We study the properties of $K$ and $\bar K$ mesons in nuclear matter at finite temperature from a chiral unitary approach in coupled channels which incorporates the $s$- and p-waves of the kaon-nucleon interaction. The in-medium solution accounts for Pauli blocking effects, mean-field binding on all the baryons involved, and $π$ and kaon self-energies. We calculate $K$ and $\bar K$ (off-shell) spectral functions and single particle properties. The $\bar K$ effective mass gets lowered by about -50 MeV in cold nuclear matter at saturation density and by half this reduction at T=100 MeV. The p-wave contribution to the ${\bar K}$ optical potential, due to $Λ$, $Σ$ and $Σ^*$ excitations, becomes significant for momenta larger than 200 MeV/c and reduces the attraction felt by the $\bar K$ in the nuclear medium.The $\bar K$ spectral function spreads over a wide range of energies, reflecting the melting of the $Λ(1405)$ resonance and the contribution of $YN^{-1}$ components at finite temperature. In the $KN$ sector, we find that the low-density theorem is a good approximation for the $K$ self-energy close to saturation density due to the absence of resonance-hole excitations. The $K$ potential shows a moderate repulsive behavior, whereas the quasi-particle peak is considerably broadened with increasing density and temperature. We discuss the implications for the decay of the $ϕ$ meson at SIS/GSI energies as well as in the future FAIR/GSI project.
The in-medium behavior of bottom-strange pseudoscalar mesons in hot, isospin asymmetric and dense hadronic environment is studied using a chiral effective model. The same was recently generalized to the heavy quark sector and employed to study the behavior of open-charm and open-bottom mesons. The heavy quark (anti-quark) is treated as frozen and all medium modifications of these bottom-strange mesons are due to their strange anti-quark (quark) content. We observe a pronounced dependence of their medium mass on baryonic density and strangeness content of the medium. Certain aspects of these in…
我们提出了选定的结果奇怪的和重味介子在热的和致密的核介质中的属性，强调在自洽耦合通道方法的基础上的手征拉格朗日。在奇异性部分，我们讨论了如何在FAIR条件下的光奇异矢量的增强反应性可以绑定到其主要衰变模式（例如$\bar K^*\to\bar K π$）的介质效应和矢量介子核子相互作用中的奇异重子的激发。在重味部分，我们集中在最近的测定的粲介子和底介子的输运系数的强子气体在重子化学势为零。我们评论微观输运模拟的作用，建立从重离子碰撞的理论模型和实验观测之间的联系。
The masses of the strange mesons ($K$, $K^*$ and $ϕ$) are investigated in the presence of strong magnetic fields. The changes in the masses of these mesons arise from the mixing of the pseusdoscalar and vector mesons in the presence of a magnetic field. For the charged mesons, these mass modifications are in addition to the contributions from the lowest Landau energy levels to their masses. The decay widths, $ϕ\rightarrow K\bar K$ and $K^* \rightarrow Kπ$, in the presence of the magnetic field are studied using a field theoretic model of composite hadrons with constituent quarks/antiquarks. Th…
We investigate the in-medium masses of open charm mesons ($D$($D^0$, $D^+$), $\bar{D}$($\bar{D^0}$, $D^-$), $D_s$(${D_{s}}^+$, ${D_{s}}^-$)) and charmonium states ($J/ψ$, $ψ(3686)$, $ψ(3770)$, $χ_{c0}$, $χ_{c2}$) in strongly magnetized isospin asymmetric strange hadronic matter using a chiral effective model. In the presence of the magnetic field, the number density and scalar density of charged baryons have contributions from Landau energy levels. The mass modifications of open charm mesons arise due to their interactions with nucleons, hyperons, and the scalar fields (the non-strange field $…
The properties of open strange meson $K_1^\pm$ in nuclear matter are estimated in the QCD sum rule approach. We obtain a relation between the in-medium mass and width of $K_1^-$ ($K_1^+$) in nuclear matter, and show that the upper limit of the mass shift is as large as -249 (-35) MeV. The spectral modification of the $K_1$ meson is possible to be probed by using kaon beams at J-PARC. Such measurement together with that of $K^*$ will shed light on how chiral symmetry is partially restored in nuclear matter.
We study the medium modifications of the spectral functions as well as production cross-sections of the strange vector mesons ($ϕ$, $K^*$ and $\bar {K^*}$) in isospin asymmetric strange hadronic matter. These are obtained from the in-medium masses of the open strange mesons and the decay widths $ϕ\rightarrow K\bar K$, $K^* \rightarrow Kπ$ and $\bar {K^*} \rightarrow {\bar K}π$ in the hadronic medium. The decay widths are computed using a field theoretic model of composite hadrons with quark/antiquark constituents, from the matrix element of the light quark-antiquark pair creation term of the f…
Strange meson-baryon interaction in hot and dense medium: recent progress for a road to GSI/FAIR
本文报道了在GSI/FAIR和NICA-Dubna上进行的与重离子碰撞中近阈产生有关的两体反应中奇异强子动力学的最新研究结果。特别是，$\bar K N$散射热和密集的核物质的手征单一的框架内的耦合通道进行了研究，建立在微观离壳运输方法的实施的起点。我们着重于跃迁率的计算，特别注意超子共振和同位旋效应的激发。此外，我们探讨了“非常规”的奇异介子介子和介子重子相互作用与最近的深亚阈值$ϕ$和$Ξ$生产的HADES观测。
The in-medium mass and decay width of the $ϕ$ meson in the hot asymmetric strange hadronic matter are calculated using an effective Lagrangian approach for $ϕ$ $K\bar K$ interaction. The in-medium contributions of $K \bar K$ loop to the $ϕ$ meson self-energy are computed by the medium modified kaon and antikaon mass which is evaluated using the chiral SU(3) model. To deal with the ultraviolet divergence, we regularize the loop integral of self-energy with a dipole form factor, and present the results for cut-off mass, $Λ_c$=3 GeV. In chiral model calculations, for strange matter, we find that …
Electroproduction of phi meson from proton and the strangeness in the nucleon
我们分析了$uud - s\bar s$团簇模型中阈值附近的过程$e p \to e p ϕ$，作为质子奇异度的探针。我们的考虑是基于相对论谐振子夸克模型，它考虑了强子波函数的洛伦兹收缩效应。我们发现，当奇夸克混合率仅为（3-5）%时，敲除机制与矢量介子主导模型的衍射产生相当，这与非相对论夸克模型预测的（10-20）%相当. $uud$ -和$s\bar s$ -敲除过程的横截面对质子的四动量转移平方有着性质上不同的依赖性，可以通过实验加以区分。本文还简要讨论了在5夸克集团模型中确定质子奇异含量的一种方法。
The in-medium properties of $η$ mesons are studied in hot and dense isospin asymmetric strange magnetized matter using the chiral SU(3) hadronic mean-field model. The scalar and vector density of baryons are expressed in terms of thermal distribution functions at finite temperature and magnetic field and have dependence on the scalar fields $σ$, $ζ$, and $δ$ through the effective mass of baryons and the dependence on the vector fields $ω, ρ$, and $ϕ$ through the effective chemical potential. The properties of $η$ mesons get modified in a hot and dense magnetized environment through the medium-…
In this talk we summarize our latest results on the study of three-body systems with explicit/hidden charm and with strangeness. In particular, we focus on the $K D D $ and $K D\bar D^*$ systems, where a charm $+2$, isospin $1/2$ and strangeness $+1$ state is found with a mass around 4140 MeV in the former and a $K^*$ state, with hidden charm, at a mass around 4307 MeV is obtained in the latter. Both states are predictions of our model and the experimental confirmation of them would be important to understand the properties of the strong interaction in the presence of heavy quarks.
Elliptic flow of $ϕ$ meson and strange quark collectivity at RHIC
基于多相输运（AMPT）模型，我们在布鲁克海文国家实验室（Brookhaven National Laboratory）的相对论重离子对撞机（Heavy Ion Collider）上，从重建的$K^{+}K^{-}$衰变通道中研究了$ϕ$介子的椭圆流$v_{2}$.给出了$v_{2}$对横动量$p_T$和碰撞中心度的依赖关系，并研究了$ϕ$介子在强子相中的再散射效应.结果表明，对$ϕ$介子的$v_{2}$的实验测量可以保留$ϕ$衰变前的早期碰撞信息，并且$ϕ$ $v_2$值服从组分夸克数标度，这与对其它介子和重子的测量结果一致.研究表明，$ϕ$ $v_2$主要反映了在核-核碰撞早期发展的部分子集体性，奇异和轻的上/下夸克在强子化时也发展了类似的角各向异性性质.
The present status in the field of strange mesons in nuclei and neutron stars is reviewed. In particular, the $\bar K N$ interaction, that is governed by the presence of the $Λ(1405)$, is analyzed and the formation of the $\bar K NN$ bound state is discussed. Moreover, the properties of $\bar K$ in dense nuclear matter are studied, in connection with strangeness production in nuclear collisions and kaon condensation in neutron stars.
We discuss the convergence properties of chiral expansions for the pseudoscalar and vector charmed meson masses based on the chiral SU(3) Lagrangian. Conventional expansion strategies as formulated in terms of bare meson masses are shown to suffer from poor convergence properties. This changes once the expansion is set up in terms of on-shell masses. We find a rapid convergence of the chiral expansion from vanishing quark masses up to physical values of the strange quark mass in this case. Detailed results are presented at the one-loop level for the D-meson and D^*-meson masses. It is emphasiz…
In-medium properties of the low-lying strange, charm, and bottom baryons in symmetric nuclear matter are studied in the quark-meson coupling (QMC) model. Results for the Lorentz-scalar effective masses, mean field potentials felt by the light quarks in the baryons, in-medium bag radii, and the lowest mode bag eigenvalues are presented for those calculated using the updated data. This study completes the in-medium properties of the low-lying baryons in symmetric nuclear matter in the QMC model, for the strange, charm and bottom baryons which contain one or two strange, one charm or one bottom q…
Constraining the strangeness content of the nucleon by measuring the $ϕ$ meson mass shift in nuclear matter
利用QCD求和规则和最大熵方法研究了有限密度下$ϕ$介子的行为。结果表明，核物质中$ϕ$可能的质量移动与核子的奇异含量密切相关，核子的奇异含量与奇异σ项$σ_{sN} = m_s \langle N | \overline{s}s | N \rangle$成正比.我们的结果进一步表明，根据$σ_{sN}$的值，$ϕ$介子在核物质密度下可以得到正的或负的质量移动。我们发现，这些结果仅弱依赖于潜在的修改的宽度的$ϕ$介子峰和假设的行为的四夸克凝聚在有限密度。为了检验结果的稳定性，我们考虑了对算子乘积展开展开的高阶修正，包括$α_s$修正、奇异夸克质量的高阶项和早期工作中未考虑的高扭曲项.
We apply the basis light-front quantization framework to solve for the structures of mesons with light and strange valence quarks. Our approach treats mesons as relativistic bound states with quarks confined in both the transverse direction and the light-front longitudinal direction. The spin-orbit interactions of these confined quarks are further specified by the Nambu--Jona-Lasinio model. We address the $\mathrm{U}(1)_{\mathrm{A}}$ axial anomaly by including the Kobayashi-Maskawa-'t Hooft interaction regularized by our basis. We present the structures of the pion, the kaon, the eta meson, an…
Probing the strange quark condensate by di-electrons from phi meson decays in heavy-ion collisions at SIS energies
QCD求和规则预言，在有限重子密度下，强子物质中奇异夸克凝聚体$<\bar s s>$的变化引起了$ϕ$介子衰变的双电子谱峰位的移动.在重离子碰撞中，由于强子物质的膨胀，$ϕ$峰受到膨胀火球密度区间的影响，表现为$ϕ$区双电子谱的有效展宽。出现的增宽对$<\bar s s>$的介质内变化敏感。这使得探针直接在介质中修改$<\bar s s>$通过双电子光谱在重离子碰撞在SIS能量与HADES。
We demonstrate that a nonzero strangeness contribution to the spacelike electromagnetic form factor of the nucleon is evidence for a strange-antistrange asymmetry in the nucleon's light-front wave function, thus implying different nonperturbative contributions to the strange and antistrange quark distribution functions. A recent lattice QCD calculation of the nucleon strange quark form factor predicts that the strange quark distribution is more centralized in coordinate space than the antistrange quark distribution, and thus the strange quark distribution is more spread out in light-front mome…
