Overview of recent ALICE results and Chinese efforts in ALICE · 6/3/2019 · Overview of recent...

Overview of recent ALICE results and Chinese efforts in ALICE

Daicui Zhou (for the ALICE Collaboration)(Central China Normal University, Wuhan, China)

1

Talk at TDLI & INPAC Joint Theoretical Particle Physics Seminar SeriesJune 3, 2019, SJTU, Shanghai

Nucleus (QGP)

Extremely high temperatureand high density

Quark deconfinement

Quark confinement

QGP in early university

New state of material - QGP

2

Heavy-ion collisions at the LHC

Lattice QCD calculation

Phys. Rev. D90 (2014) 094503

• QGP behaves as perfect fluid

• Well described by ideal hydrodynamics

• Low shear viscosity/entropy density (η/s)

• Phase transition calculated by Lattice QCD

• Tc ≈ 155 MeV, εc ≈ 0.5 GeV/fm3

• Heavy-ion collisions at the LHC

• Extremely High temperature: O(1012 K)

• Vanishing baryon chemical potential

• The existence of QGP and its properties

are key issues in QCD for understanding of

confinement and chiral restoration

Daicui Zhou, ALICE Overview and Chinese Efforts in ALICE, June 3, 2019, SJTU, Shanghai 3

Evolution of heavy-ion collisions

• Initial state and pre-equilibrium

• CGC, GLASMA

• Hard parton scattering

• Jet and heavy flavour production

• Creation of Quark-Gluon Plasma

• Thermalization of strongly-interacting matter

• QGP expansion and cooling

• 3D+1 relativistic viscous hydrodynamics

• Phase transition (Tc): partons → hadrons

• Lattice QCD, cross over

• Hadronic phase

• Chemical freeze-out (Tch), rescattering, kinetic freeze-out (Tfo)


Anisotropy: Soft probe of QGP

• Quantify anisotropy: Fourier decomposition of particle azimuthal distribution

relative to the reaction plane (ΨRP) — coefficients v2, v3, v4… vn

• Elliptic flow (v2): spatial anisotropy to momentum anisotropy — large

pressure gradients and more particles emitted in plane — hydrodynamics

• Higher order flow: bring additional constraints on the initial conditions, η/s,

EoS, freeze-out conditions…


Jet: hard probe of QGP

• Jet: a spray of particles from hard parton fragmentation — get closer

access to parton energy

• Out-of-cone radiation: energy loss in jet cone — RAA < 1

➡Jet yield suppression, dijet or hadron–jet acoplanarity…

• In-cone radiation: medium modified fragmentation — RAA = 1

➡Jet shape broadening, modification of transverse energy profile…

• Hard partons produced before the QCD

medium forms

• Interact with the hot and dense medium

QCD medium

QCD vacuum


Heavy flavour: QGP medium tomography7

• Heavy quarks (mc ~ 1.5 GeV, mb ~ 5 GeV): early production (f ~ 1/2mc/b ~

0.1 fm/c << QGP ~ 5-10 fm/c) and hard fragmentation (z→1) ，Experience

full collision history：transport properties

• In-medium energy loss: radiative vs. collisional

• Radiative energy loss —> colour charge, quark mass,

medium density dependence of parton–medium coupling

➡ΔEgluon >ΔElight > ΔEcharm >ΔEbeauty;

➡RAA(B) > RAA(D) > RAA(LH) (?);

• Azimuthal anisotropic (second order flow coefficient v2)

• Low pT: degree of thermalization of heavy quarks in QCD medium

• High pT: path length dependence of heavy quark in-medium energy loss

• Quarkonia suppression and regeneration

• Resonance suppression via color screening — sensitive probe of

deconfined medium

• Regeneration via recombination of heavy quarks, mostly for charmPhys.Lett.B178 (1986) 416 ;Phys. Lett. B 490 (2000) 196; Phys. Rev. C (2001) 054905

TOF

MUON-Arm

V0, T0

EMCAL

TPC

ITS

Central Barrel (|η|<0.9)

• ITS, TPC, TOF: vertexing, 2π tracking and PID

• EMCal/Dcal, PHOS: high-pT electron trigger, PID

Muon-Arm (-4<η<-2.5):

Muon trigger, tracking, PID

Smaller detectors (V0, T0, ZDC, SPD):

Trigger, centrality selection,

event plane rec.

ALICE apparatus

DCAL

PHOS

Countries: 41Institutes: 176Members: 1800

Detector:

Length: 26 meters

Height: 16 meters

Weight: 10,000 tons

TDR

Dedicated to measure

hadrons, electrons,

muons and photons

to cope with very high

multiplicities

8

ALICE performance

• Efficient low-momentum tracking — down to ~150 MeV/c

• Excellent particle identification (hadrons, leptons and photons)

• Excellent vertex capability (HF, V0, cascades, conversions)

• Di-jet trigger via combined calorimeters (EMCal – DCal)

• High precision muon measurement at forward rapidity


➢ v2 mostly driven by overlapgeometry

➢ higher orders mostly driven by fluctuations

(odd harmonics non-existent in averagegeometry)

➢ compare different systemsusing multiplicity as scaling variable

― finite vn in pp:

similar values as peripheral Pb–Pb/Xe–Xe― different geometry at given multiplicity:

→ v2 does not scale withmultiplicity

Anisotropic expansion

0

0.02

0.04

0.06

0.08

0.1

vn{2

}

0.12

(a)

0.16 PYTHIA 8 Hydro ALICE

pp pp p-Pb Xe-Xe Pb-Pb pp p-PbXe-Xe Pb-Pb

13 5.02 5.02 5.44 5.02 13 5.02 5.44 5.02 sNN

(TeV)0.14 v 2{2, || > 1.4}

v 3{2, || > 1.0}

v 4{2, || > 1.0}

102 103

N ch (|| <0.8)

0.08

0.06

0.04

0.02

0

0.1

0.16

v2{k

}

0.18 (b)

0.14 || < 0.8

T

0.12 0.2 < p < 3.0 GeV/c

Hydro ALICEXe-Xe Pb-Pb pp p-Pb Xe-Xe Pb-Pb

5.44 5.02 13 5.02 5.44 5.02 sNN

(TeV)

3-sub

v 2{4}

v 2{4}

v2{6}

v2{6}

2

2-sub

v {8}

2-subv2{8}

vn vs multiplicity

multiplicity

➢ quantify azimuthal anistropy by Fourier coefficients:v2 v3 v4

. . .

[arXiv:1903.01790]

ALICE Overview and Chinese Eff, Daicui Zhou, SJTU, Shanghai, June 3, 2019Daicui Zhou, ALICE Overview and Chinese Efforts in ALICE, June 3, 2019, SJTU, Shanghai 10

Charged

https://arxiv.org/abs/1903.01790

High-Precision Correlations of CorrelationsJH

EP

09

(20

17

)03

2P

RC

97

(20

18

)02

490

6

Symmetric cumulants Factorization ratios

How are vn and vm correlated? Do vn factorize in pT?

Characterization with unprecedented detail!

Daicui Zhou, ALICE Overview and Chinese Efforts in ALICE, SJTU, June 3, 2019, SJTU, Shanghai 11Daicui Zhou, ALICE Overview and Chinese Efforts in ALICE, June 3, 2019, SJTU, Shanghai 11

Charged

v2 vs. pT

• D0 mesons exhibit v2 >0 →charm quarks flow with medium

• Event Shape Engineering

– At fixed impact parameter, select shape of collision region

• Heavy flavour v2 “follows” shape fluctuations q2

D0 anisotropya

rXiv

:18

09.0

9371

20% largest q2

60% smallest q2

20% largest q2

Overview of the ALICE recent results, Daicui Zhou, Fudan, Shanghai 12

60% smallest q2


• Spectator charge causes large magnetic

field (~1018 Gauss)

– Aligns spins

• Domains with non-zero topological charge

(local) → chirality flip

• Leads to charge separation

• Experimental correlator

– Same sign = signal

– Opposite sign = control

Overview of the ALICE recent results, Daicui Zhou, Fudan, Shanghai 13

Chiral Magnetic Effect


• Signal observed increasing with increasing

centrality

• Magnitude similar at 0.2 TeV (STAR) and2.76 TeV (ALICE)

• Magnitude similar in Pb-Pb and p-Pb

• Issue: Large backgrounds due to local charge

conservation (resonance decays, momentum

conservation, parton fragmentation)

Earlier ResultsP

RL

110

(20

13

),01

230

1

112 vs. centrality

Overview of the ALICE recent results, Daicui Zhou, Fudan, Shanghai 14Daicui Zhou, ALICE Overview and Chinese Efforts in ALICE, June 3, 2019, SJTU, Shanghai 14

• Event shape engineering, modelling of magnetic

field + initial state models allows limit on CME

• fCME = maximal signal contribution in correlator

– Limit set on signal 7-33% at 95% C.L.[PLB 777(2018)151,PRC 97(2018)044912]

• Interesting opportunity: Isobar run at RHIC

– Test Z2 magnetic field dependence

• Sub-percent precision with run 3 and 4

Now & FutureP

LB

77

7(2

01

8)1

51

fCME vs. centrality


• Passing nuclei → strong magnetic field → C-odd directed flow v1

• Electric field → same effect with opposite direction

• Measured for hadrons and D mesons

– Earlier formation time→ sensitivity to stronger magnetic field

D Directed Flow

Theory expects that B dominates,

but opposite slope measured

(with limited significance)

Signal larger


J/ψ anisotropy

v2

v3

• J/ v2 well measured：-- Forward in di-muon channel

➢ J/ψ flows ⇒ coupling to medium (consistent with recombination)

➢ ordering: v2(J/ψ) < v2(D0) < v2(h±)

➢ First evidence for v3 > 0 (3.7 )

arXiv:1811.12727


ϒ anisotropy

Tp (GeV/c)

2 4 6 8 10

v2

−0.05

0

0.05

0.1

0.15

0.2

(1S), KSU model, arXiv:1809.06235

ALICE Preliminary Pb−Pb sNN = 5.02 TeV

5−60%2.5 < y < 4

Inclusive J/

(1S)

ALI−PREL−314841

v2 (1S), TAMU model, PRC 96 (2017) 054901

Centrality

5−60% 5−20% 20−60%

v2

−0.05

0

0.05

0.1

0.15(1S)

Inclusive J/

ALICE Preliminary Pb−Pb sNN = 5.02 TeV

2 < p < 15 GeV/cT

2.5 < y < 4

ALI−PREL−314845

➢ first measurement of v2 for Υ: consistent with 0

first particle measured not to have flow!

➢ not dragged along by flow of medium,

not produced by recombination

Pb–Pb 2018!


• HI collision more than superposition of nucleon- nucleon collisions

with incoherent fragmentation?

Hadron energy Loss

dN / dpTpp

Ncoll

dN / dpTAA

AAR =

RAA = 1 → no modification

RAA = 1 → medium effects

RAA vs. pT Significant suppression of hadrons w.r.t pp

19

Hint of ordering of energy loss:

➢ charged hadrons

➢ D mesons

➢ Ds

➢ Λc

→ mass-dependent energy energy loss

Daicui Zhou, ALICE Overview and Chinese Efforts in ALICE, June 3, 2019, SJTU, Shanghai

⚫ Significant energy loss

– Consistent picture of charged and D jets, and hadrons

⚫ Quark-mass dependent energy loss involving b

Heavy quark and jet energy loss

B→ J/

D

20

D jetsCharged jetsD mesons

PRC93,034913(2016) pT (GeV/c)

⚫ described by models implementing mass-ependent energy loss


Jet energy loss

➢ also jets are strongly suppressed in medium➢ excellent tool to study medium interaction

JetsJets


• Characterize and understand parton-medium

interactions by exploring splitting phase space

• First splitting at small angles:– Pb-Pb jets ~ vacuum reference

• First splitting at large angles:

– Overall suppression, steeper zg distribution

Jet Substructure

R < 0.1

22

R > 0.1


Small Systems

JHEP09(2010)091ALICE

p-Pb

PLB719(2013)29

p-Pb

23

PLB726(2013)164

P-Pb

Double ridge resembles the structure attributed to collectiveflow in p-Pb

Clear indication for mass ordering in p-Pb resembles Pb-Pb and supports “flow” picture

➢ Models including hydrodynamical expansion

can describe the observations

Alternative interpretations:

➢ CGC: many-gluon correlations

(Dusling, Venugopalan, PRD 87 (2013) 094034)

➢ MPIs and “colour reconnections”(Ortiz et al, PRL 111 (2013) 042001

pp

Nch

Collective phenomena observed

in pp and p-Pb collisions have

caused a paradigm shift.


Strangeness production

NEW

24

Nature Phys.13(2017)535

➢Particle identification capabilities down to low pT

➢ Integrated particle yields

➢Fully characterized by thermal model:

―baryon chemical potential β=0

―temperature T ≈ 153 MeV

―volume V ≈7000 fm3

(for Pb–Pb √sNN

= 5.02 TeV)

➢Thermodynamic description ↔

➢Microscopic fundamental interactions

➢Particle ratios as function of multiplicity

show smooth evolution from pp to Pb–Pb

collisions, transition between different

mechanisms?

Yields normalized to pions


• Run 3 can reach extremely rare (10-11) pp events

– 200 pb-1 | Sampling 1013 events

• Significant overlap between pp and PbPb

– In multiplicity up to ~65% centrality

• If pp behaves HI, we shall see “standard” HI physics

– Including jet quenching if effects driven by final state

– If not, we can see the differences

• In addition: MB sample for low-multiplicity limit

– What is smallest droplet of matter showing

collective behavior?

– Origin of collectivity in few particle system?

(color reconnection, gluon interference, escape, …)

Understanding Small Systems

Pb-Pb

p-Pb

pp

Today

65% central

14-16 <Nch>

>25k events

P(Nch) vs. Nch

25Daicui Zhou, ALICE Overview and Chinese Efforts in ALICE, June 3, 2019, SJTU, Shanghai

LHC run 2

Upgrades “LHC LS2”• LHC: collimators + injectors

• ALICE: Tracking, DAQ (rate x100)

LHC Run 3 + 4 (numbers for Pb-Pb)

• L = 6 ·1027 cm-2s-1 ~ 50 kHz rate

• 10 nb-1 (ALICE)

2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029

Upgrades “LHC LS3"

26

Precision measurements of ➢heavy flavour and quarkonia➢ Jets➢ low-mass dileptons➢ light (hyper-)nuclei

Future physics goals


ALICE detector upgrade27

Increase of luminosity and improve vertexing and tracking at low-pT


LS2 upgradesobjective: operation at high interaction rates (50 kHz of Pb–Pb collisions)

⇒ continuous (i.e. untriggered) read-out for core detectors

Time Projection Chamber

(not toscale)

GEM readout chambers

Muon Forward Tracker

MAPS-based forward tracker

Inner TrackingSystem

Monolithic Active Pixel Sensors

Forward Interaction Trigger

Cherenkov + scintillator


Construction & commissioningTPC ITS Inner/Outer Barrel

Half-layer0 Half-Layer1 Half-Layer2


Beyond LS2ITS3

➢ wafer-sized sensors

➢ on-chip powerdistribution

➢ cooling by forced air flow

➢ significant reduction of material budget

FoCal

➢ forward region so far uninstrumented

➢ FoCal-E: photons and π0s

➢ FoCal-H: photon isolation and jets

➢ constrain gluon PDFs at low x


• Legacy of results from first 8 years of heavy-ion collisions at the LHC

– Participant picture, medium properties, energy Loss in 100 GeV regime, quarkonia

regeneration, and so on.

– Paradigm shift of understanding of small collision systems

• Next decade expects 100x larger data sample

– Macroscopic long-wavelength QGP

– Microscopic parton dynamics underlying the QGP properties

– Investigate unified picture of particle production from small to large systems

Opportunities detailed in community document: arXiv:1812.06772

Summary



Chinese efforts in ALICE

• Hardware contributions

• Physics contributions

• Perspective HL and HE running at the LHC


Hardware contributions⚫ PHOS FEE development

⚫ A DCAL supermodule development

⚫ DCAL/EMCAL/PHOS SRU development

⚫ ITS upgrade + MFT upgrade

ALICE Experiment41 Countries177 Institutes1800 Members

PHOSDCal

Muon Spectrometer

-2.5 >eta > -4

Physics Goal

Detection of QGP signal and properties at TeV energiesDetector:

Length: 26 meters

Height: 16 meters

Weight: 10,000 tons

33

China Team:

CCNU, CIAE, HUST, HTU,

USTC and Fudan/SINAP

Physics on:

• Photons and jets

• Heavy-floavours

• Exotic particle properties

34

PHoton Spectrometer(PHOS) FEE

⚫ Development of full PHOS FEEs (R&D, production and commissioning)；

⚫ Development of three sets of software of PHOS (FEE, Triger and RCU);

⚫ Objective: dedicated to measurement of photons and jets

FEE arrayFront-end electronics (FEE)

34

35

PHOS FEE R&D, production and commissioning

R&D in 2002 - 2005

First batch of FEEs delivered in Jan. 20063nd batch of FEEs delivered in June 2008

FEE Review Meeting, on May 30/31 2005, Wuhan

FEE and PHOS installation, 2008, p2/LHC 35

2009年3月3日，兰州

PbW04 crystal

APD CSPPWO

Readout

光子探测器模块重12吨 PWO array

TRU

联合安装和调试PHOS超级模块 FEE array一个超级模块 36

FEE

Contribution on PHOS（red arrow）

ALICE-DCAL Proposal

PHOS

DCAL

● ALICE Di-jet Electromagenetic Calorimeter (DCAL) proposed by China and Japan team

in 2009 and approved by ALICE after 6 months；construction in two years and

taking data from 2015

● Measure energy of photon and jet precisely

Je

t

γ

jet

jet

π0

γ－jet

Jet-jet

π0－jet


代表性成果 1-1: 研制双喷注电磁量能器的一个超级模块

38

Di-jet EMCAL(DCAL) contribution

SRU development for EMCAL /DCAL /PHOS

39

◼ Scalable Multi-channel parallel

p2p transmission mode, high

Speed, low noise, high stability

◼For DCAL firstly; then applied

to EMCal; Improved for PHOS

◼ Building a SRU prototype at Lab

For monitoring the on site at CERN

◼ Published on Nucl. Inst. Meth.

Phys. Res. A (2014), pp. 157-162

39

Neutral pion measurement in pp and Pb-Pb collisionsEur. Phys. J. C77 (2017) 339

• Neutral pion: measured up to pT = 40 GeV/c

➡Thanks to the shower shape method for high-pT

π0 identification

• New constraint on model prediction

➢ Suppression increase with centrality, achieve to a factor about 10 in most 5％central collisions at high pT -- two times as larger as at RHIC

➢ Larger energy loss resulted by highly denser QCD medium at LHC

Eur. Phys. J. C 10 (2014) 3108


π0–hadron correlation in pp and Pb–Pb collisions

• Measurement has been extended to lower pT w. r. t. di-hadron correlations

➡Near side enhancement: modification of jet fragmentation, quark- / gluon-jet ratio

and/or the bias on parton pT spectra…

➡Away side suppression at high pT: hard parton energy loss

➡Away side enhancement at low pT: favor the jet-medium excitation scenario

➡Provided baseline for the study of γ-hadron / jet correlations

Phys. Lett. B763 (2016) 238

Away side

Near side


Jet production in pp and Pb-Pb collisions

• Charged-particle jet RAA at 5.02 TeV

• Consistent with RAA of full-jet RAA at 2.76 TeV

• Cross section ratio measured in pp collisions

• Jet structure in vacuum — consistent with model predictions• Baseline for heavy-ion collisions — understanding of the medium modified jet

fragmentation

• pp reference: paper proposal has been accepted by ALICE collaboration

New for QM’18


HF muon production in LHC RUN-I

• Observed strong suppression of yield of open heavy-flavour decay muons in central Pb–Pb

collisions w. r. t. pp collisions

➡Nuclear modification factor in p–Pb collisions consistent with unity at high pT

➡Strong suppression is due to the hot medium effects

• Positive v2 of open heavy-flavour decay muons at forward rapidity

➡Significant interaction of heavy quarks with the QCD medium in a wide rapidity range

• Phys. Lett. B708 (2012) 265

• Phys. Lett. B753 (2016) 41• Phys. Rev. Lett. 109 (2012) 112301

• Phys. Lett. B770 (2017) 459


HF muon production in LHC RUN-II

44

• Production of open heavy-flavour decays muons was measured up to pT = 20 GeV/c

• Reduced uncertainty w. r. t. RUN-I measurement — new constraint on model

predictions

• Corresponding paper proposals have been received by ALICE

➡Target journal: Phys. Lett. B (pp collisions) and Phys. Rev. Lett. (Pb–Pb collisions)

• Xe–Xe at 5.44 TeV: compatible with Pb–Pb at 5.02 TeV with similar event multiplicity

ALICE-China group has dominated almost all of HF decay muon

measurements in ALICE

Xe–Xe at 5.44 TeV

New for QM’18

Pb–Pb at 5.02 TeV

Production of D mesons

Core contribution of ALICE-China group• First measurement of D meson production cross section in pp collisions at LHC energies• First measurement of D meson RAA in Pb–Pb collisions in ALICE LHC RUN-II

JHEP 1201 (2012) 128


JHEP 1810 (2018) 174

Collectivity of (Multi-)strangeness

46

➢ First observation of significant parton collectivity at the LHC, indicating the QGP

produced in Pb-Pb collisions closing to idea fluid

➢ Scaling violation of number of quarks with level ~20% observed firstly at the LHC

JHEP 1506, (2015) 190


Strangeness enhancement

• Smooth evolution of particle ratios with

multiplicity

• Strangeness enhancement considered

defining feature of heavy-ions — now also

seen in high-multiplicity pp / p–Pb!

• Not reproduced by traditional soft QCD

models (e.g. Pythia)

➡Challenges universality and factorization of

fragmentation

➡Study of hadronization mechanisms

• Multiple Parton Interactions lead to

densely packed strings in the transverse

plane (e.g. EPOS and DIPSY)

Nature Physics 13 (2017) 535


Chinese-team effort on ITS upgrade

48

Chinese team involved in R&D of the MAPS; Taking 20% of chip module assembly, installation and calibration of upgrade ITS

7 layers (10 m2) silicon pixel (MAPS)

sensor traker from 22-406 mm to IP with

spatial resolution O(5 um)

Bs, Bc，Λb , b-jet measurement available

ITS upgrade HIC assembly at CCNU

48

Involvement on Muon Tracker Forward (MFT)

49

More precise measurements of heavy

flavours and low mass dileptons


ALICE Chinese Team●华中师范大学（CCNU）

transport and collective properties of QGP

●中国原子能科学研究院（CIAE）

Cold nuclear effects

● 中科院上海应用物理研究所（SINAP）

Exotic particle properties in nuclear matter

●中国科学技术大学（USTC）

Charmonia and collectivities of QGP environment

● 华中科技大学（HUST）

Readout electronics

● 湖北工业大学（HUT）

Readout electronics


谢谢！

Thanks


Backup


v3

arXiv:1804.02944

v2

arXiv:1805.04390

54

v4

conditions and medium propertiesp differential v constrains initialT n

v2

Inclusive charged particle

anisotropic flow fluctuations:

vn ratios constrain medium

properties: /s, /s

v4

v2

Overview of the ALICE recent results, Daicui Zhou, Fudan, Shanghai

High-Precision Measurements of Collective Flow


J/ψ anisotropy

v3 (0-50 % integrated)

Tp (GeV/c)

2 4 6 8 10 12

v3/v

2

0

0.5

1 Pb-Pb sNN = 5.02 TeV 5-40%

Tp (GeV/c)

2 4 6 8 10 12

Inclusive J/, 2.5<y<4.0, ALICE

Prompt D0, |y |<1.0, CMS

h, ||<0.8, ALICE

10-50%

v3/v2: 5-40 % (left), 10-50 % (right)

➢ v3/v2 significantly smaller for J/ψ

➢ Underlines importance of regeneration component

[arXiv:1811.12727]



➢ How does charm recombine from the QGP?

– Baryon/meson ratios Ds/D, c/ D0,b/B

– Very challenging: e.g.c c ~ 60 m

c arX

iv:1

80

9.1

0922

– c /D0 increases considerably from pp/p-Pb to Pb-Pb

→favours recombination from quarks in the medium

(instead of primordial production)

56

➢ c composed of udc

(heavy quarks produced early in the collision)

➢First measurement at LHC

Recombination:

➢ similar fect seen for J/Ψ


• LHC provided a few hours of Xe-Xe collisions in 2018 (as a proof-of-principle)

– Resulted in a number of results and publications

Xe-Xe

arXiv:1805.04432

PL

B7

84(2

018

)82

Charged-particle density

Anisotropic flow


• RAA suppression Pb-Pb vs. Xe-Xe

– weaker at same centrality

– identical at same dN/d or Npart

for central events

– deviations above 30% centrality but

within uncertainties

Xe-Xe

PLB788(2019)166Centrality

58

Centrality


Overview of recent ALICE results and Chinese efforts in ALICE · 6/3/2019 · Overview of recent...

Documents

Transcript of Overview of recent ALICE results and Chinese efforts in ALICE · 6/3/2019 · Overview of recent...