arXiv subjects

Amruta Mishra

Publications and source records attributed to Amruta Mishra.

At least 19 recordsLinked to original sources

arXiv2026

Diffusion and shear viscosity coefficients of hot isospin asymmetric strange hadronic matter using a chiral SU(3) model

We study the diffusion and shear viscosity coefficients of hot isospin asymmetric strange hadronic matter. The effects due to the baryon density, isospin, strangeness, and temperature on the nucleons and hyperons are studied within a chiral SU(3) model. The medium modifications of the baryons arise due to interactions with the mean scalar and vector fields within the model. The thermodynamic and transport properties are studied in the hot strange hadronic matter. The diffusion matrix associated with the multiple charges (baryon number, isospin, and strangeness), as well as the coefficient of shear viscosity, are computed from the Boltzmann equation using first-order Chapman--Enskog expansion within the relaxation time approximation. There are observed to be significant effects from the isospin asymmetry as well as the strangeness of the medium on the diffusion coefficients. The coefficient of shear viscosity, $η$ is observed to have a large enhancement in the presence of finite strangeness in the medium due to additional contributions from the hyperons. The effects due to isospin asymmetry on the shear viscosity coefficient is however observed to be marginal both in nuclear and hyperonic matter. The present study can be relevant for the experimental observables of asymmetric relativistic heavy-ion collisions, e.g., in the compressed baryonic matter (CBM) experiment at the FAIR facility at GSI as well as in the future J-PARC-HI program.

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arXiv2026

Thermodynamic and transport properties of hot asymmetric nuclear matter within a chiral SU(3) model

We investigate the thermodynamic and transport properties in hot nuclear matter accounting for the medium modifications of the nucleons within a chiral SU(3) model including effects from isospin asymmetry. Using the relaxation time approximation, the transport coefficients of the shear viscosity and thermal conductivity are studied. The shear viscosity, $η$, calculated within the chiral SU(3) model is observed to be smaller than the values calculated for free nucleon gas, whereas the thermal conductivity $κ$ is appreciably larger as compared to the free nucleon gas. The presence of isospin asymmetry in the medium leads to higher values of both the coefficients of shear viscosity ($η$) and thermal conductivity ($κ$), however, the effect is observed to be marginal for $η$. In the chiral SU(3) model, the effect of isospin asymmetry is observed to be larger for higher values of temperature. For T=150 MeV, there is observed to be a drop in the value of $κ$ as density is increased, contrary to the increase observed for the lower values of temperature, T=50 and 100 MeV. The shear viscosity coefficient to entropy density ratio $η/s$ drops with increasing baryon density that becomes more pronounced at higher temperatures in the chiral SU(3) model as compared to the case of a free nucleon gas. The present study of the thermodynamic as well as transport properties in hot nuclear matter is of relevance for relativistic heavy-ion collisions with different initial isospin asymmetry, in particular for the compressed baryonic matter experiment at the FAIR facility at GSI.

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arXiv2025

Open Heavy flavor mesons in hot asymmetric strange hadronic matter -- A QCD sum rule approach

The in-medium masses of the pseudoscalar open charm ($D$, $\bar D$, $D_s$ and $\bar {D_s}$) and open bottom ($B$, $\bar B$, $B_s$ and $\bar {B_s}$) mesons in hot asymmetric strange hadronic matter are studied within a QCD sum rule approach. These are computed using the medium modifications of the light quark condensates ($\langle{\bar{q_i}}{q_i}\rangle$, with $(q_i,i=1,2,3)\equiv(u,d,s)$), the gluon condensates and other operators in the operator product expansion upto mass dimension 5. Within a chiral SU(3) model, the quark condensates are obtained from the medium modifications of the non-strange and strange scalar-isoscalar fields ($σ$ and $ζ$), and the scalar-isovector field, $δ$, whereas, the gluon (scalar and twist-2) condensates are computed from the in-medium value of the dilaton field, $χ$, which is incorporated within the chiral model to mimic the broken scale invariance of QCD. The splittings of the masses of the $D-\bar D$ ($B-\bar B)$, as well as $D_s-\bar {D_s} (B_s-\bar {B_s})$ in the hadronic medium are due to the odd part of the spectral function. For the strange-charm (strange-bottom) mesons ($(q_i,i=3)\equiv s$), the value of $\langle {q_i}^\dagger {q_i} \rangle$ dominates over the contributions from the other operators of the odd part of the spectral function. This is observed as opposite behaviour of the particle-antiparticle mass splittings with the mass of the particle to be larger (smaller) than the antiparticle mass in nuclear (hyperonic) matter. The density and isospin asymmetry effects are observed to be the dominant medium effects which might have observable consequences on the production of charmonia and open charm mesons, and, on the production ratios, $D^+/D^-$ and $D^0/\bar {D^0}$, in asymmetric heavy ion collisions in the CBM experiment at FAIR at the future facility at GSI.

hep-ph↗

arXiv2025

Meson-nucleus bound states in quark meson coupling model

The formations of the $K(\bar{K})$, $D(\bar{D})$, and $B(\bar{B})$ meson-nucleus bound states in ${\rm{^{16}O}}$, ${\rm{^{40}Ca}}$, ${\rm{^{90}Zr}}$, ${\rm{^{197}Au}}$, and ${\rm{^{208}Pb}}$ nucleus are investigated using the quark meson coupling model. The model relies on a mean field description of non-overlapping nucleon bags bound by the self-consistent interactions of scalar ($σ$, $δ$) and vector ($ω$, $ρ$) mesons with the (anti)quarks inside the bags, which is further extended to explore the properties of nuclei. We estimate the meson-nucleus bound state energies by solving the Klein-Gordon equations with the real potentials calculated self-consistently within the model, using a coordinate space approach. The calculations are carried out for different nuclear interactions. The effects of Coulomb interaction are considered in the present study for the charged mesons. Our study indicates the formation of rather deeply bound $B$-mesic states at the very central region of the nuclei, compared to the $D$ and $K$ mesons, offering a more promising probe to explore subtle nuclear medium effects. The investigations of such bound states are of particular interest for the upcoming $\rm{\bar{P}ANDA}$ at FAIR, J-PARC-E29, and JLab experiments.

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arXiv2025

A study of bound states of $η, η^{'}, D^{0}$, $\bar{D^{0}}$, $B^{0}$, $\bar{B^{0}}$, $\bar{K^{0}}$ and $ϕ$ mesons with light and heavy nuclei within chiral SU(3) model

In the present work we explore the possibilities of the formation of bound states of neutral pseudoscalar mesons $η, η^{'}, D^{0}$, $\bar{D^{0}}, B^{0}, \bar{B^{0}}$ and $\bar{K^{0}}$ and the vector meson $ϕ$, with the nuclei $^{12}$C, $^{16}$O, $^{40}$Ca and $^{208}$Pb, calculating their binding energy and absorption decay width. To calculate the optical potentials of these mesons in different nuclei under study, we shall use the chiral SU(3) hadronic mean field model, in which the properties of nucleons in the medium are modified through the scalar isoscalar fields $σ$ and $ζ$ and the scalar-isovector field $δ$. The scalar-isovector field $δ$ account for the finite isospin asymmetry of different nuclei having asymmetry in number of protons and neutrons. The binding energy and absorption decay width of mesons are calculated for the ground state and some of possible excited states of the nuclei. In the chiral SU(3) model, the mesons $ η, D^{0}$, $\bar{D^{0}}, B^{0}, \bar{B^{0}}$ and $\bar{K^{0}}$ are observed to have significant negative mass shift upto nuclear saturation density which lead to the possibility of the bound states at least for ground states and some of excited states in case of heavy nuclei. For the pseudoscalar singlet $η^{'}$ and the vector meson $ϕ$ the mass shift obtained are found to be small and bound states are not formed. The present calculations are compared with different studies available in the field and will be useful in understanding the outcomes from different experimental facilities focusing on this area of research.

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arXiv2025

$ϕ$ meson in nuclear matter and atomic nuclei

The properties (masses and decay widths) of the $ϕ$ meson are investigated in nuclear matter from the $ϕ$ meson self-energy, using the tree-level $ϕK\bar{K}$ Lagrangian, and, incorporating in-medium masses of (anti)kaons calculated within the quark meson coupling (QMC) model. These mass shifts and decay widths are incorporated in the Breit-Wigner spectral function of the $ϕ$ meson to calculate the production cross-section of $ϕ$ in asymmetric nuclear matter. Considerable modifications to the production cross-section are observed at normal nuclear matter density, driven by the in-medium mass reduction and the increase in the decay width of $ϕ$ meson. The potential experienced by $ϕ$ meson in nuclear matter is used to study the possibility of formation of the $ϕ$ mesic bound state with atomic nuclei. We explore the potential formation of $ϕ$-mesic bound states in ${\rm{^{4}He}}$, ${\rm{^{12}C}}$, ${\rm{^{16}O}}$, ${\rm{^{40}Ca}}$, ${\rm{^{90}Zr}}$, ${\rm{^{197}Au}}$ and ${\rm{^{208}Pb}}$ nuclei by investigating their binding energies and absorption widths based on the corresponding $ϕ$-nucleus potentials. Our study shows shallow bound states with the light nuclei and deeply bound states in heavy nuclei. Among the investigated nuclei, a particularly distinct signal for a $ϕ$-mesic bound state is identified in ${\rm{^{16}O}}$, suggesting its potential experimental observability. The work provides valuable insights into $ϕ$ meson interactions in infinite nuclear matter and the potential formation of exotic $ϕ$-mesic nuclear states, offering promising probes for strongly interacting matter in the upcoming experiments at J-PARC, JLab, and ${\rm{\bar{P}}ANDA}$@FAIR physics program.

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arXiv2024

Charmonium production in hot magnetized hyperonic matter -- effects of baryonic Dirac sea and pseudoscalar-vector meson mixing

We investigate the medium modifications of the masses of pseudoscalar open charm ($D$ and $\bar D$) mesons and the charmonium state ($ψ(3770)$) in hot isospin asymmetric strange hadronic medium in the presence of an external magnetic field within a chiral effective model. The in-medium partial decay widths of $ψ(3770)$ to $D\bar D$ mesons are computed from the in-medium masses of the initial and final state mesons. These are computed using two light quark pair creation models - (I) the $^3P_0$ model and (II) a field theoretical (FT) model of composite hadrons with quark (and antiquark) constituents. The production cross-sections of $ψ(3770)$, arising from scattering of the $D$ and $\bar D$ mesons, are computed from the relativistic Breit-Wigner spectral function expressed in terms of the in-medium masses and the decay widths of the charmonium state. The effects of the magnetic field are considered due to the Dirac sea (DS) of the baryons, the mixing of the pseudoscalar and vector meson (PV mixing) and the Landau level contributions for the charged hadrons. The production cross-sections of $ψ(3770)$ arising due to scattering of $D^+D^-(D^0\bar{D}^0)$ mesons in the hot magnetized strange hadronic matter are observed to have distinct peak positions, when the magnetic field is large, due to the mass difference of the transverse and longitudinal components of $ψ(3770)$, arising from PV mixing. These can have observable consequences on the dilepton spectra and the production of the charm mesons in ultra-relativistic peripheral heavy ion collision experiments, where the produced magnetic field is huge.

hep-ph↗

arXiv2024

Heavy Quarkonium-nuclear bound states within a generalized linear sigma model

We estimate the binding energies of charmonium ($J/ψ$, $ψ(2S)$, $ψ(1D)$, $χ_{c0}$, $χ_{c1}$, $χ_{c2}$) and bottomonium ($Υ(1S)$, $Υ(2S)$, $Υ_2(1D)$, $χ_{b0}$, $χ_{b1}$, $χ_{b2}$) states bound in various nuclei (${\rm{^{4}He}}$, ${\rm{^{12}C}}$, ${\rm{^{16}O}}$, ${\rm{^{40}Ca}}$, ${\rm{^{90}Zr}}$, and ${\rm{^{208}Pb}}$) using the quarkonia-nuclei potentials obtained from their mass shifts in nuclear matter within the generalized linear sigma model. In the absence of light partons in heavy quarkonia, at the tree level, the medium modifications are driven by the gluon condensate, which is simulated within this model through a scalar dilaton field, $χ$, by introducing broken scale invariance of QCD. Our study shows that charmonium states bind more deeply with the atomic nuclei as compared to bottomonium states, providing a better probe for nuclear medium effects. Such bound states' investigations are particularly interesting for the upcoming J-PARC-E29, $\rm{\bar{P}ANDA}$@FAIR, and CEBAF@JLab experiments. The mass shifts of the heavy quarkonium states in hot isospin asymmetric nuclear matter are investigated and are observed to receive an appreciable medium modification. These medium effects are anticipated at FAIR@GSI, where such neutron-rich hot nuclear matter is expected to be produced.

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arXiv2024

Open Strange and Open Heavy Flavour mesons in Asymmetric Nuclear Matter within Quark Meson Coupling model

The in-medium properties of open strange ($K$, $\bar{K}$), open charm ($D$, $\bar{D}$), and open bottom ($B$, $\bar{B}$) mesons are investigated in asymmetric nuclear matter using Quark Meson Coupling (QMC) model. A direct coupling of scalar ($σ$, $δ$) and vector ($ω$, $ρ$) mesons to the light quarks and anti-quarks of these mesons give rise to the in-medium modification of the properties of the corresponding meson within the model. The inclusion of the $δ$ (scalar iso-vector) meson breaks the isospin symmetry for the masses of the light quark and antiquark doublets, causing mass splitting between ($u,\;d$) as well as ($\bar{d},\;\bar{u}$). Consequently, the considered mesons exhibit mass splittings within the isodoublets of $K$, $\bar{K}$, $D$, $\bar{D}$, $B$ and $\bar{B}$ mesons when embedded in asymmetric nuclear matter. In the current study, the interactions of the pseudoscalar meson with the scalar, as well as vector mesons, are considered, which lead to significant medium modifications of the excitation energies of the open strange (charm and bottom) mesons. In asymmetric nuclear matter, due to the interaction of the pseudoscalar meson with the vector iso-vector $ρ$ meson, there is a splitting in the excitation energies of the mesons within the isospin doublets. The isospin effects are seen to be large for high baryon densities. This study can have significant observable consequences, such as in the production ratios, e.g., $K^+/K^0$, $K^-/\bar {K^0}$, $D^+/D^0$, $D^-/\bar{D}^0$, $B^+/B^0$ and $B^-/\bar{B}^0$ in the upcoming heavy ion collision experiments at FAIR project at GSI, where the experiments are planned to be performed using neutron-rich beams to study the compressed baryonic matter.

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arXiv2023

Spectral properties of $ω$, $ρ$ and $A_1$ mesons in hot magnetized matter: effects of (inverse) magnetic catalysis

In-medium masses of the light vector $ω$, $ρ$ and axial-vector $A_1$ mesons are studied in the magnetized hot nuclear matter, accounting for the effects of (inverse) magnetic catalysis. The in-medium partial decay widths for the $A_1\rightarrow ρπ$ channels are studied from the in-medium masses of the initial and the final state particles, by applying a phenomenological Lagrangian to account for the $A_1ρπ$ interaction vertices. The masses are calculated within the QCD sum rule framework, with the medium effects coming through the light quark ($\sim \langle \bar{q}q \rangle$) and the scalar gluon condensates ($\sim \langle G^2 \rangle$), as well as the light four-quark condensate ($\sim \langle \bar{q}q\rangle^2 $). The condensates are calculated within the chiral $SU(3)$ model in terms of the medium modified scalar fields: isoscalar $σ$, $ζ$, isovector $δ$ and the dilaton field $χ$. The effects of magnetic fields are incorporated through the magnetized Dirac sea contribution as well as the Landau energy levels of protons. The incorporation of the magnetic field through the Dirac sea of nucleons lead to an enhancement (reduction) of the light quark condensates with magnetic field, give rise to the phenomenon of magnetic (inverse) catalysis. The effects of (inverse) magnetic catalysis at finite temperature nuclear matter are studied on the spectral functions and production cross-sections of the neutral $ρ$ and $A_1$ mesons. This may affect the production of the light vector and axial-vector mesons in the peripheral heavy-ion collision experiments, where estimated magnetic field is very large at the early stages of collisions with very high temperature.

hep-ph↗

arXiv2023

Production cross-sections and Radiative Decay widths of Heavy Quarkonia in magnetized matter

We study the production cross-sections and radiative decay widths of heavy quarkonia (charmonia and bottomonia) in magnetized nuclear matter. The production cross-sections of the $ψ(3770)$ and $Υ(4S)$, from the $D\bar D$ and $B\bar B$ scatterings respectively, are studied from the medium modifications of the masses and partial decay widths to open charm (bottom) mesons, of these heavy flavor mesons. Within a chiral effective model, the masses of the vector and pseudoscalar charmonium (bottomonium) states are calculated from the medium modification of a dilaton field, $χ$, which mimics the gluon condensates of QCD. In the presence of a magnetic field, there is mixing of the pseudoscalar (P) meson and the longitudinal component of the vector (V) meson (PV mixing), which leads to appreciable modifications of their masses. The radiative decay widths of the vector (V) heavy quarkonia to the pseudoscalar (P) mesons ($J/ψ\rightarrow η_c(1S) γ$, $ψ(2S)\rightarrow η_c(2S) γ$ and $ψ(1D)\rightarrow η_c(2S) γ$ for the charm sector and $Υ(NS)\rightarrow η_b(NS)γ$, $N$=1,2,3,4, for the bottom sector) in the magnetized asymmetric nuclear matter are also investigated in the present work. The difference in the mass of the transverse component from the longitudinal component of the vector meson, arising due to PV mixing, is observed as a double peak structure in the invariant mass spectrum of the production cross-section of $ψ(3770)$. The modifications of the production cross-sections as well as the radiative decay widths of the heavy quarkonia in the magnetized matter should have observable consequences on the production of these heavy flavour mesons resulting from ultra-relativistic peripheral heavy ion collision experiments, where the created magnetic field can be extremely large.

hep-ph↗

arXiv2023

Open Strange Mesons in (magnetized) nuclear matter

We investigate the mass modifications of open strange mesons (vector $K^*$ and axial vector $K_1$) in (magnetized) isospin asymmetric nuclear matter using quantum chromodynamics sum rule (QCDSR) approach. The in-medium decay widths of $K^*$ $\rightarrow$ $Kπ$ and $K_1$ $\rightarrow$ $K^*π$ are studied from the mass modifications of $K_1$, $K^*$ and $K$ mesons, using a light quark-antiquark pair creation model, namely the ${}^3 P_0$ model. The in-medium decay width for $K_1$ $\rightarrow$ $K^*π$ is compared with the decay widths calculated using a phenomenological Lagrangian. The effects of magnetic fields are also studied on the mass and the partial decay width of the vector $K^*$ meson decaying to $Kπ$. Within the QCD sum rule approach, the medium effects on the masses of the open strange mesons are calculated from the light quark condensates and the gluon condensates in the hadronic medium. The quark condensates are calculated from the medium modifications of the scalar fields ($σ$, $ζ$, and $δ$) in the mean field approximation within a chiral $SU(3)$ model, while the scalar gluon condensate is obtained from the medium modification of a scalar dilaton field ($χ$), which is introduced within the model to imitate the scale invariance breaking of QCD.

hep-ph↗

arXiv2023

Open bottom mesons in magnetized matter -- effects of (inverse) magnetic catalysis

In-medium masses of the pseudoscalar and vector open bottom mesons ($B$, $\bar{B}$, $B_s$ and $B^*$, $\bar{B}^*$, $B_s^*$) are studied in the magnetized nuclear matter by considering the effects of Dirac sea, within the chiral effective model. The mass modifications arise due to the interactions of the open bottom mesons with the nucleons and the scalar mesons, calculated in terms of the scalar and number densities of the nucleons and the scalar fields fluctuations. The effects of the magnetized Dirac sea lead to the considerable changes in the scalar fields with magnetic field, which are related to the light quark condensates. There is observed to be a (reduction) enhancement in the light quark condensates with magnetic field, a phenomenon called (inverse) magnetic catalysis.The contribution of the magnetic field on the Fermi sea of nucleons are taken into account through the Landau energy levels of protons and anomalous magnetic moments (AMMs) of the nucleons. The additional contribution of the lowest Landau level for the charged mesons are considered. The spin-magnetic field interaction between the longitudinal component of the vector and the pseudoscalar mesons ($B^{*||}(\bar{B}^{*||})-B (\bar{B}))$ and ($B_s^{*||}-B_s$) are studied, which lead to a level repulsion between their masses with magnetic field. Magnetic fields are observed to have significant contribution on the in-medium masses of the open bottom mesons through the Dirac sea effect as comparedto the case when this effect is not considered. In vacuum, considerable changes are obtained only due to the magnetized Dirac sea at zero and finite nucleonic AMMs.

hep-ph↗

arXiv2023

Dirac sea effects on Heavy Quarkonia decay widths in magnetized matter -- a field theoretic model of composite hadrons

We study the partial decay widths of charmonium (bottomonium) states to ${\rm D\bar D \; (B\bar B)}$ mesons in magnetized (nuclear) matter using a field theoretical model of composite hadrons with quark (and antiquark) constituents. These are computed from the mass modifications of the decaying and produced mesons within a chiral effective model, including the nucleon Dirac sea effects. The mass modifications of the open charm (bottom) mesons are calculated from their interactions with the nucleons and the scalar mesons, whereas the mass shift of the heavy quarkonium state is obtained from the medium change of a scalar dilaton field, $χ$, which mimics the gluon condensates of QCD. The Dirac sea contributions are observed to lead to a rise (drop) in the quark condensates as the magnetic field is increased, an effect called the (inverse) magnetic catalysis. These effects are observed to be significant and the anomalous magnetic moments (AMMs) of the nucleons are observed to play an important role. For $ρ_B$=0, there is observed to be magnetic catalysis (MC) without and with AMMs, whereas, for $ρ_B=ρ_0$, the inverse magnetic catalysis (IMC) is observed when the AMMs are taken into account, contrary to MC, when the AMMs are ignored. In the presence of a magnetic field, there are also mixings of spin 0 (pseudoscalar) and spin 1 (vector) states (PV mixing) which modify the masses of these mesons. The magnetic field effects on the heavy quarkonium decay widths should have observable consequences on the production the heavy flavour mesons, which are created in the early stage of ultra-relativistic peripheral heavy ion collisions, at RHIC and LHC, when the produced magnetic fields can still be extremely large.

hep-ph↗

arXiv2023

Charm mesons in magnetized nuclear matter -- effects of (inverse) magnetic catalysis

We investigate the in-medium masses of the pseudoscalar $(D,{\bar D},D_s^{\pm})$, and vector $(D^*,\bar{D}^*, D_s^{*\pm})$, open charm mesons in isospin asymmetric magnetized nuclear matter, accounting for the effects of Dirac sea. The masses are used to study the in-medium partial decay widths of $D^* \rightarrow D π$ ($\bar{D}^*\rightarrow \bar{D}π$) and $Ψ(3770) \rightarrow D \bar{D}$, using the $^3P_0$ model. The in-medium masses of the open charm mesons are calculated from their interactions with the nucleons and scalar mesons within the generalized chiral effective model, in terms of the scalar and number densities of nucleons and the scalar fields fluctuations. The effects of Landau energy levels of protons and AMMs of the nucleons are also considered in the magnetized nuclear matter. The light quark condensates are modified considerably with magnetic field, leading to (inverse) magnetic catalysis due to the magnetized Dirac sea effects. The magnetic field causes modifications to occur due to the mixing of the pseudoscalar and longitudinal component of the vector mesons, along with the lowest Landau level contribution to the ground state energy of the charged mesons as point particle correction. For the charmonium state $Ψ(3770)$, the effects of the magnetized Dirac sea are incorporated to the mass modifications through the medium modified scalar dilaton field $χ$ within the chiral model. The in-medium masses and decay widths of the open charm and charmonium mesons thus obtained should have important observable consequences in the production of the open charm mesons and charmonia in peripheral ultra-relativistic heavy ion collision experiments, where huge magnetic fields are expected to be created.

hep-ph↗

arXiv2023

QCD sum rule analysis of Heavy Quarkonium states in magnetized matter -- effects of (inverse) magnetic catalysis

The masses of the $1S$ and $1P$ states of heavy quarkonia are investigated in the magnetized, asymmetric nuclear medium, accounting for the Dirac sea effects, using a combined approach of chiral effective model and QCD sum rule method. These are calculated from the in-medium scalar and twist-2 gluon condensates, calculated within the chiral model. The gluon condensate is simulated through the scalar dilaton field, $χ$ introduced in the model through a scale-invariance breaking logarithmic potential. Considering the scalar fields to be classical, the dilaton field, $χ$, the non-strange isoscalar, $σ(\sim (\langle \bar u u\rangle +\langle \bar d d\rangle ))$, strange isoscalar, $ζ(\sim \langle \bar s s\rangle)$ and non-strange isovector, $δ(\sim (\langle\bar u u\rangle-\langle\bar d d\rangle)$) fields, are obtained by solving their coupled equations of motion, as derived from the chiral model Lagrangian. The effects of magnetic field due to the Dirac sea as well as the Landau energy levels of protons, and the non-zero anomalous magnetic moments of the nucleons are considered in the present study. In presence of an external magnetic field, there is also mixing between the longitudinal component of the vector meson and pseudoscalar meson (PV mixing) in both quarkonia sectors, leading to a rise (drop) of the masses of $J/ψ^{||}\ (η_c$) and $Υ^{||}(1S)\ (η_b$) states. These might show in the experimental observables, e.g., the dilepton spectra in the non-central, ultra-relativistic heavy ion collision experiments at RHIC and LHC, where the produced magnetic field is huge.

hep-ph↗

arXiv2023

Open Charm Mesons and Charmonium states in Magnetized Strange Hadronic Medium at Finite Temperature

We investigate the masses of the pseudoscalar ($D$($D^0$, $D^+$), $\bar{D}$($\bar{D^0}$, $D^-$) and vector open charm mesons ($D^*$($D^{*0}$, $D^{*+}$), ${\bar{D}}^*$(${\bar{D}}^{*0}$, $D^{*-}$) as well as the pseudoscalar ($η_c(1S)$, $η_c(2S)$) and the vector charmonium states ($J/ψ$, $ψ(2S)$, $ψ(1D)$) in the asymmetric hot strange hadronic medium in the presence of strong magnetic fields. In the magnetized medium, the mass modification of open charm mesons due to their interactions with baryons and the scalar fields ($σ$, $ζ$, and $δ$) are investigated in a chiral effective model. Moreover, the charged pseudoscalar meson ($D^\pm$), as well as the longitudinal component of charged vector meson ($D^{*\pm \parallel}$), experience additional positive mass modifications in the magnetic field due to Landau quantization. The effect of the modification of gluon condensates simulated by the medium change of dilaton field $χ$ on the masses of the charmonia is also calculated in the chiral effective model. At high temperatures, the magnetically induced modifications of scalar fields significantly reduce the in-medium masses of mesons. The effects of magnetically induced spin mixing between the pseudoscalar and the vector mesons are incorporated in our study. The spin mixing result in a positive mass shift for the longitudinal component of the vector mesons and a negative mass shift for the pseudoscalar mesons in the presence of the magnetic field. From the obtained in-medium mass shifts of charmonia and open charm mesons, we have also calculated the partial decay widths of $ψ(1D)$ to $D\bar{D}$, using a light quark pair creation model, namely the $^3P_0$ model. Spin mixing and strangeness fraction enhance the partial decay width at small magnetic fields.

hep-ph↗

arXiv2022

Medium modifications of Heavy Quarkonia masses in a generalized Linear Sigma Model

We study the mass shifts of the charmonium ($\bar{c}c$) states ($J/ψ$, $ψ(2S)$, $ψ(1D)$, $χ_{c0}$, $χ_{c1}$ and $χ_{c2}$) as well as the bottomonium ($\bar{b}b$) states ($Υ(1S)$, $Υ(2S)$, $Υ_2(1D)$, $χ_{b0}$, $χ_{b1}$ and $χ_{b2}$) in isospin asymmetric nuclear matter. These are investigated using a generalized linear sigma model. The broken scale invariance of QCD is incorporated in the chiral $SU(2)\times SU(2)$ Lagrangian through an effective potential involving logarithmic terms of a scalar (glueball) dilaton field $χ$. The mass shifts of the quarkonium states are obtained through the medium modifications of the dilaton field which simulates the scalar gluon condensate of QCD. We observe an appreciable mass drop in the states of heavy quarkonia under this study. The in-medium masses at finite densities thus obtained should modify the in-medium partial decay widths of heavy quarkonia to open heavy flavor mesons. These density effects can be probed in in the high energy nuclear collisions at the future facility at GSI (at Germany) and JINR (at Russia) in the experiments producing highly dense baryonic matter.

hep-ph↗