Correlation between eventmultiplicity and observed collectiveflow周代梅华中师范大学粒子物理研究所
Correlation between event multiplicity and observed collective flow 周代梅 华中师范大学粒子物理研究所 1
ContentsIntroductionCollective flow and higher harmonicsResults & discussionsConclusion2
Contents • Introduction • Collective flow and higher harmonics • Results & discussions • Conclusion 2
L. IntroductionThe chargeparticleemittedfromthefireballcreatedinrelativisticnucleus-nucleuscollisionexhibittransversecollectiveflowRepresented by the elliptic flow parameter (v_2) andother harmonic parameters (v_n, n=0,1,3,4,...)The expected phase transitionto QGP should have adramatic effect on those harmonic parametersThe study of collective flow can provide information onthe initialstate dynamics and the degree of equilibrationattainedinheavy-ioncollisionsV2 play crucial role in the evidence of QGP3
I. Introduction The charge particle emitted from the fireball created in relativistic nucleus-nucleus collision exhibit transverse collective flow Represented by the elliptic flow parameter (v_2) and other harmonic parameters (v_n, n=0,1,3,4,.) The expected phase transition to QGP should have a dramatic effect on those harmonic parameters The study of collective flow can provide information on the initial state dynamics and the degree of equilibration attained in heavy-ion collisions v2 play crucial role in the evidence of QGP 3
Il. Collective flow and higher harmonicsA, Present statusIn basic paper of PR,C58(1990)1671,startfromtriple differential distributiond'Nd?N1+Z2v, cos(n(μ-y,))F[1 +d'p- 2元 prdydprn=1and define that, wherecestrintdica.tsanaverageoverallparticleinallevents4
A, Present status In basic paper of PR,C58(1990)1671,start from triple differential distribution 3 2 3 1 1 [1 2 cos( ( ))] 2 n r T T n d N d N E v n d p p dydp = = + − and define that , where <> indicates an average over all particle in all events. cos[ ( )] n r v n = − II. Collective flow and higher harmonics 4
Vo : isotropic flowvi : first harmonic, directed flow2 : second harmonic, elliptic flow(elliptic component )Vn (n=3,4,...): higher harmonicsFor the particle number distribution, the coefficientPxp,V22+02V1PTPTPThat is widely accepted in theoretical calculations5
𝑣0 : isotropic flow 𝑣1 : first harmonic, directed flow 𝑣2 : second harmonic, elliptic flow (elliptic component） 𝑣𝑛 (n=3,4,.): higher harmonics For the particle number distribution, the coefficient 𝑣1 = 𝑝𝑥 𝑝𝑇 𝑝𝑇 = 𝑝𝑥 2 + 𝑝𝑦 2； 𝑣2 = 𝑝𝑥 𝑝𝑇 2 − 𝑝𝑦 𝑝𝑇 2 That is widely accepted in theoretical calculations 5