th: 25 anniversary
What was learned
What's next
Johann Collot
Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P31

招待ありがとう

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3

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Large Hadron Collider (LHC)run 1 (2010-2012) :7 and 8 TeV pp collisions
2 x 30 fb-1 delivered
run II : (2015-2018, in progress)
Ecm = 13 TeV
2 x 150 fb-1 expected

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3

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A Toroidal LHC ApparatuS
weight : 7000 t~5000 members
187 institutions (16 in Japan)
38 countries
21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3

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Together with LHC, the oldest
and longest experimental projectin the high-energy community.
And still like 20 years to come.
Most of the students joining
ATLAS today were not born whenit all started.

Baked by Katherine Leney of ATLAS

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P35

ATLAS in history
1984 : Lausanne workshop
1989 : Barcelona workshop
1993 : Approval
Early project program

2000 : assembly in cavern starts

Pre-series

1992 : ATLAS LoI
official ATLAS birth year
Concerted design

2004 : cavern tests Septembre 2008 :LHC starts operationstartCommissionning

Construction

Johann Collot

Operation

Construction

Data taking + analysis + upgrades> 2030 ...

2012 : Higgs discovery
6July 4th 2012 : day of glory
CERN's main auditorium had never been so small

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3

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What was learned since 2010
Confirmation that hadron colliders are search and discovery machines.
But also that they can deliver precision measurements in particular of thestandard model parameters.
768 publications since 2010
Each bringing new knowledge !
No way to report on even 1/10 ofthese in 30 minutes - Apologies tomy numerous ATLAS colleagues

Exotic Models
Standard Model
Super Symmetry
Higgs
Top physics
Heavy Ions
B physics

https://twiki.cern.ch/twiki/bin/view/AtlasPublic/Publications
21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3

8lStandard Model (SM) : Elementary particles
emuon
electrontau neutrino
neutrino
weak bosons
neutrinop Q=0t isospin = 1/2
o Q= - |e|Photonn isospin = -1/2
taumuonselectronu quarkqu Q = 2/3 |e|a isospin = 1/2
r q= -1/3 |e|k isospin =-1/2
d quarks
Johann Collotc (charm) t (top)
quark
quark

Gluons

Higgs boson
WeakInteractions (strange) b (bottom)
quark
quark

Electromagnetic Interaction
Strong color interaction
9Standard Model (SM)With massless neutrinos, SM is a 19 free-parameter model :9 elementary particle masses : me , mµ , mτ , mu , md , ms , mc , mb , mt
1 vector boson mass : mW
1 weak mixing angle : θW
2 coupling constants : GF , αs1 Higgs mass : mh
4 quark mixing parameters (CKM matrix) : 3 mixing angles + 1 CP violation phase
1 QCD CP violation phase : ΘQCD ≈ 0

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P310Standard Model
Taking into account massive & mixed neutrinos, at least 7 more free parameters are needed :3 more neutrino masses : mν1 , mν2 , mν3
4 lepton mixing parameters (PMNS matrix) : 3 mixing angles + 1 CP violation phase
But in fact more is needed, in particular on hadron colliders :Parton Distribution Functions (PDF) (Empirical fit of short-scale partonic proton structure)
Parametrization of parton showering and hadronisation processes.
Simulation of interaction of particles with matter.
21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P311

Standard Model : is 19 (26+) too many ?
Perhaps, but please tell us which of thoseshould be removed and why !
PARAMETERS
The problem is more that - the W mass taken apart - none of these parametervalues were ever predicted (or any other words all predictions turned out to be wrong ).
Generation of elementary particle mass is far from being explained as there are still as
many coupling constant values as mass values.
mt / me ≈ 3.6 108 (spread even worse if we consider neutrino masses)
Many astrophysical observations not explained : dark matter, dark energy, baryon asymmetry
There's work for many generations ahead !
Quantum gravitation is not included
21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3

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Standard Model (SM)With massless neutrinos, SM is a 19 free-parameter model :9 elementary particle masses : me , mµ , mτ , mu , md , ms , mc , mb , mt
1 vector boson mass : mW
ATLAS & CMS
prime targets in the
2 coupling constants : GF , αsabsence of observation of
1 Higgs mass : mh
new physics phenomena.
4 quark mixing parameters (CKM matrix) : 3 mixing angles + 1 CP violation phase

1 weak mixing angle : θW

1 QCD CP violation phase : ΘQCD ≈ 021 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P313

Higgs boson : mh
High mass resolution channels : h → ZZ* → 4 l ; h → γγ

http://cdsweb.cern.ch/record/2621479
21 September 2018

http://cdsweb.cern.ch/record/2628771

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P314

Higgs boson : mhHiggs boson mass
known at a 2 per mille
precision already !

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3

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Higgs boson : ttH production~ 1% of total Higgs boson production cross sectionpp
σtth (ATLAS measured value) =670±90 (stat) ± 110 (sys) fb(6.3 standard deviation observation)
multilepton means H->WW* , ZZ*, τ+τ- with multiple leptons in product decays
Phys. Lett. B 784 (2018) 173 , arXiv : 1806.0042v2
21 September 2018Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P316

Observation of h -> b b with Wh or Zh production

pbp
inspirehep.net/record/1691634
21 September 2018bVH (bb) observed significance = 4.9 SDH->bb observed significance = 5.3 SD

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3

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Fundamental scalar field physics
Higgs discovery confirms the existence of a new class of fundamental particles.
More Higgses are predicted by almost all Beyond the Standard Model (BSM) theories (stay tuned).
Fundamental scalar fields probably played a crucial role at the beginning of Universe
UniverseIf Universe compared to a piston.
Initially vacuum energy density ρ = cte > 0Universe expansion : dV > 0ρ dV = - p dV > 0V(φ)

Initiallyρ = cteInitial pressure (p) negative => exponential expansion => inflation
21 September 2018

Vacuum energy

φInflaton

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P318

Solution to Universe horizon problemscale a(t)V0 > c ! No causal point at the beginning ! No temperature equilibrium.
tscale a(t)v0 exp α t
v0 < c21 September 2018

inflation : causal start ! Initial temperature equilibrium.
Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3t
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Top mass measurement
PDG 2018 average
mt = 173 ± 0.4 GeV

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P320

Single (electroweak) top production

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P321

W mass (precision) measurement
ATLAS W mass measurement
at 7 TeV (2018)

Template fits of e,µ transverse momentum
and W transverse mass distributions
https://inspirehep.net/record/1510564
21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P322

W mass (precision) measurement
Almost reaching the precisionof Tevatron, but much moredata to analyze.

https://inspirehep.net/record/1510564
21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P323

mw - mtop - mh SM consistency testGrey contour obtained byglobal fit of electroweak
data with as input LHC
Higgs mass measurement.
mw and mtop let free.
Blue bands depict ATLAS separated
top and W mass measurements.
Yellow contour, ATLAS
combined top and W massmeasurement.
https://inspirehep.net/record/1510564
21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P324Measurement of (effective) weak mixing angle
ATLAS ICHEP 2018
Analysis of angular distributionof leptonic (e,µ) Z boson
decays.

http://cdsweb.cern.ch/record/2630340
21 September 2018Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P325

Beyond the Standard Model searches
Several hundred searches were conducted to find new physics phenomena. This is perhaps
the most active analysis field of ATLAS.
●●●SUSY particles
New vector bosons from new gauge symmetries APOLOGIES TO ALL MY
ATLAS COLLEAGUESExtra neutral or charged Higgses
FOR NOT REPORTING●Extra dimension particles●Compositeness●Many other exotic models

ON THIS. PLEASE KEEP
GOING ON, IT WILL PAY
OUT SOME DAY.

Alas ! No convincing sign of new physics showed up for the time being, but the final word
is very far from being said ! Stay tuned ! Even better join us & participate.
21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P326

What's next

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P327

Major discovery rate over last 50 years
1973 : weak neutral currents
1974 : c quark
1977 : b quark and tau lepton
1983 : W and Z
1995 : t quark
1998 : neutrino mixing
2012 : Higgs boson

21 September 2018

1 major discovery every 5 years
on average.
And max. interval = 14 years
Next discovery could be next year or in 2026.

Research in fundamental physics is a school of patience(and hard but interesting work !)Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P328

Run III and high-luminosity LHC

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P329

Phase-I ATLAS upgrade

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3

before Run III
2018-201930

Phase-II ATLAS upgrade
before Run IV
2023-2025

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P331

Run III and HL-LHC prospects
Will be reappraised soon for European Strategy Update

http://cdsweb.cern.ch/record/2038565
http://cdsweb.cern.ch/record/1956710
21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P332

And beyond LHC

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P333

International Linear Collider : ILCIn Japane+e- collider
250-1000 GeV
starts in 2040 ?

Johann Collot

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Future Circular Collider : FCC
FCC-ee : e+e- collider - up to 350 GeV
starts in 2040 ?
FCC-pp : pp collider - up to 100 TeV
starts in 2060 ?

Johann Collot

35Compact Linear International collider : CLIC

e+e- collider
starts in2040 ?

Johann Collot

36Conclusion
LHC has promoted
fundamental scalar fields
to credible physical entities. It
would be strange that nature
has made the Higgs boson aunique child ! No convincing
BSM sign in LHC data till now.
● Future looks bright (for youngstudents) with a clear objective :bridging micro & macro physics.
●21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P337

あなたの注意をありがとう

21 September 2018

Johann Collot, Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P338