S+W中心碰撞的奇异粒子产生

用相对论核－核碰撞的事例产生器──LUCIAE产生和分析了200A GeV S＋W中心碰撞中的奇异介子K0s、奇异重子A和A,给出了它们的产额对横质量的分布及奇异介子对有异重子的产生比,并与实验数据进行了比较.     

相对论性核–核碰撞中奇异夸克压低的约化

用含S夸克压低约化机制的事件产生器LUCIAE研究了相对论性核一核碰撞中青异增强现象,LUCIAE结果和相应的NA35实验数据符合得较好.结果还表明:s夸克压低约化在奇异产生物理中的作用要大于再散射.     

Comparison of source images for protons, pi-'s, and lambda's in 6A GeV Au+Au collisions

Source images are extracted from two-particle correlations constructed from strange and nonstrange hadrons produced in 6A GeV Au+Au collisions. Very different source images result from pp vs p Lambda vs pi(-)pi(-) correlations. Scaling by transverse mass can describe the apparent source size ratio for p/pi(-) but not for Lambda/pi(-) or Lambda/p. These observations suggest important differences in the space-time emission histories for protons, pions, and neutral strange baryons produced in the same events.     

Event-by-event fluctuations of the Kaon-to-Pion ratio in central Pb+Pb collisions at 158 GeV per nucleon

We present the first measurement of fluctuations from event to event in the production of strange particles in collisions of heavy nuclei. The ratio of charged kaons to charged pions is determined for individual central Pb+Pb collisions. After accounting for the fluctuations due to detector resolution and finite number statistics we derive an upper limit on genuine nonstatistical fluctuations, which could be related to a first- or second-order QCD phase transition. Such fluctuations are shown to be very small.     

A Monte Carlo Study of Lambda Hyperon Polarization at BM@N

Heavy strange objects (hyperons) can provide essential signatures of the excited and compressed baryonic matter. At NICA, it is planned to study hyperons both in the collider mode (MPD detector) and the fixed-target one (BM@N setup). Measurements of strange hyperon polarization can give additional information on the strong interaction mechanisms. In heavy-ion collisions, such measurements are even more valuable since the polarization is expected to be sensitive to characteristics of the QCD medium (vorticity, hydrodynamic helicity) and to QCD anomalous transport. In this analysis, the possibility to measure at BM@N the polarization of the lightest strange hyperon Λ is studied in Monte Carlo event samples of Au + Au collisions produced with the DCM-QGSM generator. It is shown that the detector will allow to measure polarization with a precision required to check the model predictions.     

Strange prospects for LHC energies

Strange quark and hadron production will be studied at the large hadron collider (LHC) energies in order to explore the properties of both pp and heavy-ion collisions. The ALICE experiment will be specifically efficient in the strange sector with the identification of baryons and mesons over a wide range of transverse momentum. Dedicated measurements are proposed for investigating chemical equilibration and bulk properties. Strange particles can also help to probe kinematical regions where hard processes and pQCD dominate. We try to anticipate here several ALICE analyses to be performed as the first Pb–Pb and pp data will be available. PACS 25.75.-q; 25.75.Dw     

X（1835）： A Possible Baryonium？

We point out that the large pp^- coupling of X（1835） and the suppression of the three-body strange final states strongly indicate that X（1835） may be a pp^- baryonium. We also point out that the branching ratio of X（1835） →ηππ should be bigger than that of X（1835） →η′ππ. We suggest BES search X（1835） in the ηππ channel Finally, X（1835） may be used a tetraquark generator if X（1835） is really established as a baryonium state.     

Measurement of spin-correlation parameters ANN,ASS, and ASL at 2.1 GeV in proton-proton elastic scattering

At the Cooler Synchrotron COSY/Jülich spin-correlation parameters in elastic proton-proton (pp) scattering have been measured with a 2.11 GeV polarized proton beam and a polarized hydrogen atomic beam target. We report results for A(NN), A(SS), and A(SL) for c.m. scattering angles between 30 degrees and 90 degrees. Our data on A(SS)--the first measurement of this observable above 800 MeV--clearly disagrees with predictions of available pp scattering phase-shift solutions while A(NN) and A(SL) are reproduced reasonably well. We show that in the direct reconstruction of the scattering amplitudes from the body of available pp elastic scattering data at 2.1 GeV the number of possible solutions is considerably reduced.     

How important are next-to-leading order models in predicting strange particle spectra in p+p collisions at STAR?

STAR has measured a variety of strange particle species in p+p collisions at  =200 GeV. These high statistics data are ideal for comparing to existing leading- and next-to-leading order perturbative QCD (pQCD) models. Next-to-leading (NLO) models have been successful in describing inclusive hadron production using parameterized fragmentation functions (FF) for quarks and gluons. However, in order to describe identified strange particle spectra at NLO, knowledge of flavor separated FF is essential. Such FF have recently been parameterized using data by the OPAL experiment and allow for the first time to perform NLO calculation for strange baryons. In fact, comparing the STAR Λ data with these calculations allow to put a constraint on the gluon fragmentation function. We show that the leading-order (LO) event generator PYTHIA has to be tuned significantly to reproduce the STAR identified strange particle data. In particular, it fails to describe the observed enhancement of baryon-to-meson ratio at intermediate p_T (2–6 GeV/c). In heavy-ion (HI) collisions this observable has been extensively compared with models and shows a strong dependency on collision centrality or parton density. In the HI context the observed enhancement has been explained by recent approaches in terms of parton coalescense and recombination models. PACS 25.75.Dw; 25.40.Ep; 24.10.Lx     

Mass spectrum of the strange dibaryons

We investigate the mass spectrum and the density of levels of the strange dibaryons. It is shown that the density of six-quark levels is large and can reach 1/ 20 MeV^–1 in the energy range 2.1–2.7 GeV.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 33–37, May, 1986.     

Model for describing the production of Centauro events and strangelets in heavy-ion collisions

A phenomenological model for describing the production of Centauro events in relativistic heavy-ion collisions is discussed. The model provides quantitative predictions for kinematical variables, for the baryon number, and for the masses of a Centauro fireball and of its decay products. A Centauro fireball decays predominantly into nucleons, strange hyperons, and possibly strangelets. Centauro events in Pb + Pb collisions at the LHC energy are simulated for the CASTOR detector. The signatures of these events are discussed in detail.     

Strange Nonchaotic Attractor in a Nonautonomous Oscillatory System with Nonlinear Capacity

The mathematical model of a nonautonomous dynamic system with nonlinear capacity and four-dimensional phase space is numerically investigated. The behavior of the maximum characteristic Lyapunov parameter and attractor capacity, information, and correlation dimensions attendant to variations of the external force frequency is investigated. The existence of the strange nonchaotic attractor that retains the roughness property for a wide range of variations of the system parameters is established in the phase space. Results of field experiments that confirm the correctness of numerical calculations are presented.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 89–93, March, 2005.     

Effects of inelastic (re)scattering processes s→gg and gg→s on strange hadron production in pp collisions at RHIC and LHC energies

The rapidity densities at mid-rapidity and the transverse momentum distributions for strange hadrons produced in pp collisions are analyzed using the modified PACIAE model by considering the effect of inelastic (re)scattering processes s→gg and gg→s in parton (re)scattering. The calculated results of the transverse momentum spectra of the strangeness fitting with data measured by STAR and ALICE Collaborations can be improved, especially at large transverse momentum levels. This demonstrates that the effect of inelastic (re)scattering processes of s→gg and gg→s is not negligible at RHIC and LHC energy levels.     

On polarization of strange baryons in reactions p + p↦p + Λ0 + K+ and p + p↦p + Σ0 + K+ near thresholds

Polarization properties of strange baryons produced in pp reactions, p + p↦p + Λ⁰ + K⁺ and p + p↦p + Σ⁰ + K⁺, near thresholds of the final states pΛ⁰K⁺ and pΣ⁰K⁺ are analysed relative to polarizations of colliding protons. The cross-sections for pp reactions are calculated within the effective Lagrangian approach accounting for strong pp rescattering in the initial state of colliding protons with a dominant contribution of the one-pion exchange and strong final-state interaction of daughter hadrons (Eur. Phys. J. A 9, 425 (2000)). Received: 22 October 2001 / Accepted: 14 November 2001     

Test of the Zweig selection rule in Φ production by pp collisions

Φ production is studied in pp collisions at 24 GeV/c and compared with ?^o, ω and $\text{K}{}^1$ production. The relative suppression of the Φ is in qualitative accord with its coupling to nonstrange states. No tendency is observed for the final states to contain strange particles in conjunction with the Φ.     

致密物质状态方程:中子星与奇异星

中子星结构一直是核物理、粒子物理和天体物理共同关注的热点难题,双中子星并合事件GW170817的发现更是掀起这一研究的高潮。致密物质的状态方程是决定中子星结构的关键输入量,但是到目前为止,高密度的核物质状态方程行为依然很难确定。如今国内外已有许多运行或规划的大型核实验装置和天文观测设备,有望帮助我们很快解开致密物质状态方程的谜团。本文系统地阐述了基于微观多体理论和唯象模型对脉冲星类天体状态方程的研究现状,也讨论了奇异相变和奇异物质。结合理论计算和核物理实验及天文观测数据,致密物质状态方程的研究已取得相当多进展,但是也面临不少挑战,比如从实验和观测数据提取状态方程信息时的模型依赖,中子星各部分模型的不自洽以及各种依赖热密物质复杂动力学性质的实验和观测量。随着LIGO即将再运行而发现更多双中子星甚至中子星-黑洞等并合事件,多信使天文观测可望最终揭开中子星结构之谜。The matter state inside neutron stars (NSs) is an exciting problem in nuclear physics, particle physics and astrophysics. The equation of state (EOS) of NSs plays a crucial role in the present multimessenger astronomy, especially after the event of GW170817. Thanks to accruing studies with advanced telescopes and radioactive beam facilities, the unknown EOS of supranuclear matter could soon be understood. We review the current status of the EOS for pulsar-like compact objects, that have been studied with both microscopic many-body approaches and phenomenological models. The appearance of strange baryonic matter and strange quark matter are also discussed. We compare the theoretical predictions with different data coming from both nuclear physics experiments and astrophysical observations. Despite great progresses obtained in dense nuclear matter properties, there are various challenges ahead, such as the model dependence of the constraints extracted from either experimental or observational data, the lack of a consistent and rigorous many-body treatment of all parts of the star, the dependence of many observables on the turbulent dynamics of relevant hot dense system. As LIGO is about to run again and discover more NS merger events, multimessenger observations are expected to finally unravel the mystery of NS structure.     

Hadron scattering in an additive eikonal quark model

Total and differential cross sections for p?p, pp, π^±p, K^+-p and Ψp at high energies are analysed in an additive eikonal quark model. It is shown that the exceptionally small Ψp slope contradicts the Chou-Yang model at present energies but can be accounted for by a quark-quark potential with different ranges for different pairs of quarks. This leads to smaller rms radii for hadrons than those derived from e.m. formfactors, implying that the constituent quarks have formfactors. Predictions for hadron-neutron and strange and charmed hadron-nucleon scattering are derived.     

密度依赖口袋常数下奇异物质的热力学自洽处理及其对混合星性质的影响

在MTT口袋模型的基础上采用密度依赖口袋常数,给出了奇异夸克物质的热力学关系,并用于描述奇异夸克物质及混合星内的夸克相,研究了奇异星、混合星的性质.结果表明,密度依赖口袋常数下,奇异夸克物质的压强公式中有一个附加项,而能量密度中则没有,从而保证了系统的热力学自洽性.在新的热力学关系下,奇异夸克物质的状态方程变软,相应的奇异星的引力质量和对应的半径均变小;混合星的状态方程也变软,其质量变小,而对应的半径也变小.说明经热力学自洽处理后该模型对中子星的状态方程及相应的质量-半径关系等都有显著的影响.     

奇异星的冷却

从奇异夸克物质的热力学巨势出发计算了奇异星的组份，得到电子丰度随强相互作用耦合常数或奇异物质的密度增大而减小．利用弱电统一理论，推导了奇异物质的中微子能量损失率。通过研究有薄壳的均匀奇异星和中子垦的冷却过程，得到年轻奇异星的表面温度比同年代的中子星的表面温度低得多，这可以作为区别奇异星与中子星的观测途径。 关键词：