Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 1

First results on particle correlations from ALICE

Dariusz Miśkowiec, GSI Darmstadt and EMMI

for the ALICE Collaboration

why two-pion correlationstwo-pion correlations at 900 GeVfirst look at 7 TeV datatry harder: high-pT correlationssummary

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 222

transverse expansion pT spectra look thermal but boostedlongitudinal expansion source size depends on pT

Collectivity in nuclear collisions

collective transverse velocity

apparent source of pions with given (y,pT)

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 33

temperature and transverse flow when energy conservation treated properly

3

Mike Lisa, CERN Theory Phenomenology Seminar, 16-Oct-2009

Transverse expansion

transverse expansion seems to be there even in very peripheral nuclear collisions

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 4

Pion source size from STAR

STAR, arXiv:1004.0925 [nucl-ex]STAR, Phys. Rev. C 80 (2009) 24905

pT dependence of pion source size similar in nuclear and pp collisions

Au + AuCu + Cu

p + p

(various ways of fitting)

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 5

identical-pion correlation analysis technique (HBT)

peak width ~ 1 / source size

pion source size accessible experimentally

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 6

Two-pion correlation functions in A+A and p+p collisions

baseline shape is the challenge in p+p data

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 777

pp at sqrt(s) = 900 GeV250 k minimum bias events10 days starting on Dec 6, 2009

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 8D. Miskowiec, ALICE femto meeting 2010-03-22 88

identical pion correlation functions

Bose-Einstein peak clearly visible

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 9D. Miskowiec, ALICE femto meeting 2010-03-22 99

Unlike-sign pion correlation function

Coulomb and K0S peaks visible

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 10

Multiplicity and transverse momentum dependenceidentical pions unlike-sign pions

baseline has to be treated properly

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 11

Multiplicity dependence

visible dependence in pp HBT radii depend on multiplicity rather than on collision geometry

for comp.: nuclear collisionsM. Lisa, Ann. Rev. Nucl. Part. Sci. 55, 357

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 12

Transverse momentum dependence

no significant dependence on transverse momentum

for comparison: in nuclear collisions

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 13

Dependence on the baseline assumption

but: transverse momentum dependence is sensitive to the baseline shape assumption

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 14

pp at sq

rt(s)

= 7 TeV

180 M

minim

um bias ev

ents

from M

arch 31

till n

ow

120 M events used for this talk

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 15

pp at sqrt(s) = 900 GeV

7 M minbias events

on May 2-3, 2010

2.1 M events used for this talk

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 16

7 TeV and new 900 GeV data

high-q baseline flatter at 7 TeV

identical pion correlations

120 M events at 7 TeV2.1 M events at 0.9 TeV

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 17

π+π - correlations at 7 TeV

K0S

ρf0 f2

ω

Coulomb

rich resonance structure

low-q baseline steeper at 7 TeV origin: jets

high-q baseline flatter at 7 TeV origin: momentum cons.

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 18

Non-identical particle correlations from pp at 7 TeV

C(qout ) asymmetry -- another handle on transverse flow

pion - kaon

pion - proton

K*

Δ

Λ

example: Pb+Au at 17.2 GeV CF’s from CERES

π+π - π- p π+p

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 19

Summary

HBT radii at 900 GeV depend on multiplicity no strong dependence on transverse momentumcorrelation baseline of crucial importance

backup

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 212121

transverse momentum dependence of Rside

Tm

RpRf

Gside 2

1

)(

Rlong fTmt

K2(mt /T)K1(mt /T)

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 222222

baseline slope significant at 0.9 TeV and abovestudy by Adam Kisiel

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 23

7 TeV, identical pions

low mult

high mult

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 24

High stat 900 GeV from 2010, identical pions

low mult

high mult

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 25

7 TeV, unlike-sign pions

low mult

high mult

Dariusz Miskowiec, Particle correlations in ALICE, Physics at the LHC, Hamburg, 10-Jun-2010 26

High stat 900 GeV, from 2010 unlike-sign pions

low mult

high mult