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 the mass of kaons and antikaons decreases with the increase in baryonic density whereas the finite temperature causes an increase in the mass. We observed that the in-medium $ϕ$ meson mass decreases slowly with baryonic density whereas the decay width increases rapidly. The results in the present investigation support result in the literature which indicate a small downward shift in mass and a large broadening in the decay width. In the asymmetric strange hadronic matter, the study of the $ϕ$ mesons can be relevant for the compressed strange baryonic matter and experimental observables such as dilepton spectra which can result from the experiments in the future FAIR facility at GSI.
The properties of strange pseudoscalar and vectors mesons as well as strange baryon resonances in dense matter are reviewed. Some open questions on the properties of strange hadrons in medium are addressed, such as the experimental signatures of in-medium effects coming from the hadronic phase on the final observables in heavy-ion collisions for the experimental conditions at SIS, RHIC and LHC energies.
We investigate production of ϕmesons and Ξbaryons in nucleus-nucleus collisions. Reactions on strange particles acting as a catalyser are proposed to interpret the high observed ϕyields in HADES experiments as well as the energy dependence of the widths of ϕrapidity spectra in collisions at the SPS energies. It is argued that the enhancement of Ξ- yield observed by HADES is even higher than originally reported if effects of the experimental centrality trigger are taken into account. Cross sections for new hadronic processes that could produce Ξ- are reviewed.
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…
We calculate the effects of finite density of isospin asymmetric strange hadronic matter, for different strangeness fractions, on the in-medium properties of vector $\left( D^{\ast}, D_{s}^{\ast}, B^{\ast}, B_{s}^{\ast}\right)$ and axial-vector $\left( D_{1}, D_{1s}, B_{1}, B_{1s}\right)$ mesons using chiral hadronic SU(3) model and QCD sum rules. We focus on the evaluation of in-medium mass-shift and shift of decay constant of above vector and axial vector mesons. In QCD sum rule approach the properties e.g. masses and decay constants of vector and axial vector mesons are written in terms of …
We study the properties of the light vector mesons ($ρ$, $ω$ and $ϕ$) in strange hadronic matter using the QCD sum rule approach. The in-medium masses of the vector mesons are calculated from the modifications of the light quark condensates and the gluon condensates in the hadronic medium. The light quark condensates in the hadronic matter are obtained from the values of the non strange and strange scalar fields of the explicit chiral symmetry breaking term in a chiral SU(3) model. The in-medium gluon condensate is calculated through the medium modification of a scalar dilaton field, which is …
I review progress in calculating strange quark and antiquark distributions of the nucleon using the meson cloud model. This progress parallels that of the meson cloud model, which is now a useful theoretical basis for understanding symmetry breaking in nucleon parton distribution functions. I examine the breaking of symmetries involving strange quarks and antiquarks, including quark - antiquark symmetry in the sea, SU(3) flavour symmetry and SU(6) spin-flavour symmetry.
We extend our previous study on the decay behavior of $P_c$ hadronic molecules to their strange and beauty partners. While $P_c(4380)$ and $P_c(4450)$ locate just below the $\bar DΣ_c^*$ and $\bar D^*Σ_c$ thresholds, respectively, their proposed strange partners $N(1875)$ and $N(2080)$ sit just below the $KΣ^*$ and $K^*Σ$ thresholds, respectively. Using the effective Lagrangian approach as the same as for the study of $P_c$ hadronic molecular states and with the couplings determined by the $\mathrm{SU}(3)$ flavor symmetry, the decay patterns of $N(1875)$ and $N(2080)$ are obtained assuming the…
The chemical freeze-out of hadrons created in the high energy nuclear collisions is studied within the realistic version of the hadron resonance gas model. The chemical non-equilibrium of strange particles is accounted via the usual $γ_{s}$ factor which gives us an opportunity to perform a high quality fit with $χ^2/dof \simeq 63.5/55 \simeq 1.15$ of the hadronic multiplicity ratios measured from the low AGS to the highest RHIC energies. In contrast to previous findings, at low energies we observe the strangeness enhancement instead of a suppression. In addition, the performed $γ_{s}$ fit allo…
We calculate the effects of finite density and temperature of isospin asymmetric strange hadronic matter, for different strangeness fractions, on the in-medium properties of vector $\left( D^{\ast}, D_{s}^{\ast}, B^{\ast}, B_{s}^{\ast}\right)$ and axial-vector $\left( D_{1}, D_{1s}, B_{1}, B_{1s}\right)$ mesons, using chiral hadronic SU(3) model and QCD sum rules. We focus on the evaluation of in-medium mass-shift and shift in decay constant of above vector and axial-vector mesons. In QCD sum rule approach, the properties, e.g., the masses and decay constants of vector and axial-vector mesons …
We present selected results on the properties of strange and heavy-flavoured mesons in a hot and dense nuclear medium, with emphasis in selfconsistent coupled-channel approaches based on the chiral Lagrangian. In the strangeness sector, we discuss how the enhanced reactivity of light strange vectors at FAIR conditions can be tied to in-medium effects on their predominant decay modes (e.g. $\bar K^*\to\bar K π$) and to the excitation of strange baryons in vector-meson nucleon interactions. In the heavy-flavour sector, we focus on recent determinations of the transport coefficients of charmed an…
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 $…
A detailed study of nucleon parton distribution functions is performed within a radiative Next-to-Next-to Leading Order (NNLO) parton model whose low-scale input is rigidly described by wave functions which include quarks and dressing meson-cloud. The light-front Hamiltonian dynamics fixes the three-quark wave functions and the meson cloud is introduced by means of high-order Fock component in time-ordered perturbation theory in the infinite momentum frame. Non-strange as well as strange mesons-baryon fluctuations are considered ($π$, $ρ$, $ω$, $K$ and $K^*$, together with $N$, $Δ$, $Λ$ and $Σ…
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…
We report recent results on the dynamics of strange hadrons in two-body reactions relevant for near-threshold production in heavy-ion collisions at GSI/FAIR and NICA-Dubna. In particular, $\bar K N$ scattering in hot and dense nuclear matter is studied within a chiral unitary framework in coupled channels, setting up the starting point for implementations in microscopic off-shell transport approaches. We focus on the calculation of transition rates with special attention to the excitation of hyperon resonances and isospin effects. Additionally, we explore "unconventional" strangeness generatio…
We calculate the in-medium masses of the bottomonium states ($Υ(1S)$, $Υ(2S)$, $Υ(3S)$ and $Υ(4S)$) in isospin asymmetric strange hadronic matter at finite temperatures. The medium modifications of the masses arise due to the interaction of these heavy quarkonium states with the gluon condensates of QCD. The gluon condensates in the hot hadronic matter are computed from the medium modification of a scalar dilaton field within a chiral SU(3) model, introduced in the hadronic model to incorporate the broken scale invariance of QCD. There is seen to be drop in the masses of the bottomonium states…
Masses and decay constants of scalar $D_0$ and $D_{s0}$ mesons in isospin asymmetric strange hadronic matter at finite temperature are evaluated using QCD sum rules and chiral SU(3) model. In-medium light quark condensates, $\left\langle \bar{u}u\right\rangle_{ρ_{B}}$ and $\left\langle \bar{d}d\right\rangle_{ρ_{B}}$, the strange quark condensates, $\left\langle \bar{s}s\right\rangle_{ρ_{B}}$, and the gluon condensates, $\left\langle \frac{α_{s}}π {G^a}_{μν} {G^a}^{μν} \right\rangle_{ρ_{B}}$, needed in QCD sum rule calculations are evaluated using chiral SU(3) model. As an application, we calcu…
The total binding energy of compact stars is the sum of the gravitational binding energy $(BE)_g$ and the nuclear binding energy $(BE)_n$, the last being related to the microphysics of the interactions. While the first is positive (binding) both for hadronic stars and for strange quark stars, the second is large and negative for hadronic stars (anti-binding) and either small and negative (anti-binding) or positive (binding) for strange quark stars. A hadronic star can convert into a strange quark star with a larger radius because the consequent reduction of $(BE)_g$ is over-compensated by the …
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 conditions of local thermodynamic equilibrium of baryons (non-strange, strange) and mesons (strange) are presented for central Au + Au collisions at FAIR energies using the microscopic transport model UrQMD. The net particle density, longitudinal-to-transverse pressure anisotropy and inverse slope parameters of the energy spectra of non-strange and strange hadrons are calculated inside a cell in the central region within rapidity window $|y| < 1.0$ at different time steps after the collision. We observed that the strangeness content is dominated by baryons at all energies, however contribu…
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-…
We study the properties of $D$ and $\bar{D}$ mesons in hot isospin asymmetric strange hadronic matter, arising due to their interactions with the hadrons in the hyperonic medium. The interactions of $D$ and $\bar{D}$ mesons with these light hadrons are derived by generalizing the chiral SU(3) model used for the study of hyperonic matter to SU(4). We also study the mass modifications of the charmonium states $J/ψ$, $ψ(3686)$ and $ψ(3770)$ in the isospin asymmetric strange hadronic matter at finite temperatures and investigate the possibility of the decay of the charmonium states into $D\bar D$ …
We compare relativistic mean field models with their low density expansion counterparts used to mimic non-relativistic models by consistently expanding the baryonic scalar density in powers of the baryonic number density up to ${\cal O}(13/3)$, which goes two orders beyond the order considered in previous works. We show that, due to the non-trivial density dependence of the Dirac mass, the convergence of the expansion is very slow, and the validity of the non-relativistic approximation {\bf is} questionable even at subsaturation densities. In order to analyze the roles played by strangeness an…
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.
The P-wave charm-strange mesons $D_{s0}(2317)$ and $D_{s1}(2460)$ lie below the $DK$ and $D^\ast K$ threshold respectively. They are extremely narrow because their strong decays violate the isospin symmetry. We study the possible heavy molecular states composed of a pair of excited charm strange mesons. As a byproduct, we also present the numerical results for the bottonium-like analogue.
We study the properties of strange and charm mesons in hot and dense matter within a self-consistent coupled-channel approach for the experimental conditions of density and temperature expected for the CBM experiment at FAIR/GSI. The in-medium solution at finite temperature accounts for Pauli blocking effects, mean-field binding of all the baryons involved, and meson self-energies. We analyze the behaviour in this hot and dense environment of dynamically-generated baryonic resonances together with the evolution with density and temperature of the strange and open-charm meson spectral functions…
The broad non-strange meson $f_0$(500) is considered to be a non-Breit-Wigner resonance. It is generally assumed that if a resonance is broad it can hardly be described by a Breit-Wigner form. We show here that is not true neither for the broad Z boson, nor for the much narrower $Δ(1232)$, and explain why the $f_0$(500) fits with them perfectly. Key differences between them boil down to a single parameter: the angle at which we see the resonance pole from the threshold, which explains the background, the residue phase, and the difference between the pole and Breit-Wigner parameters.
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.
Heavier resonances are continually being added to the hadronic spectrum from the Particle Data Group that follow an exponentially increasing mass spectrum. However, it has been suggested that even further states predicted from Quark Models are needed in the hadronic spectrum in order to improve the agreement between the hadron resonance gas model predictions and lattice QCD data. We find that the inclusion of such states with extrapolated branching ratios slightly decreases the freezeout temperature. To eliminate ambiguities, we introduce a first principle method to extract the freeze-out temp…
The state of the art in dibaryons with strangeness is reviewed, including the K^{-}pp dibaryon which signals the onset of antikaon-nuclear binding. A new type of strange dibaryons is highlighted, where the primary binding mechanism is provided by strong p-wave pion interactions, as demonstrated by a quasibound (I=3/2,JP=2+) pion-hyperon-nucleon dibaryon calculation.
Motivated by the recent observation of the orbital excitation $B(5970)$ by CDF collaboration, we have performed a systematical study of the mass spectrum and strong decay patterns of the higher $B$ and $B_s$ mesons. Hopefully the present investigation may provide valuable clues to further experimental exploration of these intriguing excited heavy mesons.
This work considers $K^0, \bar K^0$ meson mixings and oscillations via $K^0_1, K^0_2$ meson states at strangeness violation by weak interactions in two cases - without and with taking into account $K^0_1, K^0_2$ meson decays. In the first case the oscillation theory correctly describes $K^o, \bar K^o \to K^o, \bar K^o$ transition processes. In the second case, when we take into account meson decays, the oscillation theory cannot correctly describe this process at long distances since mainly $K^o_2$ mesons remain at long distances therefore the condition for oscillations is absent. So, at long …
The mass and current coupling constant of the $D_{s2}^* (2573)$ charmed-strange meson is calculated in the framework of two-point QCD sum rule approach. Although the quantum numbers of this meson is not exactly known, its width and decay modes are consistent with $I(J^P)=0(2^+)$, which we consider to write the interpolating current used in our calculations. Replacing the light strange quark with up or down quark we also compare the results with those of $D_{2}^*$ charmed tensor meson and estimate the order of SU(3) flavor symmetry violation.
Inspired by the present experimental status of charmed-strange mesons, we perform a systematic study of the charmed-strange meson family, in which we calculate the mass spectra of the charmed-strange meson family by taking a screening effect into account in the Godfrey-Isgur model and investigate the corresponding strong decays via the quark pair creation model. These phenomenological analyses of charmed-strange mesons not only shed light on the features of the observed charmed-strange states, but also provide important information on future experimental search for the missing higher radial an…
In the present investigation, we evaluate the in-medium partial decay widths of exited states $ψ$(4040) and $Y$(4008) decaying to the pairs of non-strange pseudoscalar $D \bar{D}$ mesons, strange pseudoscalar $D_s \bar{D}_s$ mesons, non-strange vector $D^* \bar{D}^*$ meson and pseudoscalar-vector $D \bar{D}^*$ mesons using $^3P_0$ model. The in-medium effects are incorporated through the in-medium masses of daughter mesons (calculated using the chiral SU(3) model and QCD sum rule approach in our previous works). We consider $ψ$(4040) and $Y$(4008) states as 3$^3S_1$ states and observe the in-m…
