BRAHMS has measured rapidity density distributions of protons and antiprotons in both p+p and Au+Au collisions at 62 GeV and 200 GeV. From these distributions the yields of so-called "net-protons", that is the difference between the proton and antiproton yields, can be determined. The rapidity dependence of the net-proton yields from peripheral Au+Au collisions is found to have a similar behaviour to that found for the p+p results, while a quite different rapidity dependence is found for central Au+Au collisions. The net-proton distributions can be used together with model calculations to find the net-baryon yields as a function of rapidity, thus yielding information on the average rapidity loss of beam particles, the baryon transport properties of the medium, and the amount of "stopping" in these collisions.
Two Key Day-One Observables in Electron-Nucleus Collisions at the Upcoming Electron-Ion Collider and Their Implications for Baryon Number Carrier Investigations
Institute of Theoretical Physics, State Key Laboratory of Quantum Optics Technologies and Devices & Collaborative Innovation Center of Extreme Optics, Shanxi University（山西大学理论物理研究所、量子光学技术与器件国家重点实验室及极端光学协同创新中心）；Laboratory of High Energy Physics, Physical-Technical Institute of Uzbekistan Academy of Sciences（乌兹别克斯坦科学院物理技术研究所高能物理实验室）；Department of Natural Sciences, National University of Science and Technology MISIS (NUST MISIS), Almalyk Branch（国立科技大学米西思（NUST MISIS）阿尔马雷克分校自然科学系）
Multi-strange baryon elliptic flow in Au+Au collisions at sqrt(s_NN)= 200 GeV
本文报道了多奇异重子椭圆流$v_2(p_T)$的首次测量结果。多奇异重子的$Ξ+\bar{Xi}$和$Ω+\bar{Omega} in heavy-ion collisions. In minimum bias Au+Au collisions at sqrt(s_NN) = 200 GeV, a significant amount of elliptic flow, comparable to other non-strange baryons, is observed for multi-strange baryons which are expected to be particularly sensitive to the dynamics of the partonic stage of heavy-ion collisions. The $ p_T $ dependence of $ v_2$证实了以前在轻强子中观察到的组分夸克标度数。这些结果支持的想法，观察到的集体运动的相当大的一部分是在RHIC的超相对论性核碰撞的早期部分子阶段开发。
Experimental evidence for narrow baryons in the mass range 1.0$\le$ M $\le$1.46 GeV
在T $_{p}$ =2 GeV附近，研究了不同入射能量下p p $\to$ p ${π^+}X$反应.在缺失质量M $_{X}$和不变质量M $_{pπ^{+}}$中观察到了窄重子结构。这些结构的质量分别为：1004、1044、1094、1136、1173、1249、1277和1384 MeV（可能还有1339 MeV）。在d p $\to$ p p X反应的缺失质谱中，也观察到其中一些分子的质量相同，但特征较弱。进行了许多检查，以确保这些结构不是由实验工件产生的。利用已发表的光核子截面也提取了几个窄的小振幅峰。所有这些结果的小宽度，以及所观察到的结构的稳定性，无论实验如何，都被用来得出结论，它们是真正的重子，而不仅仅是动力学再散射的结果。这些重子不能与经典的$q^{3}$夸克组态相关联。我们将它们与两种色团夸克组态联系起来。
Studying baryon number transport dynamics via hyperon-kaon correlations in $p + \mathrm{Au}$ collisions at $\sqrt{s_{_{\rm NN}}}=20$, $39$ and $62$ GeV
Key Laboratory of Nuclear Physics and Ion-beam Application (MOE), Fudan University（核物理与离子束应用教育部重点实验室，复旦大学）
We investigate possible effects of correlations between stopped nucleons on higher order proton cumulants at low energy heavy-ion collisions. We find that fluctuations of the number of wounded nucleons $N_{\mathrm{part}}$ lead to rather nontrivial dependence of the correlations on the centrality; however, this effect is too small to explain the large and positive four-proton correlations found in the preliminary data collected by the STAR collaboration at $\sqrt{s}=7.7$ GeV. We further demonstrate that, by taking into account additional proton clustering, we are able to qualitatively reproduce…
We analyze the rapidity and transverse momentum dependence for the cumulants of the net-proton and net-baryon distributions in Au+Au collisions at $\sqrt{s_{\text{NN}}} = 5\,\text{GeV}$ with a microscopic hadronic transport (JAM) model. To study the effects of mean field potential and softening of equation of state (EoS) on the fluctuations of net-proton (baryon) in heavy-ion collisions, the calculations are performed with two different modes. The softening of EoS is realized in the model by implementing the attractive orbit in the two-body scattering to introduce a reduction pressure of the s…
We present a dynamical description of (anti)proton number fluctuations cumulants and correlation functions in central Au-Au collisions at $\sqrt{s_{\rm NN}} = 7.7-200$ GeV by utilizing viscous hydrodynamics simulations. The cumulants of proton and baryon number are calculated in a given momentum acceptance analytically, via an appropriately extended Cooper-Frye procedure describing particlization of an interacting hadron resonance gas. The effects of global baryon number conservation are taken into account using a generalized subensemble acceptance method. The experimental data of the STAR col…
Fluctuations of the baryon number in relativistic heavy-ion collisions are a promising observable to explore the structure of the QCD phase diagram. The cumulant ratios in heavy ion collisions at intermediate energies ($\sqrt{s_{\textrm{NN}}} < 7$ GeV) have not been studied to date. We investigate the effects of mean field potential and clustering on the cumulant ratios of baryon and proton number distributions in Au+Au collisions at beam energy of 1.23 GeV$/$nucleon as measured by the HADES Collaboration at GSI. Ultrarelativistic Quantum Molecular Dynamics (UrQMD) and the JAM model are used t…
