Sergey Petrushanko(for CMS Collaboration)
SINP MSU Russia

Heavy-ion Physics
at CMS
20th Lomonosov Conference
on Elementary Particle Physics
Moscow, Russia
19-22 August 2021

CMS is a nice heavy-ion experiment
Silicon Tracker|η| < 2.4
ElectromagneticCalorimeter|η| < 3.0
Hadron Calorimeterbarrel and endcap|η| < 3.0
with HF-calorimeter up to|η| < 5.2
Muon Chambers|η| < 2.4

Magnetic field: 3.8 Tesla
Lomonosov 2021

+ CASTOR detector
5.2 < |η| < 6.6+ Zero-degree calorimeter+ TOTEM

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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November 7, 2010 0:27. CMS Control Room.

Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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CMS heavy-ion physics results

110 published/submitted
Heavy-ion Physics CMS papers:
http://cms-results.web.cern.ch/cms-results/public-results/publications/HIN/index.html…and also
Heavy-ion Physics CMS preliminary results:
http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/HIN/index.html

Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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CMS heavy-ion results●●●

Global picture of heavy-ion collisions–multiplicity,–energy,–flow, ...

Hard probes

Pb+Pb collisions

2010-11: 2.76 TeV 0.16/nb
2015-18: 5.02 TeV 1.7/nb–jets–dimuons–

charged hadrons RAA, ...

p+p, p+Pb, Xe+Xe–correlations

–

flow,

–

jets, ...

Lomonosov 2021

p+p 2.76, 5.02, 7, 8, 13 TeV
p+Pb 5.02, 8.16 TeV
Xe+Xe 5.44 TeV
Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

5Charged particle multiplicity
Transverse energy density

JHEP 01 (2018) 045

Lomonosov 2021

PRC 100 (2019) 024902• √s dependence:- p+p, p+Pb, Pb+Pb follow power law

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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FlowReaction
planebeam(contains theimpact parameter)

participants

definesNon-central Pb+Pb “screenshots” from CMS Event Monitor:
Electromagnetic,
Electromagnetic Hadronic Energy and charged particles tracks

Collective motion is observed in the event azimuthal distributions
Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

7Correlations: “RIDGE” everywhere...
Long-range (2 < |Δη| < 4), near-side (Δϕ ≈ 0)
angular correlations were observed in high multiplicity p+p and p+Pbcollisions (as well as in Pb+Pb)

p+p 7 TeVJHEP 09 (2010) 091

Lomonosov 2021

p+Pb 5.02 TeV

PLB 718 (2013) 795

Pb+Pb 2.76 A TeV, 0-5%

JHEP 07 (2011) 076

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

8γp interactions within ultra-peripheral
p+Pb collisions

CMS-PAS-HIN-18-008

The single particle flow coefficient v2(pT) is largerfor γp-enhanced events than for minimum-bias collisions.
Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

9Charm and beauty long-range correlations
in p+Pb collisions
TheoryOpen charm
Hidden charm
Open beauty

PLB 813 (2021) 136036

Lomonosov 2021

No significant flow for nonprompt D0
Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

10Measurement of v2 of Υ in Pb+Pb collisions

In contrast to the J/ψ mesons,no azimuthal anisotropy is observed for the Υ mesons.

PLB 813 (2021) 136036

Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

11Mixed higher-order anisotropic flowin Pb+Pb
EPJ C 80 (2020) 534

The mixed higher-order flow harmonics, v4{Ψ22}, v5{Ψ23}, v6{Ψ222}, v6{Ψ33}, andv7{Ψ223} all have a qualitatively similar pT dependence. Viscous hydrodynamic
calculation with Glauber initial conditions and shear viscosity doesn't provide asimultaneous description.
Lomonosov 2021
Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics
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Xe+Xe as a “bridge” between p and Pb

Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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v2 Xe+Xe vs. Pb+Pb
PRC 100 (2019) 044902

The magnitude of the v2 coefficients for Xe+Xe collisions are larger thanthose found in Pb+Pb collisions for the most central collisions. This is
attributed to a larger fluctuation component in the lighter colliding system.
Lomonosov 2021
Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics
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v2, 3, 4 Xe+Xe vs. Pb+Pb
PRC 100 (2019) 044902

Hydrodynamic models that consider the Xe nuclear deformation
are able to better describe the v2[XeXe]/v2[PbPb] ratio in central collisions
than those assuming a spherical Xe shape.
Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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Hard Probes for Quark-Gluon Plasma

Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

16Hard Probes for Quark-Gluon Plasma

Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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Upsilon suppression in Pb+Pb

PLB 790 (2019) 270

Observation of sequential suppression of Y family.
● No any sign of Υ(3S) in the high statistics 2015 data.
●Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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Upsilon suppression in p+Pb
CMS-PAS-HIN-18-005

All Υ states are found to be suppressed in p+Pb collisions
compared to p+p collisions.
Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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Upsilon suppression in p+Pb and Pb+Pb
CMS-PAS-HIN-18-005

Ordered in binding energy
RpPb Υ(1S) > RpPb Υ(2S) > RpPb Υ(3S)

Largest suppression in Pb+Pb
RpPb > RPbPb

Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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First evidence of X(3872) in Pb+Pb
arXiv:2102.13048

Comparison to ψ(2S)

Result provides a unique experimental input tothe theory, towards elucidating the production
mechanism and the nature of the X(3872).
Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

21Measurement of B0s and B+ mesonin Pb+Pb collisions
CMS-PAS-HIN-19-011

The B0s meson is observed with a statistical significance in excess of
5 standard deviations for the first time in nucleus-nucleus collisions
Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

22Measurement of B0s and B+ mesonin Pb+Pb collisions
CMS-PAS-HIN-19-011●No significant pT-dependence of B0s/ B+ ratio● Model predictions in reasonably wellagreement with data
Lomonosov 2021

●B0s/ B+ ratio in Pb+Pb
compatible withmeasurements in pp

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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The first search for top
using Pb+Pb collisions
PRL 125 (2020) 222001

Using either charged leptons only or charged leptons + b jets.
The measured cross sections are compatible with expectations fromscaled proton-proton data and QCD predictions.
Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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The first search for top
using Pb+Pb collisions
PRL 125 (2020) 222001

4.0 σ significanceConsistent with pQCD

• Top quarks can probe both theinitial and final state• Probing the QGP formation?
Both dilepton multivariate& b-jet counting analyses
The observed significance of the
top signal against thebackground-only hypothesis
amounts to 3.8 and 4.0 standard
deviations in the two methods.
Boosted decision tree
Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

25Jet quenching in Pb+Pb
PRC 84 (2011) 024906
PLB 712 (2012) 176

Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

26Jet radius scan
JHEP 05 (2021) 284

Sensitive to balance
between increasingradiative sources andrecovering re-distributedenergy●

Enables simultaneouscomparisons of model
calculations across jetradii●

CMS observes no radiusdependence to jet energy
loss in central Pb+Pb for
500 GeV < pT jet <1 TeV●

Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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CMS Summary for Heavy-Ions●●Many interesting heavy-ion physics results with the CMS
detector in p+p, p+Pb, Pb+Pb and Xe+Xe...
Future heavy-ion program at the LHC (Run 3 and 4) withthe upgraded CMS detector will provide more exciting
opportunities! Stay tunned!

Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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Two years ago... LOMONOSOV 2019

THANK YOU! СПАСИБО!
SEE YOU! УВИДИМСЯ!
Lomonosov 2021

Sergey Petrushanko (CMS Collaboration) Heavy-Ions Physics

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