اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدEffects of resonance weak decays and hadronic re-scattering on the proton number fluctuations in Au + Au collisions at $sqrt{s_mathrm{NN}} = 5$ GeV from JAM model
143
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Proton number fluctuation is sensitive observable to search for the QCD critical point in heavy-ion collisions. In this paper, we studied rapidity acceptance dependence of the proton cumulants and correlation functions in most central Au+Au collisions at $sqrt{s_mathrm{NN}} = 5$ GeV from a microscopic hadronic transport model (JAM). At mid-rapidity, we found the effects of resonance weak decays and hadronic re-scattering on the proton cumulants and correlation functions are small, but those effects get larger when further increasing the rapidity acceptance. On the other hand, we found the baryon number conservation is a dominant background effect on the rapidity acceptance dependence of proton number fluctuations. It leads to a strong suppression of cumulants and cumulant ratios, as well as the negative proton correlation functions. We also studied those two effects on the energy dependence of cumulant ratios of net-proton distributions in most central Au+Au collisions at $sqrt{s_mathrm{NN}} = 5-200$ GeV from JAM model. This work can serve as a non-critical baseline for future QCD critical point search in heavy-ion collisions at high baryon density region.
قيم البحث
اقرأ أيضاً
We studied the effects of centrality fluctuation and deuteron formation on the cumulants ($C_n$) and correlation functions ($kappa_n$) of protons up to sixth order in most central ($b<3$ fm) Au+Au collisions at $sqrt{s_mathrm{NN}}$ = 3 GeV from a mic
roscopic transport model (JAM). The results are presented as a function of rapidity acceptance within transverse momentum $0.4<p_{T}<2 $ GeV/$c$. We compared the results obtained by centrality bin width correction (CBWC) using charged reference particle multiplicity with CBWC done using impact parameter bins. It was found that at low energies the centrality resolution for determining the collision centrality using charged particle multiplicities is not good enough to reduce the initial volume fluctuations effect for higher-order cumulant analysis. New methods need to be developed to classify events with high centrality resolution for heavy-ion collisions at low energies. Finally, we observed that the formation of deuteron will suppress the higher-order cumulants and correlation functions of protons and is found to be similar to the efficiency effect. This work can serve as a noncritical baseline for the QCD critical point search at the high baryon density region.
We present an analysis of proton number fluctuations in $sqrt{s_{NN}}$ = 2.4 GeV Au+Au collisions measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI. With the help of extensive detector simulations done with IQMD transport model
events including nuclear clusters, various nuisance effects influencing the observed proton cumulants have been investigated. Acceptance and efficiency corrections have been applied as a function of fine grained rapidity and transverse momentum bins, as well as considering local track density dependencies. Next, the effects of volume changes within particular centrality selections have been considered and beyond-leading-order corrections have been applied to the data. The efficiency and volume corrected proton number moments and cumulants Kn of orders n = 1, . . . , 4 have been obtained as a function of centrality and phase-space bin, as well as the corresponding correlators C_n . We find that the observed correlators show a power-law scaling with the mean number of protons, i.e. $C_n propto <N>^n$, indicative of mostly long-range multi-particle correlations in momentum space. We also present a comparison of our results with Au+Au collision data obtained at RHIC at similar centralities, but higher $sqrt{s_{NN}}$.
Light nuclei production is sensitive to the baryon density fluctuations and can be used to probe the QCD phase transition in relativistic heavy-ion collisions. In this work, we studied the production of proton, deuteron, triton in central Au+Au colli
sions at $sqrt{s_{mathrm{NN}}}$ = 5, 7.7, 11.5, 14.5, 19.6, 27, 39, 54.4, 62.4 and 200 GeV from a transport model (JAM). Based on the coalescence production of light nuclei, we calculated the energy dependence of rapidity density $dN/dy$ and particle ratios ($d/p$, $t/p$, and $t/d$). More importantly, the yield ratio $N_{{t}} times N_{{p}} / N_{{d}}^{2}$, which is sensitive to the neutron density fluctuations, shows a flat energy dependence and cannot describe the non-monotonic trend observed by the STAR experiment. Based on the nucleon coalescence, this work can provide constraint and reference to search for the QCD critical point and/or first order phase transition with light nuclei production in future heavy-ion collision experiments.
Global hyperon polarization, $overline{P}_mathrm{H}$, in Au+Au collisions over a large range of collision energy, $sqrt{s_mathrm{NN}}$, has recently been measured and successfully reproduced by hydrodynamic and transport models with intense fluid vor
ticity of the Quark-Gluon Plasma (QGP). While na{i}ve extrapolation of data trends suggests a large $overline{P}_mathrm{H}$ as the collision energy is reduced, the behavior of $overline{P}_mathrm{H}$ at small $sqrt{s_mathrm{NN}}<7.7$ GeV is unknown. Operating the STAR experiment in fixed-target mode, we have measured the polarization of $Lambda$ hyperons along the direction of global angular momentum in Au+Au collisions at $sqrt{s_mathrm{NN}}=3$ GeV. The observation of substantial polarization of $4.91pm0.81(rm stat.)pm0.15(rm syst.)$% in these collisions may require a reexamination of the viscosity of any fluid created in the collision, the thermalization timescale of rotational modes, and of hadronic mechanisms to produce global polarization.
Measurements of three-dimensional correlation functions of like-sign low transverse momentum kaon pairs from Au+Au collisions at top RHIC energy $sqrt s_{NN}$=200 GeV are presented. The extracted kaon source function is narrower than the pion one and
does not have the long tail along the pair transverse momentum direction. This indicates a much smaller role of long-lived resonance decays and/or of the emission duration on kaon emission. Three-dimensional Gaussian shape of the kaon source function can be adequately reproduced by Therminator simulations with resonance contributions taken into account. Comparison to pion data at the same energy reveals that the kaon Gaussian radii in the outward and sideward directions scale with the transverse mass $m_T$. In the longitudinal direction, unlike at lower SPS energies, the Gaussian radii do not seem to follow the exact $m_T$ scaling between kaons and pions.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
