In nuclear collisions, a sizable fraction of the available energy is carried away by baryons. As the baryon number is conserved, the net-baryon $B-\bar{B}$ retains information on the energy-momentum carried by the incoming nuclei. A simple and consistent model for net-baryon production in high energy proton-proton and nucleus-nucleus collisions is presented. The basic ingredients of the model are valence string formation based on standard PDFs with QCD evolution and string fragmentation via the Schwinger mechanism. The results of the model are presented and compared with data at different centre-of-mass energies and centralities, as well as with existing models. These results show that a good description of the main features of net-baryon data is possible in the framework of a simplistic model, with the advantage of making the fundamental production mechanisms manifest.
The positive baryon-antibaryon production asymmetries that have been measured at LHC are real demonstrations of string junction dynamics in the proton-proton interactions of high energies. The topological presentation of pomeron exchange in the proton-proton collision of high energy is cylinder diagram that is covered with quark-gluon net. I assume that the process of double diffraction (DD) can be presented as a diagram of one pomeron exchange with the central loop of two pomeron cylinders, that is similar to the pomeron diagram with the handle or the pomeron torus. Taking into account that t…
Separate mass scaling of the widths of the rapidity distributions for mesons and baryons at energies available at the Facility for Antiproton and Ion research
本文研究了在不同的FAIR（Facility for Antiproton and Ion Research）能量下，UrQMD-3.3p1产生的粒子的快度分布宽度对束流快度的影响。用UrQMD产生的事例得到的快度分布宽度随束流快度的变化结果与已有的实验数据（E802、E877、E896、E917、NA 49）进行了比较。对于UrQMD和实验数据，快度分布的宽度被发现承担标度行为与束快度的所有强子。这样的标度行为被发现遵循单独的质量排序所研究的介子和重子。
Rapidity Dependence of Strange Particle Ratios in Nuclear Collisions
最近发现，在200 A GeV的硫诱导核碰撞中，所观察到的奇异强子丰度可以用一个热力学模型来解释，该模型中重子和介子分别处于相对化学平衡状态，总体奇异度略不饱和，但奇异强子通道之间按照相对化学平衡分布，奇异夸克化学势消失。我们发展了一个相对化学平衡概念的热力学表述，并说明了如何在配分函数中引入相对于绝对化学平衡的偏差，g.~整体奇异性的不饱和或介子和重子之间化学平衡的破坏。然后，我们继续测试现有的数据的假设，奇怪的夸克化学势消失无处不在，所有观察到的强子的快度分布可以解释一个共同的，快速相关的函数$μ_{\rm q}(η)$的重子化学势。本研究的目的是阐明在NA 36实验中观察到的奇异重子比的强快度依赖性。
Role of net baryon density on rapidity width of identified particles from the lowest energies available at the CERN Super Proton Synchrotron to those at the BNL Relativistic Heavy Ion Collider and at the CERN Large Hadron Collider
Unveiling QCD Criticality with Cross-Rapidity Net-Baryon Cumulants
Universität Heidelberg（海德堡大学）；GSI Helmholtzzentrum für Schwerionenforschung（GSI重离子研究中心）；Tsinghua University（清华大学）；University of California, Berkeley（加州大学伯克利分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）
We reconsider baryon stopping in relativistic heavy-ion collisions in a nonequilibrium-statistical framework. The approach combines earlier formulations based on quantum chromodynamics with a relativistic diffusion model through a suitably derived fluctuation-dissipation relation, thus allowing for a fully time-dependent theory that is consistent with QCD. We use an existing framework for relativistic stochastic processes in spacetime that are Markovian in phase space, and adapt it to derive a Fokker-Planck equation in rapidity space, which is solved numerically. The time evolution of the net-…
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 have studied the directed flow of light-flavor hadrons for Au + Au collisions at $\sqrt{S_{NN}}=$ 7.7 - 200 GeV. The initial condition is taken from a suitable Glauber model which is further evolved within the framework of relativistic hydrodynamics. Model calculations of the rapidity-odd directed flow ($v_1$) of identified light-flavor hadrons are compared with the available experimental data after suitably calibrating the initial condition to describe the rapidity dependence of charged particle multiplicity and net-proton yield. For reasonable choice of the initial condition, we are able …
The rapidity dependent directed flow of particles produced in a relativistic heavy ion collision can be generated in the hydrodynamic expansion of a tilted source. The asymmetry of the pressure leads to a build up of a directed flow of matter with respect to the collision axis. The experimentally observed ordering of the directed flow of baryons, pions and antibaryons can be described as resulting from the expansion of a baryon inhomogeneous fireball. An uneven distribution of baryons in the transverse plane leads to an asymmetry in the collective push for protons and antiprotons. Precise meas…
在核子海中夸克-反夸克和双夸克-反双夸克对的独立弦模型框架下，研究了CERN能区核-核碰撞中产生的$Λ$和$\barΛ$的快度分布.结果表明，除了由海双夸克碎裂产生的$Λ$ - $\barΛ$对外，还需要同动二次子$π+ N \to K + Λ$和$π+ \bar{N} \to K + \barΛ$的末态相互作用来重现数据。给出了对$Pb$ - $Pb$冲突的预测。
ANN model is used to estimate the multiplicity per rapidity for charged pions and kaons observed in various high-energy experiments from central Au+Au collisions with energies ranging from 2-200 GeV, and then compared to available experimental data, including RHIC-BRAHMS, and the future facilities at NICA and FAIR. We also used Landau hydrodynamical approach, which has a better describtion for the evolution of hot and dense matter produced in ultra-relativistic heavy-ion collisions. The approach is fitted to both results estimated from experiment and ANN simulation. We noticed that the Landau …
In this work we study the consequences of a longitudinal Bjorken expansion and a Hubble-like temperature cooling scenario on a 1+1D non-linear model of the diffusive dynamics of fluctuations in the net-baryon density. The equilibrium behavior of the fluctuations is fully encoded in the temperature dependence of the susceptibilities on the crossover side both in the vicinity of the assumed location of the critical point and at vanishing baryo-chemical potential in-line with lattice QCD calculations. We demonstrate the great sensitivity of the fluctuation observables on the dynamics, in particul…
