160 likes | 177 Views
This study investigates the azimuthal correlation of hadrons in a partonic/hadronic transport model. The analysis method and results are discussed, with a focus on the hadronic phase, freeze-out, and quark-gluon plasma properties. The study also explores the effects of thermalization and the formation of Mach-like cone structures in high-energy nucleus-nucleus collisions.
E N D
Azimuthal correlation of hadrons in a partonic/hadronic transport model Guo-Liang Ma • Background introduction • Model introduction • Analysis method • Results and discussions • Conclusion
hadronic phase and freeze-out QGP and hydrodynamic expansion initial state pre-equilibrium hadronization High Energy Nucleus-Nucleus Collisions Physics: 1) Parton distributions in nuclei 2) Initial conditions of the collision 3) a new state of matter – Quark-Gluon Plasma and its properties 4) hadronization
Associated particles On away side: pT(assoc) > 2 GeV/c Hard associated particles → suppression 4 < pT(trig) < 6 GeV/c pT(assoc) > 0.15 GeV/c Soft associated particles→ enhancement Di-hadron correlations
<pT> from away jets near side SOFTENED BROADENED <pT> from medium decay thermalization??? away side BROADENED SOFTENED Soft Associated particles on Away side (thermalization) What happens to a hard probe that traverses a colored medium? soften + broaden =?= thermalization
Possible interpretations of mach-like cone structure Wake Effect or “sonic boom” Θemission= arccos (cs/c) hep-ph/0411315 Casalderrey-Solana,Shuryak,Teaney nucl-th/0406018 Stöecker Hep-ph/0503158 Muller,Ruppert nucl-th/0503028A. K. Chaudhuri Cherenkov gluon radiation Θemission= arccos (1/n(p)) PRL 96, 172302 (2006) Koch, Majumder, X.-N. Wang Correlation of Jet with flowing medium hep-ph/0411341 Armesto,Salgado,Wiedemann
AMPT model a multi-phase transport model (2) Melt AMPT (1) Default AMPT
Mix-event Technique • (1) Get raw correlation signal in same event • (2)Get respective background by mixing events in same centrality • (3)Get correlation by removing background with ZYAM method Background Subtracted signal
correlations from AMPT (3<pTtrigger<6GeV/c ,0.15<pTassoc<3GeV/c) (1) ▲melt after hadron cascade (2) ●melt before hadron cascade (3)◆default after hadron cascade (4)★default before hadron cascade (5) ■Star Data 0-5% (4-6)*(0.15-4)GeV/c factor=1.58 Au+Au 200GeV (0-10%)
Jet remnants character from AMPT Au+Au 200GeV
0-10% D 10-20% 20-40% 40-90% Mach-like cone Structure in AMPT model correlations in Au+Au 200GeV (2.5<pTtrigger<4GeV/c ,1<pTassoc<2.5GeV/c)
background subtracted 3-particle correlation signal mix-event technique Three-particle correlations in AMPT
Three-particle correlation density • 3-particle correlation density definition:
Parton cascade effect on 2- and 3- particle correlation (1)hadron cascade mechanism also can produce 2- and 3-particle correlation, but it can not give big enough splitting parameters. (2) the parton cascade mechanism is essential for describing the amplitude of experimental mach-like structure
Conclusion • Di-hadron correlations can be produced by a multi-phase transport model(AMPT). • Mach-like structure is born in the partonic process and further developed in hadronic rescattering process. • hadron cascade mechanism can produce di-hadron correlation, but it can not give big enough splitting parameters. • Cone , deflected and center 3-particle correlations all exist in the central Au+Au collisions, however center 3-particle correlation become more dominant with the decreasing of Npart .