The NA49 experiment at CERN SPS has acquired a huge data set of Pb+Pb events over a broad range of energy and centrality during the last several years. This high statistics data set, coupled with a state-of-the-art analysis technique, allows for the first model-independent extraction and energy scan of 3D emission sources for pion pairs at SPS energies. These 3D pion emission sources provide new insights into the nature of a long-range source previously reported by PHENIX at RHIC. The new results indicate that the pion source displays significant non-Gaussian tails in the longitudinal direction at 40 and 158 AGeV and in the outward direction at 158 AGeV.
Pion production in p+p interactions and Be+Be collisions at the CERN SPS energies
NA 49在束流动量为30 A GeV/c的固定靶测量中报告了中心Pb+Pb碰撞中解除禁闭开始的证据。这一观察激发了2009年在CERN SPS启动的NA 61/SHINE计划，该计划特别旨在通过测量质子-质子，质子-核和核-核碰撞中的强子产生来研究解除禁闭的开始特性。本文给出了在20 A-158 A GeV/c束流动量下p+p相互作用和$^7$ Be+ $^9$ Be碰撞中产生的带电π介子的谱。在相同的束流动量下，将NA 61/SHINE的计算结果与相应的NA 49的Pb+Pb中心碰撞数据进行了比较。
Results are presented for directed flow of negatively charged pions measured relative to the spectator plane in Pb+Pb collisions at the beam energy 40A GeV recorded by the NA49 experiment at CERN. The measure-ments were performed as a function of rapidity and transverse momentum in two classes of collision centrality. The projectile spectator symmetry plane is estimated using the transverse segmentation of the forward hadron calorimeters. Analysis details related to event selection and particle dentification are provided along with a description of the procedure used to apply corrections for t…
Rapidity-dependent transverse momentum spectra of negatively charged pions measured at different rapidities in proton-proton collisions at the Super Proton Synchrotron (SPS) at various energies within its Beam Energy Scan (BES) program are investigated by using one- and two-component standard distributions where the chemical potential and spin property of particles are implemented. The rapidity spectra are described by a double-Gaussian distribution. At the stage of kinetic freeze-out, the event patterns are structured by the scatter plots in the three-dimensional subspaces of velocity, moment…
Measurements of Hadron Production in Pion-Carbon Interactions with NA61/SHINE at the CERN SPS
NA 61/SHINE是在CERN超级质子同步加速器上设计的一个固定靶实验，用于研究强子-质子、强子-核和核-核相互作用。在这一过程中，我们提出了在π介子-碳生产相互作用，这是根本的重要性，以改善广泛的空气簇射建模，从而解释超高能宇宙射线测量确定强子的光谱结果。特别是，我们的测量（反）重子和$ρ^0$生产的π-碳相互作用可以有助于改善预测的μ子生产的空气簇射模拟使用强子相互作用模型。在这篇文章中，我们讨论了数据分析和结果从介子-碳碰撞记录在束流动量为158和350 GeV/c。初步频谱的$K^{\pm}$和$p$（$\bar{p}$），以及比较预测的强子相互作用模型中使用的空气簇射模拟。此外，我们目前的最终结果的生产$ρ^0$，$ω$和$K^{0*}$共振。
Onset of Deconfinement in Pb+Pb Collisions at the Cern SPS
NA 49固定靶实验研究了在CERN SPS的核-核反应中产生的高能量密度物质。在158 AGeV的中心Pb+Pb碰撞中，早期的能量密度大大超过了格点量子色动力学预言的夸克退禁闭阈值.产生的物质表现出强烈的横向和纵向流动。所产生的颗粒的产率的比率大致符合统计平衡。通过SPS范围内的能量扫描显示结构的能量依赖的π介子和K介子的产量以及横向质量分布的反斜率。这些特征表明，在中心Pb+Pb碰撞中，在30 A GeV左右开始产生退精细相。对涨落和相关性的分析还没有为QCD的临界点提供证据。
Indications for the onset of deconfinement in nucleus nucleus collisions
CERN NA 49合作组测量了20、30、40、80和158 AGeV中心Pb+Pb碰撞的强子末态。介子和K介子在中快度的平均横向质量在这个能量范围内几乎保持不变，而在较低的能量，在AGS，测量到一个陡峭的增加与光束能量。与p+p碰撞和模型计算相比，在较低的SPS能量下，观察到π介子和K介子产生的能量依赖性异常。假设在较低SPS能量下中心A+A碰撞达到的能量密度足以将热而致密的核物质转变为非精细相，则可以解释这些发现。
Indications for the onset of deconfinement in nucleus nucleus collisions
CERN NA 49合作组测量了20、30、40、80和158 AGeV中心Pb+Pb碰撞的强子末态。介子和K介子在中快度的平均横向质量在这个能量范围内几乎保持不变，而在较低的能量，在AGS，测量到一个陡峭的增加与光束能量。与p+p碰撞和模型计算相比，在较低的SPS能量下，观察到π介子和K介子产生的能量依赖性异常。这些发现可以解释，假设中心A+A碰撞在较低SPS能量下达到的能量密度足以迫使热和致密的核物质进入去精细相。
NA61/SHINE is a multipurpose fixed-target facility at the CERN Super Proton Synchrotron. The main goals of the NA61/SHINE strong interactions program are to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. To reach these goals, hadron production measurements are performed in the form of a two-dimensional scan by varying collision energy and system size. The Collaboration has recently finished data acquisition for its original program on strong interactions, accumulating broad data samples on hadron production in various systems …
NA 61/SHINE是CERN SPS的一个大接受度固定靶实验，主要研究各种粒子与核相互作用中的末态强子态。本文的主要内容是Ar+Sc和Be+Be碰撞的平均负电荷π介子多重数$\langle π^{-} \rangle$的初步结果。这些数据是最近由NA 61/SHINE合作组在广泛的束流动量范围内获得的。测量的快度分布$\frac{dn}{dy}$外推到未测量的区域，以获得总的多重数$\langle π^{-} \rangle$。本文介绍了一种利用EPOS MC模型计算平均受伤核子数$\langle W \rangle$的新方案。利用其它实验数据，讨论了不同碰撞和束流动量下的$\frac{\langle π\rangle}{\langle W \rangle}$
We present a measurement of the momentum spectra of $π^\pm$, K$^\pm$, p$^\pm$, $Λ$, $\barΛ$ and K$^{0}_{S}$ produced in interactions of negatively charged pions with carbon nuclei at beam momenta of 158 and 350 GeV/c. The total production cross sections are measured as well. The data were collected with the large-acceptance spectrometer of the fixed target experiment NA61/SHINE at the CERN SPS. The obtained double-differential $p$-$p_T$ spectra provide a unique reference data set with unprecedented precision and large phase-space coverage to tune models used for the simulation of particle prod…
First results on the interaction between the $ϕ$-meson and the nucleon ($N$) are presented based on the ($2+1$)-flavor lattice QCD simulations with nearly physical quark masses. Using the HAL QCD method, the spacetime correlation of the $N$-$ϕ$ system in the spin 3/2 channel is converted into the $N$-$ϕ$ scattering phase shift through the interaction potential. The $N$-$ϕ$ potential appears to be a combination of a short-range attractive core and a long-range attractive tail. The latter is found to be consistent with the two-pion exchange (TPE) obtained from the interaction between a color-dip…
Transverse momentum spectra of negative and positive pions produced at mid-(pseudo)rapidity in inelastic or non-single-diffractive proton-proton collisions and in central nucleus-nucleus collisions over an energy range from a few GeV to above 10 TeV are analyzed by a (two-component) blast-wave model with Boltzmann-Gibbs statistics and with Tsallis statistics respectively. The model results are in similarly well agreement with the experimental data measured by a few productive collaborations who work at the Heavy Ion Synchrotron (SIS), Super Proton Synchrotron (SPS), Relativistic Heavy Ion Coll…
