The Resonance Production In Au+Au Collision At RHIC

Quantum chromodynamics (QCD) predicts that the phase transition of hadronic matter toquark gluon plasma (QGP) would happen at extremely high temperature and great density. Thestudy of this state of matter is important to understand the basic building blocks of matter and theearly evolution of our universe: the first hundred microseconds or so. Collisions of heavy ionswith ultra-relativistic collisional energy can provide the extreme condition of QGP creation inlaboratory. The running of Relativistic Heavy Ion Collidier (RHIC) at the Brookhaven NationalLaboratory in2000has cumulated rich experimental data which greatly promote the study ofQGP creation and its properties.The short-lived resonances are efficient tools of probing the properties of the hot and densemedium produced in relativistic heavy ion collisions. It is known that the evolution of heavy ioncollisions includes the following sub-processes, i.e. the primordial creation of QGP, thesubsequent QGP evolution, hadronization and final state hadronic re-scatterings. The propertiesof final hadrons are synthetic results of all these processes. The lifetime of the resonance is abouta few fm/c, which is less than (or roughly the order of) the lifetime of the system formed inheavy ion collisions. After QGP hadronization, but before the interactions of hadrons cease, theinitially produced resonances and stable hadrons will undergo a hadronic rescattering stage. Theresonance might be destructed by rescattering with other hadrons and also be regenerated by thecollisions of other hadrons, and decay daughter particles of resonance are kicked by otherhadrons causing the signal loss. The physical properties of resonances, e.g. their masses andwidths, might be modified by the surrounding medium. In addition, the yields and momentumspectra of resonances might be changed. The experimental reconstructed resonances aresynthetic results of the hadronization and hadronic rescattering effects. The studies of hadronresonances in relativistic heavy ion collisions have provided rich data for the production ofK*0， Σ*resonances at the RHIC and SPS energies. A systematical study of the resonanceshould be capable of further test the quark combination mechanism of the hadron production atQGP hadronization in heavy ion collisions.In this paper, we apply a quark combination model developed by Shandong group (SDQCM)for hadronization of the hot ant dense quark matter and A Relativistic Transport (ART) model forthe hadronic rescattering process to study theK*0production in relativistic heavy ion collisionsat RHIC200GeV and62.4GeV. Firstly, we compare directly the hadronization results given bySDQCM with experimental data to see the magnitude of hadronization exhibited in the finalobservation. Secondly, we further consider the effects at RHIC200GeV and62.4GeV and time span of hadronic stage for the system produced at high RHIC energies.The work contains two aspects as follows:(Ⅰ) The study of yields andPT spectra ofK*0andΣ*in central Au+Au collisions ats NN=200GeV. We study the various stable hadronsPT spectra at s NN=200GeVofAu+Au central collision using the SDQCM, and get the yield andPT spectra of directlyproductK*0at hadronization. We investigate the dependence of theK*0yield on thehadronization parameter V/P ratio. We find that the yield ofK*0by hadronization is higher thanthe experimental data in the lowPT region. Then we use the ART model to study the effects oftime span of final state hadronic rescattering process on the yield andPT spectrum ofK*0, getthe yield andPT spectra of final stateK*0, and ensure the hadronic stage time. We usingSDQCM study themT ofΣ*at s NN=200GeVof Au+Au central collision. Then we predicttheν2ofΣ*.(Ⅱ) For further understanding the production ofK*0, we study the various stable hadronsPT spectra at s NN=62.4GeVof Au+Au central collision using the SDQCM, and get the yieldandPT spectra of directly producedK*0. Then use the ART model to treat the rescattering ofhadrons, get the yield andPT spectra of final stateK*0, and ensure the hadronic stage time.Then we using SDQCM predict thePT spectra ofΣ*at s NN=62.4GeV.