive
power models
But also technicaldifferences
betweentreatment of hadronic ’remnants’ (excitation, hadronization)...
QGSJET-II: full resummation ofdetails of string fragmentation (conversion of color field into
Pomeron-Pomeron interaction diagrams
hadrons)
fully dynamicaltreatment
and manyother things
which make model predictions so
but: based on ’soft’ Pomeron coupling
different⇒ no evolution for the saturation scale...

Model implementations of parton shadowing / saturation
not included in the old QGSJET
high price to pay: ’flat’ (pre-HERA) parton distributions used

SIBYLL: energy-dependent Q20 -cutoff for minijet production
no dynamical treatment, no b-dependence
doesn’t affect soft processes

EPOS: via parametrized weights for different configurations
energy- & b-dependent treatment
however: weakpredictive
power models
But also technicaldifferences
betweentreatment of hadronic ’remnants’ (excitation, hadronization)...
QGSJET-II: full resummation ofdetails of string fragmentation (conversion of color field into
Pomeron-Pomeron interaction diagrams
hadrons)
fully dynamicaltreatment
and manyother things
which make model predictions so
but: based on ’soft’ Pomeron coupling
different⇒ no evolution for the saturation scale...

MC generators & LHC data

ALICE (NSD)

pp → h±, s = 2.36 TeV

dNch/dη|CMS (NSD)

6

η=0

η=0

pp → h±, s = 900 GeV

dNch/dη|dNch/dη|

η=0

LHC data: Nch (s) rises quicker than predicted by most MCs
CMS (NSD)

6

ALICE (NSD)

6UA5 (NSD)444

pp → h±, s = 7.0 TeV
CMS (NSD)PYTHIA 6.422 (Atlas-CSC)
PYTHIA 6.422 (Atlas-CSC)

2

2

PYTHIA 6.422 (Perugia-0)0

η

PYTHIA 6.422 (Perugia-0)

PYTHIA 8.130 (Tune-1)

2

PYTHIA 8.130 (Tune-1)

PHOJET 1.12 (+PYTHIA 6.11)

PHOJET 1.12 (+PYTHIA 6.11)-2

2

PYTHIA 6.422 (Perugia-0)

PYTHIA 8.130 (Tune-1)

0-4

PYTHIA 6.422 (Atlas-CSC)

4

0
-4

-2

0

η

2

PHOJET 1.12 (+PYTHIA 6.11)

4

0
-4

-2

0

η

2

[plots from d’Enterria et al., Astrop. Phys. 35 (2011)]

4

MC generators & LHC data

ALICE (NSD)

pp → h±, s = 2.36 TeV

dNch/dη|CMS (NSD)

6

η=0

η=0

pp → h±, s = 900 GeV

dNch/dη|dNch/dη|η=0Nch (s) - described better by CR interaction models
CMS (NSD)

6

ALICE (NSD)

6UA5 (NSD)

44

pp → h± , s = 7.0 TeV

4

CMS (NSD)SIBYLL 2.1
QGSJET 01
QGSJET II
EPOS 1.99

SIBYLL 2.1

22

QGSJET 01
QGSJET II
EPOS 1.99

0
-4

-2

0

η

2

4

0
-4

-2

0

η

SIBYLL 2.1
QGSJET 01
QGSJET II
EPOS 1.99

2

2

4

0
-4

-2

0

η

2

4

[plots from d’Enterria et al., Astrop. Phys. 35 (2011)]

MC generators & LHC data

ALICE (NSD)

pp → h±, s = 2.36 TeV

dNch/dη|CMS (NSD)

6

η=0

η=0

pp → h±, s = 900 GeV

dNch/dη|dNch/dη|η=0Nch (s) - described better by CR interaction models
CMS (NSD)

6

ALICE (NSD)

6UA5 (NSD)

44

pp → h± , s = 7.0 TeV

4

CMS (NSD)SIBYLL 2.1
QGSJET 01
QGSJET II
EPOS 1.99

SIBYLL 2.1

22

QGSJET 01
QGSJET II
EPOS 1.99

0
-4

-2

0

η

2

4

0
-4

-2

0

η

SIBYLL 2.1
QGSJET 01
QGSJET II
EPOS 1.99

2

2

4

0
-4

-2

0

η

2

4

[plots from d’Enterria et al., Astrop. Phys. 35 (2011)]
most of the models agree with the data within 10%(surprisingly, the oldest models perform best)

MC generators & LHC data

ALICE (NSD)

pp → h±, s = 2.36 TeV

dNch/dη|CMS (NSD)

6

η=0

η=0

pp → h±, s = 900 GeV

dNch/dη|dNch/dη|η=0Nch (s) - described better by CR interaction models
CMS (NSD)

6

ALICE (NSD)

6UA5 (NSD)

44

pp → h± , s = 7.0 TeV

4

CMS (NSD)SIBYLL 2.1
QGSJET 01
QGSJET II
EPOS 1.99

SIBYLL 2.1

22

QGSJET 01
QGSJET II
EPOS 1.99

0
-4

-2

0

η

2

4

0
-4

-2

0

η

SIBYLL 2.1
QGSJET 01
QGSJET II
EPOS 1.99

2

2

4

0
-4

-2

0

η

2

4

[plots from d’Enterria et al., Astrop. Phys. 35 (2011)]
most of the models agree with the data within 10%(surprisingly, the oldest models perform best)
CR MCs: tuned to data over a wide energy range⇒ loose in details, win in predictive powerMC generators & LHC data

ALICE (NSD)

pp → h±, s = 2.36 TeV

dNch/dη|CMS (NSD)

6

η=0

η=0

pp → h±, s = 900 GeV

dNch/dη|dNch/dη|η=0Nch (s) - described better by CR interaction models
CMS (NSD)

6

ALICE (NSD)

6UA5 (NSD)

44

pp → h± , s = 7.0 TeV

4

CMS (NSD)SIBYLL 2.1
QGSJET 01
QGSJET II
EPOS 1.99

SIBYLL 2.1

22

QGSJET 01
QGSJET II
EPOS 1.99

0
-4

-2

0

η

2

4

0
-4

-2

0

η

SIBYLL 2.1
QGSJET 01
QGSJET II
EPOS 1.99

2

2

4

0
-4

-2

0

η

2

4

[plots from d’Enterria et al., Astrop. Phys. 35 (2011)]
most of the models agree with the data within 10%(surprisingly, the oldest models perform best)
CR MCs: tuned to data over a wide energy range⇒ loose in details, win in predictive power
however: none of the models describes all the observables

MC generators & LHC data

ALICE (NSD)

pp → h±, s = 2.36 TeV

dNch/dη|CMS (NSD)

6

η=0

η=0

pp → h±, s = 900 GeV

dNch/dη|dNch/dη|η=0Nch (s) - described better by CR interaction models
CMS (NSD)

6

ALICE (NSD)

6UA5 (NSD)

44

pp → h± , s = 7.0 TeV

4

CMS (NSD)SIBYLL 2.1
QGSJET 01
QGSJET II
EPOS 1.99

SIBYLL 2.1

22

QGSJET 01
QGSJET II
EPOS 1.99

0
-4

-2

0

η

2

4

0
-4

-2

0

η

SIBYLL 2.1
QGSJET 01
QGSJET II
EPOS 1.99

2

2

4

0
-4

-2

0

η

2

4

[plots from d’Enterria et al., Astrop. Phys. 35 (2011)]
however: none of the models describes all the observables

Effect of model retuning to LHC data?
in the following investigated using the QGSJET-II modelQGSJET-II model
based on combined treatment of soft & hard parton processes

soft Pomeron

QCD ladder=+soft Pomeron

soft processes (q2 < Q20 ):’soft Pomeron’
hard processes (q2 > Q20 ):DGLAP formalism
taken together:’semihard Pomeron’QGSJET-II model
based on combined treatment of soft & hard parton processes

soft Pomeron

QCD ladder=+soft Pomeron

soft processes (q2 < Q20 ):’soft Pomeron’
hard processes (q2 > Q20 ):DGLAP formalism
taken together:’semihard Pomeron’QGSJET-II model
based on combined treatment of soft & hard parton processes

soft Pomeron

QCD ladder=+soft Pomeron

soft processes (q2 < Q20 ):’soft Pomeron’
hard processes (q2 > Q20 ):DGLAP formalism
taken together:’semihard Pomeron’QGSJET-II model
based on combined treatment of soft & hard parton processes

soft Pomeron

QCD ladder=+soft Pomeron

soft processes (q2 < Q20 ):’soft Pomeron’
hard processes (q2 > Q20 ):DGLAP formalism
taken together:’semihard Pomeron’QGSJET-II model
based on combined treatment of soft & hard parton processes

soft Pomeron

QCD ladder=+soft Pomeron

soft processes (q2 < Q20 ):’soft Pomeron’
hard processes (q2 > Q20 ):DGLAP formalism
taken together:’semihard Pomeron’

nonlinear processes (parton shadowing / saturation):
Pomeron-Pomeron interactions

QGSJET-II model
based on combined treatment of soft & hard parton processes

soft Pomeron

QCD ladder=+soft Pomeron

soft processes (q2 < Q20 ):’soft Pomeron’
hard processes (q2 > Q20 ):DGLAP formalism
taken together:’semihard Pomeron’

nonlinear processes (parton shadowing / saturation):
Pomeron-Pomeron interactions
NB: in this model saturation may be reached for soft(q2 < Q20 ) partons onlyNew version of QGSJET-II (QGSJET-II-04)

y ,b

y ,b

2 2

3 3

y ,b

1 1

y ,b

y ,b3

y ,b2

y1,b1

3

5

y ,b1

3

(b)

y ,b5

2

y ,b3

2 2

(a)

y4 ,b41(c)

QGSJET-II-03: only
dominant (’net-like’)
Pomeron-Pomeroninteractions

New version of QGSJET-II (QGSJET-II-04)
y ,b

y ,b

2 2

3 3

y ,b

1 1

y ,b

y4 ,b4
y ,b2

y1,b1

y ,b3
3

y ,b3

(a)

(b)
m1

...
y ,b1

1

(c)
...

5

y ,b1

3

2 2

y ,b5

2

m2

QGSJET-II-03: only
dominant (’net-like’)
Pomeron-Pomeroninteractions

QGSJET-II-04: also ’Pomeronloops’ included

1

small at low parton density
y ,b2... n1...

suppressed at high density2

n2

still a finite correction at large b⇒ influence cross sections &particle production

New version of QGSJET-II (QGSJET-II-04)
y ,b

y ,b

2 2

3 3

y ,b

1 1

y ,b

y4 ,b4
y ,b2

y1,b1

y ,b3
3

y ,b3

(a)

(b)
m1

...
y ,b1

1

(c)
...

5

y ,b1

3

2 2

y ,b5

2

m2

QGSJET-II-03: only
dominant (’net-like’)
Pomeron-Pomeroninteractions

QGSJET-II-04: also ’Pomeronloops’ included

1

small at low parton density
y ,b2... n1...

suppressed at high density2

n2

still a finite correction at large b⇒ influence cross sections &particle production

New version of QGSJET-II (QGSJET-II-04)
y ,b

y ,b

2 2

3 3

y ,b

1 1

y ,b

y4 ,b4
y ,b2

y1,b1

y ,b3
3

y ,b3

(a)

(b)
m1

...
y ,b1

1

(c)
...

5

y ,b1

3

2 2

y ,b5

2

m2

QGSJET-II-03: only
dominant (’net-like’)
Pomeron-Pomeroninteractions

QGSJET-II-04: also ’Pomeronloops’ included

1

small at low parton density
y ,b2... n1...

suppressed at high density2

n2

still a finite correction at large b⇒ influence cross sections &particle production

New version of QGSJET-II (QGSJET-II-04)
y ,b

y ,b

2 2

3 3

y ,b

1 1

y ,b

y4 ,b4
y ,b2

y1,b1

y ,b3
3

y ,b3

(a)

(b)
m1

...
y ,b1

1

(c)
...

5

y ,b1

3

2 2

y ,b5

2

m2

QGSJET-II-03: only
dominant (’net-like’)
Pomeron-Pomeroninteractions

QGSJET-II-04: also ’Pomeronloops’ included

1

small at low parton density
y ,b2... n1...

suppressed at high density2

n2

still a finite correction at large b⇒ influence cross sections &particle production

New version of QGSJET-II (QGSJET-II-04)
y ,b

y ,b

2 2

3 3

y ,b

1 1

y ,b

y4 ,b4
y ,b2

y1,b1

y ,b3
3

y ,b3

(a)

(b)
m1

...
y ,b1

1

(c)
...

5

y ,b1

3

2 2

y ,b5

2

m2

QGSJET-II-03: only
dominant (’net-like’)
Pomeron-Pomeroninteractions

QGSJET-II-04: also ’Pomeronloops’ included

1

small at low parton density
y ,b2... n1...

suppressed at high density2

n2

still a finite correction at large b⇒ influence cross sections &particle production

however: small impact on EAS characteristics
if the model is calibrated to the same data set [SO, 2009]

New version of QGSJET-II (QGSJET-II-04)
y ,b

y ,b

2 2

3 3

y ,b

1 1

y ,b

y4 ,b4
y ,b2

y1,b1

y ,b3
3

y ,b3

(a)

(b)
m1

...
y ,b1

1

(c)
...

5

y ,b1

3

2 2

y ,b5

2

m2

QGSJET-II-03: only
dominant (’net-like’)
Pomeron-Pomeroninteractions

QGSJET-II-04: also ’Pomeronloops’ included

1

small at low parton density
y ,b2... n1...

suppressed at high density2

n2

still a finite correction at large b⇒ influence cross sections &particle production

however: small impact on EAS characteristics
if the model is calibrated to the same data set [SO, 2009]
here: impact of calibration to LHC data

Multiplicity adjustment

4.5

dNch / dηdNch / dηNch (s)-rise: too steep in QGSJET-II-03
p + p → charged hadrons (0.9 TeV c.m.)8p + p → charged hadrons (7 TeV c.m.)

4

7

3.5

6

3

2.5

QGSJET-II-03

-2

0

2

5

4
η

QGSJET-II-03

-2

0

2

η

Multiplicity adjustment

4.5

dNch / dηdNch / dηNch (s)-rise: too steep in QGSJET-II-03
p + p → charged hadrons (0.9 TeV c.m.)8p + p → charged hadrons (7 TeV c.m.)

4

7

3.5

6

3

2.5

QGSJET-II-03

-2

0

2

5

4
η

QGSJET-II-03

-2

0

2

not easy to correct:
hadronization parameters – tuned at fixed target energies
general model parameters – tuned to cross sections & SFs

ηMultiplicity adjustment

4.5

dNch / dηdNch / dηNch (s)-rise: too steep in QGSJET-II-03
p + p → charged hadrons (0.9 TeV c.m.)8p + p → charged hadrons (7 TeV c.m.)

4

7

3.5

6

3

2.5

QGSJET-II-03

-2

0

2

5

4
η

QGSJET-II-03

-2

0

2

not easy to correct:
hadronization parameters – tuned at fixed target energies
general model parameters – tuned to cross sections & SFs

ηMultiplicity adjustmentchanging the cutoff Q20 between soft & hard processes(2.5 → 3 GeV2 )parton saturation operates over a larger kinematic space

4.5

dNch / dηdNch / dη⇒ slows down multiplicity risep + p → charged hadrons (0.9 TeV c.m.)8p + p → charged hadrons (7 TeV c.m.)

4

7

3.5

6

3

QGSJET-II-03

5

QGSJET-II-03

QGSJET-II-04
2.5

-2

0

2

QGSJET-II-04
4

η

-2

0

2

η

Multiplicity adjustmentchanging the cutoff Q20 between soft & hard processes(2.5 → 3 GeV2 )parton saturation operates over a larger kinematic space

4.5

dNch / dηdNch / dη⇒ slows down multiplicity risep + p → charged hadrons (0.9 TeV c.m.)8p + p → charged hadrons (7 TeV c.m.)

4

7

3.5

6

3

QGSJET-II-03

5

QGSJET-II-03

QGSJET-II-04
2.5

-2

0

2

QGSJET-II-04
4

η

-2

0

2

η

Multiplicity adjustmentchanging the cutoff Q20 between soft & hard processes(2.5 → 3 GeV2 )parton saturation operates over a larger kinematic space

4.5

dNch / dηdNch / dη⇒ slows down multiplicity risep + p → charged hadrons (0.9 TeV c.m.)8p + p → charged hadrons (7 TeV c.m.)

4

7

3.5

6

3

QGSJET-II-03

5

QGSJET-II-03

QGSJET-II-04
2.5

-2

0

2

QGSJET-II-04
4

η

-2

0

2

η

Multiplicity: cross check with ATLAS datadNch /dη: model-independent results from ATLAS
qualitatively the same trend

5dNch / dηdNch / dηthe level of (dis)agreement varies for different event selections
p + p → charged hadrons (0.9 TeV c.m.)
Nch > 1, pt > 0.1 GeV

4

3p + p → charged hadrons (7 TeV c.m.)
Nch > 1, pt > 0.1 GeV
6
Nch > 5, pt > 0.5 GeV

Nch > 5, pt > 0.5 GeV

2

8

4

Nch > 0, pt > 0.5 GeV
Nch > 0, pt > 0.5 GeV
QGSJET-II-03
QGSJET-II-04

2
1

0

QGSJET-II-03
QGSJET-II-04

-2

-1

0

1

2

0
η

-2

-1

0

1

2

η

Multiplicity: cross check with ATLAS datadNch /dη: model-independent results from ATLAS
qualitatively the same trend

5dNch / dηdNch / dηthe level of (dis)agreement varies for different event selections
p + p → charged hadrons (0.9 TeV c.m.)
Nch > 1, pt > 0.1 GeV

4

3p + p → charged hadrons (7 TeV c.m.)
Nch > 1, pt > 0.1 GeV
6
Nch > 5, pt > 0.5 GeV

Nch > 5, pt > 0.5 GeV

2

8

4

Nch > 0, pt > 0.5 GeV
Nch > 0, pt > 0.5 GeV
QGSJET-II-03
QGSJET-II-04

2
1

0

QGSJET-II-03
QGSJET-II-04

-2

-1

0

1

2

0
η

-2

-1

0

1

2

η

Multiplicity: cross check with ATLAS datadNch /dη: model-independent results from ATLAS:
overall multiplicity corrections at ∼ 10% level
5

dNch / dηdNch / dη⇒ insignificant for air shower predictions
p + p → charged hadrons (0.9 TeV c.m.)
Nch > 1, pt > 0.1 GeV

4

3p + p → charged hadrons (7 TeV c.m.)
Nch > 1, pt > 0.1 GeV
6
Nch > 5, pt > 0.5 GeV

Nch > 5, pt > 0.5 GeV

2

8

4

Nch > 0, pt > 0.5 GeV
Nch > 0, pt > 0.5 GeV
QGSJET-II-04
QGSJETSIBYLL-2.1

210

QGSJET-II-04
QGSJETSIBYLL-2.1
-2

-1

0

1

2

0
η

-2

-1

0

1

2

η

Multiplicity: cross check with ATLAS datadNch /dη: model-independent results from ATLAS:
overall multiplicity corrections at ∼ 10% level
5

dNch / dηdNch / dη⇒ insignificant for air shower predictions
p + p → charged hadrons (0.9 TeV c.m.)
Nch > 1, pt > 0.1 GeV

4

3p + p → charged hadrons (7 TeV c.m.)
Nch > 1, pt > 0.1 GeV
6
Nch > 5, pt > 0.5 GeV

Nch > 5, pt > 0.5 GeV

2

8

4

Nch > 0, pt > 0.5 GeV
Nch > 0, pt > 0.5 GeV
QGSJET-II-04
QGSJETSIBYLL-2.1

210

QGSJET-II-04
QGSJETSIBYLL-2.1
-2

-1

0

1

2

0
η

-2

-1

0

1

2

η

Production of (anti-)baryons

Generally, enhanced production of (anti-)baryons may increase EASmuon content [Pierog & Werner, PRL (2008)]
more energy kept in the hadronic cascade
more cascade steps (no decay for nucleons) ⇒ higher NµProduction of (anti-)baryons

Generally, enhanced production of (anti-)baryons may increase EASmuon content [Pierog & Werner, PRL (2008)]
more energy kept in the hadronic cascade
more cascade steps (no decay for nucleons) ⇒ higher NµProduction of (anti-)baryons
Generally, enhanced production of (anti-)baryons may increase EASmuon content [Pierog & Werner, PRL (2008)]
more energy kept in the hadronic cascade

dn/dydpt (c/GeV)

more cascade steps (no decay for nucleons) ⇒ higher Nµ
10

10

10

10

p+p → pbar (0.9 TeV c.m., ALICE)-1| y| < 0.5-2p̄-production at LHC:
no excess compared tomost model predictions

QGSJET-II-04
QGSJET-II-03
QGSJETSIBYLL-2.1

-3

-4

0

0.5

1

1.5

2
2.5
pt (GeV/c)⇒ no corrections for NµProduction of (anti-)baryons
Generally, enhanced production of (anti-)baryons may increase EASmuon content [Pierog & Werner, PRL (2008)]
more energy kept in the hadronic cascade

dn/dydpt (c/GeV)

more cascade steps (no decay for nucleons) ⇒ higher Nµ
10

10

10

10

p+p → pbar (0.9 TeV c.m., ALICE)-1| y| < 0.5-2p̄-production at LHC:
no excess compared tomost model predictions

QGSJET-II-04
QGSJET-II-03
QGSJETSIBYLL-2.1

-3

-4

0

0.5

1

1.5

2
2.5
pt (GeV/c)⇒ no corrections for NµProduction of strange particles
Enhancement of strange particle production may also increase Nµ
more energy channeled into hadronic cascade

0.4

dn/dy

dn/dy

QGSJET-II-03: noticeable correction required by LHC datap + p → KS , Λ (0.9 TeV c.m., CMS)

0.6
p + p → KS , Λ (7 TeV c.m., CMS)QGSJET-II-03
0.3

QGSJET-II-03

QGSJET-II-04

QGSJET-II-04
0.4

KS

KS
0.2
Λ

Λ

0.2

0.1

0

0

0.5

1

1.5

2
y

0

0

0.5

1

1.5

2
y

Production of strange particles
Enhancement of strange particle production may also increase Nµ
more energy channeled into hadronic cascade

0.4

dn/dy

dn/dy

QGSJET-II-03: noticeable correction required by LHC datap + p → KS , Λ (0.9 TeV c.m., CMS)

0.6
p + p → KS , Λ (7 TeV c.m., CMS)QGSJET-II-03
0.3

QGSJET-II-03

QGSJET-II-04

QGSJET-II-04
0.4

KS

KS
0.2
Λ

Λ

0.2

0.1

0

0

0.5

1

1.5

2
y

0

0

0.5

1

1.5

2
y

Production of strange particles
Enhancement of strange particle production may also increase Nµ
more energy channeled into hadronic cascade
QGSJET-II-03: noticeable correction required by LHC data

0.4

dn/dy

dn/dy

higher kaon yields in older models (QGSJET, SIBYLL)
p + p → KS , Λ (0.9 TeV c.m., CMS)
0.3

p + p → KS , Λ (7 TeV c.m., CMS)

0.6

QGSJET-II-04

QGSJET-II-04

QGSJETQGSJETSIBYLL-2.1

KS

SIBYLL

KS
0.4

0.2
Λ

0

0

0.5

Λ

0.2

0.1

1

1.5

2
y

0

0

0.5

1

1.5

2
y

cross section (mb)

Inelastic cross section

150

σtot

QGSJET-II-04
QGSJET-II-03
SIBYLL-2.1

100
σinel
σel

50

0
10

2

10

3

4

10
c.m. energy (GeV)side-effect of higher
Q20 -cutoff: slower rise ofcross sections
e.g., σtot
pp - consistent with
E710 data at 1.8 TeV

cross section (mb)

Inelastic cross section

150

σtot

QGSJET-II-04
QGSJET-II-03
SIBYLL-2.1

100
σinel
σel

50

0
10

2

10

3

4

10
c.m. energy (GeV)side-effect of higher
Q20 -cutoff: slower rise ofcross sections
e.g., σtot
pp - consistent with
E710 data at 1.8 TeV

cross section (mb)

Inelastic cross section
150

σtot

QGSJET-II-04
QGSJET-II-03
SIBYLL-2.1

100
σinel
σel

50

0
10

2

10

3

4

10
c.m. energy (GeV)QGSJET-II-04

side-effect of higher
Q20 -cutoff: slower rise ofcross sections
e.g., σtot
pp - consistent with
E710 data at 1.8 TeV
lower cross sections now
supported by LHC data

QGSJET-II-03

SIBYLLMBTSAND

54.1

62.3

68.4

MBTSOR

60.8

69.8

74.7

ATLAS

51.9 ± 5.7

58.7 ± 6.5√
Table: Model predictions for “visible” cross sections (in mb) at s = 7
TeV for ATLAS MB triggers: at least one charged hadron at−3.84 < η < −2.09 and/or at 2.09 < η < 3.84 (MBTSAND/OR ).

σinel (mb)Proton-air cross section & Xmax

600

p - air

500
400
SIBYLL-2.1
QGSJET-II-03
QGSJET-II-04

300
200
10

4

10

6

10

8

10

10
E0 (GeV)

reduction of σinelpp⇒ slower energy-rise of
proton-air cross section
deeper shower penetration

σinel (mb)Proton-air cross section & Xmax

600

p - air

500
400
SIBYLL-2.1
QGSJET-II-03
QGSJET-II-04

300
200
10

4

10

6

10

8

10

10
E0 (GeV)

reduction of σinelpp⇒ slower energy-rise of
proton-air cross section
deeper shower penetration

Xmax (g/cm2)

Proton-air cross section & Xmax

850

p-induced EAS

800

elongation rate (ER)reduced above 1 EeV

750

SIBYLL-2.1
QGSJET-II-03
QGSJET-II-04

700
10

18

10

19

E0 (eV)

NB: similarity between
QGSJET-II-04 and SIBYLL- misleading (ER-increase
will be even larger there)

Xmax (g/cm2)

Proton-air cross section & Xmax

850

elongation rate (ER)reduced above 1 EeV

p-induced EAS

NB: similarity between
QGSJET-II-04 and SIBYLL- misleading (ER-increase
will be even larger there)

800
750
QGSJETQGSJET-II-04

700
10

18

10

19

E0 (eV)

however: inelasticityrelated uncertainty remains

Xmax (g/cm2)

Proton-air cross section & Xmax

850

elongation rate (ER)reduced above 1 EeV

p-induced EAS

NB: similarity between
QGSJET-II-04 and SIBYLL- misleading (ER-increase
will be even larger there)

800
750
QGSJETQGSJET-II-04

700
10

18

10

19

E0 (eV)

however: inelasticityrelated uncertainty remains
QGSJET/QGSJET-II-04:
large Xmax differenceImpact on CR composition studies

overall effect of the retuning on air shower predictions:less than 10% change for muon number (Nµ )shower maximum Xmax shifted deeper above 1018 eV(by less than 20 g/cm2 at 1020 eV)

Impact on CR composition studies

overall effect of the retuning on air shower predictions:less than 10% change for muon number (Nµ )shower maximum Xmax shifted deeper above 1018 eV(by less than 20 g/cm2 at 1020 eV)

Impact on CR composition studies

overall effect of the retuning on air shower predictions:less than 10% change for muon number (Nµ )shower maximum Xmax shifted deeper above 1018 eV(by less than 20 g/cm2 at 1020 eV)

Impact on CR composition studies

overall effect of the retuning on air shower predictions:less than 10% change for muon number (Nµ )shower maximum Xmax shifted deeper above 1018 eV(by less than 20 g/cm2 at 1020 eV)

good news: hadronic physics at & around the ’knee’ – robustImpact on CR composition studies

overall effect of the retuning on air shower predictions:less than 10% change for muon number (Nµ )shower maximum Xmax shifted deeper above 1018 eV(by less than 20 g/cm2 at 1020 eV)

good news: hadronic physics at & around the ’knee’ – robust
but: challenge for UHECR studies
Xmax – RMS(Xmax ) contradiction: smaller ’inelasticity’ ?
(to approach heavy composition with hXmax i)
explanation of muon excess – extremely difficult

Impact on CR composition studies

overall effect of the retuning on air shower predictions:less than 10% change for muon number (Nµ )shower maximum Xmax shifted deeper above 1018 eV(by less than 20 g/cm2 at 1020 eV)

good news: hadronic physics at & around the ’knee’ – robust
but: challenge for UHECR studies
Xmax – RMS(Xmax ) contradiction: smaller ’inelasticity’ ?
(to approach heavy composition with hXmax i)
explanation of muon excess – extremely difficult

Impact on CR composition studies

overall effect of the retuning on air shower predictions:less than 10% change for muon number (Nµ )shower maximum Xmax shifted deeper above 1018 eV(by less than 20 g/cm2 at 1020 eV)

good news: hadronic physics at & around the ’knee’ – robust
but: challenge for UHECR studies
Xmax – RMS(Xmax ) contradiction: smaller ’inelasticity’ ?
(to approach heavy composition with hXmax i)
explanation of muon excess – extremely difficult

Summary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

Summary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

Summary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

Summary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

2

decisive tool – measurements of CR composition

Summary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

2

decisive tool – measurements of CR composition
however: results depend strongly on hadronic MC models

Summary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

2

decisive tool – measurements of CR composition
however: results depend strongly on hadronic MC models

3

first lessons from LHC data:
CR interaction models behave reasonably wellonly cosmetic corrections seem to be needed
exception: reduction of σinel
pp required (for most of the models)Summary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

2

decisive tool – measurements of CR composition
however: results depend strongly on hadronic MC models

3

first lessons from LHC data:
CR interaction models behave reasonably wellonly cosmetic corrections seem to be needed
exception: reduction of σinel
pp required (for most of the models)Summary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

2

decisive tool – measurements of CR composition
however: results depend strongly on hadronic MC models

3

first lessons from LHC data:
CR interaction models behave reasonably wellonly cosmetic corrections seem to be needed
exception: reduction of σinel
pp required (for most of the models)Summary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

2

decisive tool – measurements of CR composition
however: results depend strongly on hadronic MC models

3

first lessons from LHC data:
CR interaction models behave reasonably wellonly cosmetic corrections seem to be needed
exception: reduction of σinel
pp required (for most of the models)Summary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

2

decisive tool – measurements of CR composition
however: results depend strongly on hadronic MC models

3

first lessons from LHC data:
CR interaction models behave reasonably wellonly cosmetic corrections seem to be needed
exception: reduction of σinel
pp required (for most of the models)

4

impact on experimental CR studies:Summary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

2

decisive tool – measurements of CR composition
however: results depend strongly on hadronic MC models

3

first lessons from LHC data:
CR interaction models behave reasonably wellonly cosmetic corrections seem to be needed
exception: reduction of σinel
pp required (for most of the models)

4

impact on experimental CR studies:astrophysical origin of the CR ’knee’ – supported by LHC data(no exotic physics observed at mb level)
UHECR compostion puzzle – further aggravated: small room
to explain the ’muon excess’, Xmax / RMS(Xmax ) inconsistencesSummary
1considerable progress in studing ultra-high energy CRs
high energy (GZK?) cutoff firmly confirmed
first hints towards astrophysical sources of UHECR

2

decisive tool – measurements of CR composition
however: results depend strongly on hadronic MC models

3

first lessons from LHC data:
CR interaction models behave reasonably wellonly cosmetic corrections seem to be needed
exception: reduction of σinel
pp required (for most of the models)

4

impact on experimental CR studies:astrophysical origin of the CR ’knee’ – supported by LHC data(no exotic physics observed at mb level)
UHECR compostion puzzle – further aggravated: small room
to explain the ’muon excess’, Xmax / RMS(Xmax ) inconsistences

Prospects

1

expected/desirable theoretical progress:
reliable QCD treatment of ’dense’ parton systems⇒ of Nch (s) ⇒ muon content of air showers
good understanding of ’baryon stopping’ mechanism ⇒ of Xmax

Prospects

1

expected/desirable theoretical progress:
reliable QCD treatment of ’dense’ parton systems⇒ of Nch (s) ⇒ muon content of air showers
good understanding of ’baryon stopping’ mechanism ⇒ of Xmax

Prospects

1

expected/desirable theoretical progress:
reliable QCD treatment of ’dense’ parton systems⇒ of Nch (s) ⇒ muon content of air showers
good understanding of ’baryon stopping’ mechanism ⇒ of Xmax

Prospects

1

expected/desirable theoretical progress:
reliable QCD treatment of ’dense’ parton systems⇒ of Nch (s) ⇒ muon content of air showers
good understanding of ’baryon stopping’ mechanism ⇒ of Xmax

2

expected/desirable input from LHC:
measurements of total & diffractive cross sections by TOTEM⇒ reliable understanding of RMS(Xmax )studies of ’baryon stopping’ by LHCf ⇒ understanding of Xmax

Prospects

1

expected/desirable theoretical progress:
reliable QCD treatment of ’dense’ parton systems⇒ of Nch (s) ⇒ muon content of air showers
good understanding of ’baryon stopping’ mechanism ⇒ of Xmax

2

expected/desirable input from LHC:
measurements of total & diffractive cross sections by TOTEM⇒ reliable understanding of RMS(Xmax )studies of ’baryon stopping’ by LHCf ⇒ understanding of Xmax

Prospects

1

expected/desirable theoretical progress:
reliable QCD treatment of ’dense’ parton systems⇒ of Nch (s) ⇒ muon content of air showers
good understanding of ’baryon stopping’ mechanism ⇒ of Xmax

2

expected/desirable input from LHC:
measurements of total & diffractive cross sections by TOTEM⇒ reliable understanding of RMS(Xmax )studies of ’baryon stopping’ by LHCf ⇒ understanding of Xmax