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Chiral Phase Transition in Linear Sigma Model with Nonextensive Statistical Mechanics
https://repo.scoap3.org/record/22540
From the nonextensive statistical mechanics, we investigate the chiral phase transition at finite temperature T and baryon chemical potential μB in the framework of the linear sigma model. The corresponding nonextensive distribution, based on Tsallis’ statistics, is characterized by a dimensionless nonextensive parameter, q , and the results in the usual Boltzmann-Gibbs case are recovered when q→1 . The thermodynamics of the linear sigma model and its corresponding phase diagram are analysed. At high temperature region, the critical temperature Tc is shown to decrease with increasing q from the phase diagram in the (T,μ) plane. However, larger values of q cause the rise of Tc at low temperature but high chemical potential. Moreover, it is found that μ different from zero corresponds to a first-order phase transition while μ=0 to a crossover one. The critical endpoint (CEP) carries higher chemical potential but lower temperature with q increasing due to the nonextensive effects.Zhang, Ben-WeiWed, 29 Nov 2017 21:16:13 GMThttps://repo.scoap3.org/record/22540urn:ISSN:1687-7365Hindawi2017-11-29Nuclear suppression of the ϕ meson yields with large pT at the RHIC and the LHC
https://repo.scoap3.org/record/21283
We calculate ϕ meson transverse momentum spectra in p+p collisions as well as their nuclear suppressions in central A+A collisions both at the RHIC and the LHC in LO and NLO with the QCD-improved parton model. We have included the parton energy loss effect in a hot/dense QCD medium with the effectively medium-modified ϕ fragmentation functions in the higher-twist approach of jet quenching. The nuclear modification factors of the ϕ meson in central Au+Au collisions at the RHIC and central Pb+Pb collisions at the LHC are provided, and nice agreement of our numerical results at NLO with the ALICE measurement is observed. Predictions of the yield ratios of neutral mesons such as ϕ/π0 , ϕ/η and ϕ/ρ0 at large pT in relativistic heavy-ion collisions are also presented for the first time.Dai, WeiMon, 28 Aug 2017 16:17:39 GMThttps://repo.scoap3.org/record/21283urn:ISSN:1434-6052Springer/Società Italiana di Fisica2017-8-28Quantifying jet transport properties via large pT hadron production
https://repo.scoap3.org/record/13470
Nuclear modification factor RAA for large pT single hadron is studied in a next-to-leading order perturbative QCD parton model with medium-modified fragmentation functions (mFFs) due to jet quenching in high-energy heavy-ion collisions. The energy loss of the hard partons in the quark–gluon plasma is incorporated in the mFFs which utilize two most important parameters to characterize the transport properties of the hard parton jets: the jet transport parameter q^0 and the mean free path λ0 , both at the initial time τ0 . A phenomenological study of the experimental data for RAA(pT) is performed to constrain the two parameters with simultaneous χ2/d.o.f. fits to Relativistic Heavy Ion Collider as well as Large Hadron Collider data. We obtain for energetic quarks q^0≈1.1±0.2 GeV 2 /fm and λ0≈0.4±0.03 fm in central Au+Au collisions at sNN=200 GeV, while q^0≈1.7±0.3 GeV 2 /fm, and λ0≈0.5±0.05 fm in central Pb+Pb collisions at sNN=2.76 TeV. Numerical analysis shows that the best fit favors a multiple scattering picture for the energetic jets propagating through the bulk medium, with a moderate averaged number of gluon emissions. Based on the best constraints for λ0 and τ0 , the estimated value for the mean-squared transverse momentum broadening is moderate which implies that the hard jets go through the medium with small reflection.Liu, Zhi-QuanTue, 19 Jan 2016 01:34:19 GMThttps://repo.scoap3.org/record/13470urn:ISSN:1434-6052Springer/Società Italiana di Fisica2016-1-18η meson production of high-energy nuclear collisions at NLO
https://repo.scoap3.org/record/11960
The transverse momentum spectrum of η meson in relativistic heavy-ion collisions is studied at the Next-to-Leading Order (NLO) within the perturbative QCD, where the jet quenching effect in the QGP is incorporated with the effectively medium-modified η fragmentation functions using the higher-twist approach. We show that the theoretical simulations could give nice descriptions of PHENIX data on η meson in both p+p and central Au + Au collisions at the RHIC, and also provide numerical predictions of η spectra in central Pb + Pb collisions with sNN=2.76 TeV at the LHC. The ratios of η/π0 in p+p and in central Au + Au collisions at 200 GeV are found to overlap in a wide pT region, which matches well the measured ratio η/π0 by PHENIX. We demonstrate that, at the asymptotic region when pT→∞ the ratios of η/π0 in both Au + Au and p+p are almost determined only by quark jets fragmentation and thus approach to the one in e+e− scattering; in addition, the almost identical gluon (quark) contribution fractions to η and to π result in a rather moderate variation of η/π0 distribution at intermediate and high pT region in A+A relative to that in p+p ; while a slightly higher η/π0 at small pT in Au + Au can be observed due to larger suppression of gluon contribution fraction to π0 as compared to the one to η . The theoretical prediction for η/π0 at the LHC has also been presented.Dai, WeiThu, 24 Sep 2015 15:37:29 GMThttps://repo.scoap3.org/record/11960urn:ISSN:0370-2693Elsevier2017-03-23Probing shadowed nuclear sea with massive gauge bosons in the future heavy-ion collisions
https://repo.scoap3.org/record/11819
The production of the massive bosons Z0 and W± could provide an excellent tool to study cold nuclear matter effects and the modifications of nuclear parton distribution functions (nPDFs) relative to the parton distribution functions (PDFs) of a free proton in high-energy nuclear reactions at the LHC as well as in heavy-ion collisions (HIC) with much higher center-of-mass energies available in the future colliders. In this paper we calculate the rapidity and transverse momentum distributions of the vector boson and their nuclear modification factors in p + Pb collisions at sNN=63 TeV and in Pb + Pb collisions at sNN=39 TeV in the framework of perturbative QCD by utilizing three parametrization sets of nPDFs: EPS09, DSSZ, and nCTEQ. It is found that in heavy-ion collisions at such high colliding energies, both the rapidity distribution and the transverse momentum spectrum of vector bosons are considerably suppressed in wide kinematic regions with respect to p + p reactions due to large nuclear shadowing effect. We demonstrate that the massive vector boson production processes with sea quarks in the initial state may give more contributions than those with valence quarks in the initial state; therefore in future heavy-ion collisions the isospin effect is less pronounced and the charge asymmetry of the W boson will be reduced significantly as compared to that at the LHC. A large difference between results with nCTEQ and results with EPS09 and DSSZ is observed in nuclear modifications of both rapidity and pT distributions of Z0 and W in the future HIC.Ru, PengTue, 15 Sep 2015 11:50:12 GMThttps://repo.scoap3.org/record/11819urn:ISSN:1434-6052Springer/Società Italiana di Fisica2015-9-15