120048813
A criterion for the order of QGP phase transition
Based on the extended Ginzburg-Landau model, it is shown that the dependences of the scaled factorial moments ln Fq on phase space intervals are different for first- and second-order QGP phase transitions. When ln Fq are fitted to polynomials of X ≡ δ13, the relative sign between the fitted coefficients can be used to judge the order of phase transitions.
119949182
Systematic study for grey particles in relativistic nucleus + emulsion (Ag) interactions
The hadronic and string cascade model and the corresponding event generator LUCIAE are used to study systematically the production of the grey particles in (14.6, 60 and 200A GeV)0 + Em, (2004 GeV)Si + Em, (200A GeV)S + Em and (11.6A GeV)Au + Em reactions. The dependences of the mean multiplicity, the multiplicity distributions and the polar angular distributions of the grey particles on the incident energy, the projectile mass and the collision centrality observed in emulsion experiments, respectively, are all reproduced by LUCIAE calculations. In addition the effects of the rescattering on the grey particle production are also investigated.
37119712
Heavy Flavor Production at PHENIX at RHIC
A study of heavy flavor production in different collision systems in various kinematic regions presents an opportunity to probe cold nuclear medium and hot dense matter effects. Results from the PHENIX experiment on J/ψ and open charm production in Au+Au and Cu+Cu collisions at sNN =200 GeV are presented. The data show strong J/ψ suppression in central AA collisions, similar to NA50 results, and strong suppression in high pT open charm production. The J/ψ production in Au+Au and d+Au collisions is compared to understand the cold nuclear medium effects. The data show significant cold nuclear effects in charm production in d+Au collisions at forward and backward rapidity ranges.
119042314
CHARM PRODUCTION AT LARGE RAPIDITIES IN p+p AND d+Au COLLISIONS AT PHENIX AT RHIC
We study charm production through dimuon and single muon measurements at forward and backward rapidities in p+p and d+Au collisions with the PHENIX muon detectors. We also compare open charm to $J/\psi$ yields in the forward and backward rapidities in d+Au collisions and study the origin of the large forward and backward asymmetry in open charm production observed by the PHENIX experiment.
120209602
Longitudinal Double Spin Asymmetries in Heavy Flavor Production in Polarized p+p Collisions at s = 200 GeV
One of the main goals of the RHIC spin program is to determine the contribution of gluons to the proton spin. At RHIC energies, heavy quark (charm and beauty) production is expected to be dominated by gluon‐gluon interactions, so a measurement of the double longitudinal spin asymmetry ALL in heavy quark production in polarized p+p collisions directly probes the polarized gluon distribution inside the proton. We present the latest results on an ALL measurement for J/Ψ and open charm production measured by the PHENIX detector.
198138925
Oscillations of moments in high-energy nucleus-nucleus collisions
The definitions of density function and moment of multiplicity distribution are introduced, and the method of moment analysis in e+e- and proton-proton (pp) interactions is extended into nucleus-nucleus (AA) interactions. We analyze the data for relativistic nucleus-nucleus collisions and calculate the values of Hq for charged particle multiplicity distributions, by which we study systematically the dependences of Hqon incident energy, mass of colliding system, pseudorapidity interval, centrality and truncation of multiplicity. We compare the oscillation structures induced by e+ e-, pp and AA interactions, and the comparison and analysis are carried out between experimental data and QCD prediction. The latest results are given in this paper.
41015931
Jet tomography of quark gluon plasma
Recent experimental measurements of high pT hadron spectra and jet correlation at RHIC are analyzed within a parton model which incoporates initial jet production and final propagation in heavy-ion collisions. The suppre-sion of single hadron spectra, back-to-back correlation, their centrality dependence and azimuthal anisotropy point to a dense matter with an initial parton density about 30 times of that in a cold heavy nucleus.
121472375
Mini-jets and multiplicity fluctuation in small rapidity intervals
Abstract The multiplicity fluctuation of particles in small rapidity intervals from mini-jets in high-energy hadron-hadron collisions are considered and a power-law behavior is found. An increase of the observed factorial moments with P T of the jets is expected. However, the fluctuation becomes smaller for larger total multiplicity due to the contributions from multiple mini-jets production.
123350613
Formation of disoriented chiral condensates through quenching and annealing
Abstract We demonstrate that the chiral phase transition is automatically incorporated in the numerical simulations of the classical equations of motion in the linear σ-model. We find that domains of disoriented chiral condensate with 4–5 fm in size can form through a quench while an annealing leads to domains of smaller sizes. We also demonstrate that quenching cannot be achieved by relaxing a chirally symmetric system through expansion. Furthermore, we point out that the order of the phase transition has little significance for the domain formation.
14150714
Single production of the vector-like top quark in the littlest Higgs model at TeV energy $e^{-}\gamma$ colliders
The new colored vector-like heavy fermion T is a crucial prediction in little Higgs models, which plays a key role in breaking the electroweak symmetry. The littlest Higgs model is the most economical one among various little Higgs models. In the context of the littlest Higgs model, we study single production of the new heavy vector-like quark via eγ collisions and discuss the possibility of detecting this new particle in the TeV energy ee collider(LC). We find that the production cross section can vary in a wide range(10 − 10fb) in most parameter spaces. For the favorable parameter spaces, the possible signals of the vector-like top quark T can be easily detected via eγ collisions in future LC experiment with √ s = 3TeV and £ = 500fb. PACS number(s): 12.60.Cn, 14.70.Pw, 14.65.Ha ∗E-mail:hnxxlyb2000@sina.com
121590045
Two particle correlations in jets and triggered distributions in hot and cold matter
The modification of the correlation between high p T particles produced in association with trigger particles from jets emanating from a heavy-ion collision is shown to be a valuable probe of the matter produced in such collisions. While the minimal modification on the same side as the trigger is consistent with the picture and parameters of partonic energy loss, the possible observation of Cherenkov like correlations on the away side leads to the possibility of the existence of composite structures in the excited matter.