Heavy-flavour productions in the relativistic
heavy ion collisions
Shingo Sakai, Univ. of Tsukuba

Heavy Flavour (HF) in pp, p-Pb & Pb-Pb! Heavy-flavour (charm & beauty) production!

Initial hard scatterings (MHF >> ΛQCD)!

Flavour creation, flavour excitation, gluon splitting! pp collisions

Test for perturbative QCD (pQCD)! Reference for heavy ion collisions (both experiment & theory)!

! Heavy ion collisions

Created in initial parton-parton scatterings! Traverse and interact with the hot & dense QCD matter!

A good probe to study properties of the QCD matter! Energy loss (RAA), collectivity (v2), hadronization!

! pA collisions!

Control measurement for heavy ion collisions to disentangle
initial from final state effects!

2

Cold nuclear matter effect on heavy-flavour production

Energy Loss of heavy flavours! In-medium parton energy loss
! Radiative energy loss (PLB 632, 81)! gluon bremsstrahlung! smaller energy loss for heavy than for light quarks
due to “dead cone” effect (PLB 519 (2001) 199.)! energy loss depends on the colour charge and islarger for gluons than for quarks! Collisional energy loss (PLB 649, 139)
! energy loss via elastic scattering! Theoretical predictions:! mass & colour charge dependence of energy loss
! Eloss(g) > Eloss(u,d,s) > Eloss(c) > Eloss(b)Nuclear modification factor

π
AA

R
3

D
AA

<R

B
AA

<R

?

d N AA dpTRAA ( pT ) =TAA × dσpp dpT

Azimuthal anisotropy of Heavy flavoursｙ" Elliptic flowdN/d(φ-ψRP) = …+ N0(1+2v2cos(2(φ-ψRP))) +…

ｘ! Transfer initial spatial anisotropy

to momentum anisotropy
Initial spatial anisotropy# macroscopic: hydro model=> pressure gradient# microscopicpｙ=> scattering in the medium! Low pT
! coupling of heavy quarks withthe medium and their thermalizationp! Intermediate pT!Hadronization mechanism (recombination)ｘ! High pT
Momentum space anisotropy! Path-length dependence of energy loss
4of particle emission

! Heavy-flavour results in pp collisions

5

HF production in pp collisions at RHIC

! Charm and beauty production via electrons are in good agreement withFONLL calculation
6

HF production in pp collisions at LHC
Phys. Rev. D 86, 112007

c->e + b->e (eHF)

Phys. Lett. B 708(2012) 265

c->µ + b->µ (µHF)! Productions of leptons (e,µ) from charm+ beauty decays in different rapidity ranges
are well described by pQCD calculations
7

Charm production in pp collisions at LHC
CMS-HIN-16-005

JHEP1603(2016)159

pp, s=7 TeV
102
Prompt D0, |y|<0.5
ALICE

T

d2σ/(dp dy ) (µb GeV-1 c )JHEP 1201 (2012) 128

10

FONLL

5 TeV
1

7 TeV
10−1
0

13 TeV± 3.5% lumi, ± 1.3% BR uncertainty not shown

2

4

6

8

10

12

14

16

p (GeV/c )ALI−PUB−111909

T! D meson production mid- and forward-rapidity is in good agreementwith pQCD calculations! upper side of the FONLL uncertainty band
! various energies: 5.02, 7 and 13 TeV! from pT = 0 to 100 GeV/c8

Beauty production in pp collisions at LHC
CMS-DP-2016-016! B meson production is in good agreementwith pQCD calculations

9Beauty jets production in pp collisions at LHC (2)JHEP 04 (2012) 084! b-jet productions in pp collisions at 7 TeV! production is well described with MC@NLO in large rapidity regions
10

Total c-cbar & b-bbar cross section in pp
arXiv:1506.03981

Phys. Lett. B 738! Cross section of charm and beauty are in good agreement with pQCD
! Beam energy dependence is consistent with pQCD (NLO, FONLL)
11

! Heavy-flavour results in pA collisions

12

p-A collisions! Heavy-flavour in p-A collisions!

control measurement for heavy-ion collisions todisentangle initial (cold nuclear matter effects) from final
state effects! Cold nuclear matter effects!

nuclear modification of Parton
distribution Functions (PDF):
shadowing or gluon saturation
K.J. Eskola et al., JHEP 0904(2009)65
H. Fuji & K. Watanabe, NPA 915 (2013) 1

energy loss I. Vitev et al., PRC 75(2007) 064906! kT broadening (Cronin enhancement)! multiple collisions!

A.M. Glenn et al., PLB 644(2007)11913€

d N pPb dpT
R pPb ( pT ) =TAA × dσpp dpT

RdA of eHF & µHF at RHIC

PRL 109, 242301! HF production in d+Au at 200 GeV! mid-, forward & backward
14

RpPb of D, B and eHF at mid-rapidity at LHC
R pPb

PRL 113 (2014) 232301

PRL 115 (2016) 032301

Phys. Lett. B 754 (2016) 81-93
2.5

ALICE

1.6
1.4

0

+

*+

Average D , D , D-0.96<y cms<0.04

2

1.2

eHF

R pPb

0.8

1

0.6

0.2

ALICE

1.5

1

0.4

p−Pb, s NN = 5.02 TeV
c,b → (e+ + e-)/2, −1.065 < y cms < 0.135

p-Pb, s NN=5.02 TeV

D mesonKang et al.: incoherent multiple scattering
Sharma et al.: coherent scattering + CNM
FONLL + EPS09NLO shad.
Blast wave calculation
Normalisation uncertainty

0.5

CGC (Fujii-Watanabe)
pQCD NLO (MNR) with CTEQ6M+EPS09 PDF
Vitev: power corr. + k broad + CNM Eloss
T

0
0

5

10

15

20

25

p (GeV/c )T

ALI−PUB−79415

0

2

4

6

8

10

p (GeV/c )ALI−PUB−100497

T! RpPb of D mesons, B mesons and eHF is consistent with unity! No significant cold nuclear matter effects on heavy-flavour production! Theoretical calculations with CNM effects are consistent with data
! predict a small suppression at low pT due to gluon saturation at low x

15

12RpA: RHIC vs. LHC
2.5
p−Pb, s NN = 5.02 TeV
c,b → (e+ + e-)/2, −1.065 < y cms < 0.135

ALICE

2

R pPb

1.5

1
Kang et al.: incoherent multiple scattering
Sharma et al.: coherent scattering + CNM
FONLL + EPS09NLO shad.
Blast wave calculation
Normalisation uncertainty

0.5

0

2

4

6

8

10

12

p (GeV/c )ALI−PUB−100497

T! Enhancement of eHF production in 0-20% in d+Au is well reproduced by
Blast-wave model [PLB 731 (2014) 51]! Possible enhancement due to radial flow is predicted smaller at LHC! consistent with data
! due to harder D and B meson pT at higher collision energy
16

RpPb of c-jets and b-jets at mid-rapidity
CMS-HIN-15-012

PLB 754 (2016) 59

c-jet
b-jet

! Measured c-jet cross section in p-Pb is consistent with PYTHIA simulation! RpPb of b-jet with PYTHIA-based estimation is consistent with unity! considering the uncertainty on the PYTHIA reference17

D production at forward-backward rapidity
2
LHCb
CTEQ6M+EPS09NLO

2

LHCb preliminarysNN=5 TeV
Backward

1.5

RFB

1.5

2.5

LHCb preliminarysNN=5 TeV
Forward

RpPb

RpPb

LHCB-CONF-2016-003

LHCb
CTEQ6M+EPS09NLO

LHCb preliminary
pPb sNN=5 TeV

2.5 < |y*| < 4

1

1.5

1
1

0.5

0.5

0.5

0
0

2

4

6

8

pT [GeV/c]

0
0

2

4

6

8

pT [GeV/c]

00stat. uncert.
total uncert.
CTEQ6M+EPS09NLO

2

4

6

! D0 production at forward and backward rapidity! forward: p-going, 1.5 < y < -4
! backward: Pb-going, -5 < y < -2.5
! Significant D0 production asymmetry in forward – backward rapidity regions! Measurements are consistent with a theoretical calculation! NLO with CTEQM and EPS09NLO
18

8pT [GeV/c]

B->J/Ψ production at forward-backward rapidity
JHEP 02 (2014) 072! B->J/Ψ production at 1.5 < η < 4.0 (forward) and -5 < η < -2.5 (backward)! RFB of B->J/Ψ is asymmetry! backward yield is suppressed w.r.t. forward yield! RFB of B->J/Ψ is larger than RFB of prompt J/Ψ
! indicate cold nuclear matter effect is less pronounced for b hadrons19

! Heavy-flavour results in AA collisions

20

D mesons in Au-Au (200 GeV)

! D meson production at 200 GeV in Au-Au collisions! Total production follow binary scale! low pT (< 2 GeV/c): tend larger than unity! recombination, radial flow ?
! high pT (>2 GeV/c): strongly suppressed! indicate charm energy loss in the matter
21

RAA of eHF (c->e and b->e) in Au-Au (200 GeV)! RAA of D->e and B->e
! Strong suppression both electrons
original from charm and beauty
indicate charm and beauty energy
loss in the matter! RAA of B->e and D->e are consistent
within current uncertainty! not conclude mass dependence
of energy loss22

D mesons in central Pb-Pb collisions (2.76 TeV)JHEP 03 (2016) 081, JHEP 03 (2016) 082

CMS-HIN-16-001! Strong suppression of D mesons production! similar magnitude of suppression in 2.76 and 5.02 TeV! suppression observed up to 100 GeV/c at 5.02 TeV! DS tends to larger : a hint of recombination process! Suggest significant energy loss of charm in the medium
23

eHF & µHF production in Pb-Pb collisions (2.76 TeV)
40-50% (eHF), 40-80%(µHF)

2
Pb-Pb, sNN = 2.76 TeV
Centrality class 0-10%

1.8

RAA

R AA

0-10%
ALICE Preliminary

1.8

1.6
1.4
1.2

2

e±←HF*, -0.6<y<0.6

1.6µ±←HF, 2.5<y<4

1.4

Syst. uncertainty

1

1.2

0.8

1

0.6

0.8

0.4

0.6

0.2
0

2

4

6

8

10

12

14

16

18

20

p (GeV/ c )ALI−PREL−101085

T

Heavy flavour decay µ± 40-80% central, 2.5<y<4.0
Heavy flavour decay e± 40-50% central, |y|<0.6
with pp ref. scaled cross section at s = 7 TeVwith pp ref. FONLL calculation at s = 2.76 TeV

0.4±(*) e ←W contribution not subtracted

0

Pb-Pb, sNN = 2.76 TeV

0.2
0
0

HFM: Phys. Rev. Lett. 109 (2012)
2

4

6

8

10

12

14

T

! Strong suppression of eHF (|y|<0.6) & µHF (2.5<y<4) in central collisions! similar suppression of eHF & µHF in different rapidity regions! less suppression in mid-central collisions in both rapidity regions! high pT: large contribution from beauty! Suggest significant energy loss of charm and beauty in the medium
ALI−DER−53851

24

16

18

p (GeV/c)

RHIC vs. LHC: D meson production! Similar order of suppression of
D meson production in 0.2 TeV (Au-Au)
and 2.76 TeV (Pb-Pb) in most-central
collisions at 2<pT<6 GeV/c! Looks there is difference at low pT! recombination, radial flow @ RHIC ?
! shadowing @ LHC ?

STAR, PRL113(2014)142301
ALICE, JHEP1603(2016)081
25

RHIC vs. LHC: HF->e production! Similar order of suppression ofc->e + b->e production in 0.2 TeV(Au-Au) and 2.76 TeV (Pb-Pb)
in most-central collisionsat 3<pT<9 GeV/c! Not imply similar HF energy loss
between RHIC and LHC! combined effect of a denser
medium and harder initial pT
spectrum at LHC
arXiv:1509.06888

26

RAA of B meson decays (B->e & B->J/Ψ) in LHCRAAJHEP 1205 (2012) 063
2.5

Pb-Pb, s NN = 2.76 TeV, 0-20% centrality2b (A c) A e, |y| < 0.8
syst. uncertainty
nomalization uncertainty

1.5

1

0.5

ALICE Preliminary
0

1

2

3

4

5

6

7

8

p (GeV/c )ALI−PREL−74678

T! Suppression of B->e and B->J/Ψ at high pT! lower pT : tends to follow binary scaling (consistent with unity)! high pT (> 3 GeV/c): RAA ~ 0.4-0.5! Suggestions of beauty energy loss in the dense QCD matter
27

RAA of charged particles, D and B->J/Ψ in LHC
CMS-PAS-HIN-16-001
R AA

JHEP 1511 (2015) 205, CMS-PAS-HN-12-014
1.4

Pb-Pb, sNN = 2.76 TeV
π± (ALICE) 8<p <16 GeV/ c , |y |<0.8
T
D mesons (ALICE) 8<p <16 GeV/ c , |y |<0.5
T
Non-prompt J/ ψ (CMS Preliminary)
6.5<p <30 GeV/ c , |y |<1.2 CMS-PAS-HIN-12-014

1.2

T

1

(empty) filled boxes: (un)correlated syst. uncert.
(*) 50-100% for non-prompt J/ ψ

0.8
0.6
0.4

50-80%*

40-50%
30-40%

0.2

20-30%±π shifted by +10 in 〈N part〉00
ALI−DER−93725

50

100

150

200

10-20%

250

300

0-10%

350

400

〈N part〉! The magnitude of D meson suppression is similar to charged particles (π)
within uncertainties at pT > 8 GeV/c! can’t conclude on the expectation : RAA (D) > RAA (π)! RAA of D meson is smaller than RAA of B->J/Ψ
! indication of smaller energy loss of beauty than charm28

Beauty jet in LHC
PRL 113 (2014) 132301! Heavy-flavour jets: allow to address energy loss at parton level! Observed strong suppression of b-jets in most-central collisions! similar magnitude of suppression to inclusive jet! high pT b-jets: largely comes from gluon splitting
29Imbalance of pairs of b jets in LHC

CMS-HIN-16-005! Sub-leading recoil jets
! larger path-length, primary b-jets from flavour creation! Toward increasing imbalance with increasing centrality! similar imbalance as inclusive dijet
30b-bAzimuthal anisotropy of HF (D and e) at RHIC
arXiv: 1405.6348! Non-zero HF v2 (D & eHF) in Au-Au collisions at 200 GeV! v2 at lower energies (62.4 & 39 GeV) is consistent with zero at pT < 2 GeV/c! non-zero light-flavour (π,k & p) v2 in the energy regions (arXiv:1601.07052)
31

Azimuthal anisotropy of D mesons in LHC
v2

PRC 90 (2014) 034904
0.6

Pb-Pb,

0

Prompt D |y |<0.8, v 2{EP}

0.6

ALICE

0.6

Syst. from datasNN = 2.76 TeV

Syst. from B feed-down

0.4

0.4

0.2

0.2

0.2

0

0

0

-0.2

-0.2

-0.2

4

6

8

0.4

Centrality 10-30%

Centrality 0-10%
2Charged particles, v 2{EP,|∆ η|>2}

10 12 14 16 18

p (GeV/c )
T

2

4

6

8

Centrality 30-50%

10 12 14 16 18

p (GeV/c )
T

2

4

6

8

10 12 14 16 18

p (GeV/c )T

ALI−PUB−70100! Non zero D v2 at low pT! Tends to get large from central (0-10%) to mid-central (30-50%)! Hydrodinamical behavior! Consistent with charged particle v2! Charm quarks participate to the collective motion of the system
32

Azimuthal anisotropy of eHF and µHF in LHC
v2

eHF : arXiv: 1606.00321, µHF: PLB 753 (2016) 41-56
0.5

0-10% Pb-Pb, s NN = 2.76 TeV

0.5
0.4

0.4

10-20% Pb-Pb, sNN = 2.76 TeV
e± ← HF, v 2{EP, |∆η| > 0.9}, |y | < 0.7

0.5
0.4

0.3

µ± ← HF, v 2{2, |∆η| > 1.7}, 2.5 < y < 40.3

0.2

0.2

0.2

0.1

0.1

0.1

0

0

0

−0.1

0.1

0.1

0.3

−0.2

ALICE

0

2

4

ALI−PUB−106769

6

8

0.2
10 12
0
p (GeV/ c )
T

2

4

6

8

0.2
10 12
0
p (GeV/c )20-40% Pb-Pb, s NN = 2.76 TeV

2

4

6

8

T

! Non-zero v2 of eHF at |y|<0.7 and µHF at 2.5<y<4! the magnitude is compatible in mid- and forward-rapidities! v2 of eHF measured from pT > 0.5 GeV/c! similar pT dependence to other light hadron v2! v2 at high pT eHF and µHF reflects beauty! Charm quarks participate to the collective motion of the system
33

10 12
p T (GeV/c )Comparison with models (1)+*+ALICE D , D , D average, |y|<0.5

1

Pb-Pb, sNN = 2.76 TeV
Centrality 0-20%

0.8

WHDG rad+coll
POWLANG
Cao, Qin, Bass
Aichelin et al, Coll+LPM radBAMPSTAMU elastic
UrQMD

0.6
0.4
0.2
0
0

2

4

6

8

10

12

14 16
p (GeV/c)T

ALI−DER−48662

2

1.8
1.6

µ ←HF

0

ALICE Preliminary
Pb-Pb, sNN = 2.76 TeV, 0-10% central

R AA

1.2

Heavy flavour decay electron RAA

RAA

JHEP09(2012)112

1.2

1.4
1.2

1

1

0.8

0.8

0.6

0.6

0.4

0.4

0.2

0.2

0
0

2

4

6

8

T

ALI−PREL−77686

0

10 12 14 16 18
p (GeV/c)

0

2

4

6

8

10

ALICE Preliminary

12

14

16

18

20

p (GeV/c )ALI−PREL−101250! Theoretical calculations! initial: with/without cold nuclear matter from PDF! medium modeling: Hydro, Glauber, parton transportation! interaction: radiative, collisional, resonant interaction! hadronization: fragmentation, coalesence! Models represent RAA of D mesons, eHF and µHF! mid- and forward-rapidity regions! high pT leptons (e,µ) mainly from beauty decay
34

Pb-Pb, sNN = 2.76 TeV
2.5 < y < 4Centrality class 0-10%µ±←HF
MC@sHQ+EPOSBAMPS elastic
TAMU elastic
Syst. uncertainty

1.8
1.6

with pp ref. from scaled cross section at s = 7 TeVwith pp ref. from FONLL calculation at s = 2.76 TeVBAMPS el.
BAMPS el. + rad.
TAMU
POWLANG
MC@sHG+EPOS,Coll+Rad(LPM)

1.4

2

T

BAMPS: J. Phys. G 38 (2011) 124152,
POWLANG: Eur. Phys. J C
71(2011)1666,
UrQMD: arXiv:1211.6912,J. Phys. Conf.
Ser. 426,012032(2013),
TAMU: Phys. Rev. C 86 (2012) 014903,
WHDG: J. Phys. G38(2011)124114,
Aichelin: Phys. Rev. C79(2009)044906,
J. Phys. G37(2010)094019
Cao,Qin, Bass: arXiv:1308.0617

Comparison with models (2)RAA

JHEP09(2012)112

arXiv: 1603.00529

1.2
0

+

*+

ALICE D , D , D average, |y|<0.5

1

Pb-Pb, sNN = 2.76 TeV
Centrality 0-20%

0.8

WHDG rad+coll
POWLANG
Cao, Qin, Bass
Aichelin et al, Coll+LPM radBAMPSTAMU elastic
UrQMD

0.6
0.4
0.2
0
0
ALI−DER−48662

2

4

6

8

10

12

14 16
p (GeV/c)T! Model calculations are reasonably reproduced D meson RAA in both RHIC (0.2 TeV
Au-Au) and LHC (2.76 TeV Pb-Pb)

35

Comparison with models (3)0+1

Pb-Pb, sNN = 2.76 TeV
Centrality 0-20%

0.8

WHDG rad+coll
POWLANG
Cao, Qin, Bass
Aichelin et al, Coll+LPM radBAMPSTAMU elastic
UrQMD

0.6
0.4

0.4

4

6

8

10

12

14
16
p (GeV/c)T*+

Pb-Pb, sNN = 2.76 TeV
Centrality 30-50%

0.2
0.1

-0.1
2

+

ALICE D ,D , D average
Syst. from data
Syst. from B feed-down

0.3

0

0.2

ALI−DER−48662

0*+

ALICE D , D , D average, |y|<0.5

00

PRC 90 (2014) 034904
v2

RAA

JHEP09(2012)112
1.2

0
ALI−DER−48710

WHDG rad+coll
POWLANG
Cao, Qin, Bass
Aichelin et al, Coll+LPM rad
BAMPS

2

4

6

8

TAMU elastic
UrQMD

10

12

14
16
p (GeV/c)T! Theoretical calculations! initial: with/without cold nuclear matter from PDF! medium modeling: Hydro, Glauber, parton transportation! interaction: radiative, collisional, resonant interaction! hadronization: fragmentation, coalesence! Large suppression and non-zero v2 (at low pT) are represented by models,
but simultaneous reproduction of the RAA and v2 is challenging
36

Comparison with models (3)! Experimental result! RAA(D) < RAA(B->J/Ψ)! Theoretical model! radiative + collisional energy loss
! used two masses (charm andbeauty) for calculating B->J/Ψ RAA
to study mass dependence! result using beauty mass well
represents centrality dependenceof RAA (B->J/Ψ)! the difference between D meson
and B->J/Ψ is mainly from massin this model

37

Summary! Heavy-flavour productions in pp collisions at 200

GeV, 2.76 TeV, 7 TeV and 13 TeV!

The productions are well described by pQCD calculations! Heavy-ion collisions (Au-Au 200 GeV, Pb-Pb 2.76 &5.02 TeV)!

Strong suppression of heavy-flavour yield! Clear indication for substantial energy loss of charm and beautyin the hot and dense matter!

Non-zero & centrality dependence of v2! Suggest strong re-interaction in the medium! Heavy flavours observed to be significantly affectedby hot and dense QCD medium
38