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In recent years, it has become possible to measure not only the magnitude of the electric ($G_E$) and magnetic ($G_M$) form factors of spin $\frac{1}{2}$ baryons, but also to measure the relative phases of those quantities in the timelike kinematic region. Aiming to interpret present $|G_E/G_M|$ data on hyperons of the baryon octet, as well as to predict future data, we present model calculations of that ratio for large invariant 4-momentum square $q^2$ in the timelike region ($q^2>0$). Without any further parameter fitting, we extend to the timelike region a covariant quark model previously developed to describe the kinematic spacelike region ($q^2 \le 0$) of the baryon octet form factors. The model takes into account both the effects of valence quarks and the excitations of the meson cloud which dresses the baryons. We report here that our results are in good agreement with very recent data from BESIII, within the uncertainty limits of our model. We also make new predictions which may be tested in the near future, when the range of the present measurements is expanded to the 20--50 GeV$^2$ region., Comment: 8 pages, 5 figures plus supplementary material. Correct Figure 2

We perform a detailed study of the $\Upsilon$-, $\eta_b$- and $B_c$-nucleus systems in momentum space to calculate the bound-state energies and the corresponding coordinate space radial wave functions. A comparison is made among different methods to obtain the partial wave decomposition of meson-nucleus potentials in momentum space, namely, (i) the spherical Bessel transform of the numerically obtained original potential in coordinate space, (ii) the partial wave decomposition of the Fourier transform of the Woods-Saxon approximated form for the original potential, and (iii) the spherical Bessel transform of the Woods-Saxon approximation of the numerically obtained original potential. The strong nuclear bound-state energies for the $\Upsilon$-$^{4}$He, $\Upsilon$-$^{12}$C, $\eta_b$-$^{4}$He, $\eta_b$-$^{12}$C, $B_c$-$^{4}$He (no Coulomb), and $B_c$-$^{12}$C (no Coulomb) systems and the corresponding wave functions in coordinate space are compared for the three methods. Furthermore, as an initial and realistic study, the $B_c^{\pm}$-$^{12}$C bound states are studied for the first time, with the effects of self-consistently calculated Coulomb potentials in $^{12}$C (when the $B_c^{\pm}$ mesons are absent)., Comment: 19 pages, 23 figures (69 .eps files for figures)

We study the axial-vector and the induced pseudoscalar form factors associated with the weak transitions between the octet baryon members in nuclear medium, using a covariant constituent quark model. We extend previous calculations of the axial transition form factors from the vacuum (free space) to the nuclear medium (symmetric nuclear matter). The extension of the model to the nuclear medium takes into account the modifications of the properties of hadrons in the medium (masses and coupling constants), as determined by the quark-meson coupling model. The axial-vector ($G_A$) and the induced pseudoscalar ($G_P$) form factors are evaluated for different values of the nuclear density $\rho$ in terms of the square transfer momentum $q^2= -Q^2$. We conclude that in general the $G_A$ and $G_P$ form factors are reduced in the nuclear medium. The reduction is stronger for light baryons and high densities. The medium modifications are milder for the heavier octet baryons, particularly at large $Q^2$. The calculations presented here can be used to estimate the cross sections of neutrino and antineutrino scattering with nucleus, and neutrino and antineutrino scattering with hyperons bound to a nucleus, as well as those in the cores of compact stars., Comment: 33 pages, 16 figures and 6 tables

For the first time, we estimate the in-medium mass shift of the two-flavored heavy mesons $B_c, B_c^*, B_s, B_s^*, D_s$ and $D_s^*$ in symmetric nuclear matter. The estimates are made by evaluating the lowest order one-loop self-energies. The enhanced excitations of intermediate state heavy-light mesons in symmetric nuclear matter are the origin of their negative mass shift. Our results show that the magnitude of the mass shift for the $B_c$ meson ($\bar{b} c$ or $b \bar{c}$) is larger than those of the $\eta_c (\bar{c} c)$ and $\eta_b (\bar{b} b)$, different from a naive expectation that it would be in-between of them. While, that of the $B_c^*$ shows the in-between of the $J/\psi$ and $\Upsilon$. We observe that the lighter vector meson excitation in each meson self-energy gives a dominant contribution for the corresponding meson mass shift, $B_c, B_s,$ and $D_s$., Comment: 21 pages, 19 figures (39 .eps files for figures), changes: unnecessary files removed, 1 figure corrected

We study the properties of the charged kaon in symmetric nuclear matter using a Bethe-Salpeter amplitude to model the quark-anti-quark bound state, which is well constrained by previous studies of its vacuum properties. The electromagnetic form factor, charge radius, decay constant and the light-front valence component probability are investigated in symmetric nuclear matter. In order to describe the constituent up and anti-strange quarks in nuclear matter, we adopt the ``quark-meson coupling (QMC) model", which has been widely applied to various hadronic and nuclear phenomena in the nuclear medium., Comment: 11 pages, 16 figures, revtex4 style. arXiv admin note: text overlap with arXiv:1404.5873

We study the role of the meson cloud on the electromagnetic transitions from decuplet ($B'$) to octet ($B$) baryons in terms of the squared four-momentum transfer $q^2$. In the quark model framework, the meson cloud dressing of the quark cores gives important contributions to the $\gamma^\ast N \to \Delta(1232)$ transition form factors. In the present work, we estimate the meson cloud contributions of all decuplet to octet baryon transitions ($\gamma^\ast B \to B'$ or $B' \to \gamma^\ast B$). Models that combine valence quark effects with pion and kaon cloud dressing provide a fair description of the radiative decays of decuplet to octet baryons, namely the $\Sigma^0(1385) \to \gamma \Lambda (1116)$ and $\Sigma^+(1385) \to \gamma \Sigma^+ (1193)$ decays. Previous studies indicated the relevance of the pion cloud effects on the $B^\prime \to \gamma^\ast B$ transition, but also suggested that the kaon cloud contributions may be important in the timelike region. We combine then the contributions of the bare core, estimated by a covariant quark model, with $q^2$-dependent contributions of pion and kaon clouds. We use the framework to calculate the Dalitz decay rates and the Dalitz decay widths of decuplet baryons in octet baryons with di-electrons ($B' \to e^+ e^- B$) or di-muons ($B' \to \mu^+ \mu^- B$). We conclude, based on the magnitude of our results, that most estimates of the $B' \to e^+ e^- B$ Dalitz decay widths may be tested at HADES and PANDA (GSI) in a near future. We discuss also the possibility of measuring the $\Delta (1232) \to \mu^+ \mu^- N$ and $\Sigma^0 (1385) \to \mu^+ \mu^- \Lambda (1116)$ decay widths in some facilities, based on the estimated branching ratios., Comment: Published at Phys. Rev. D. 28 pages, 8 figures, 11 tables. More compacted version. Appendix removed. Updated bibliography

$\Upsilon$ and $\eta_b$ nuclear bound state energies are calculated for various nuclei neglecting any possible effects of the widths. Essential input for the calculations, namely the medium-modified $B$ and $B^{*}$ meson masses, as well as the density distributions in nuclei, are calculated within the quark-meson coupling (QMC) model. The attractive potentials for the $\Upsilon$ and $\eta_b$ mesons in nuclei are calculated from the mass shifts of these mesons in nuclear matter in the local density approximation. These potentials originate from the in-medium enhanced $B\overline{B}$ and $BB^{*}$ loops in their respective self energy. After an extensive analysis we conclude that our results suggest that the $\Upsilon$ and $\eta_b$ mesons should form bound states with all the nuclei considered., Comment: 10 pages, 6 figures, 2 tables

Recent results for the $\eta_c$- and $J/\psi$-nucleus bound state energies for various nuclei are presented. The attractive potentials for the $\eta_c$ and $J/\psi$ mesons in the nuclear medium originate, respectively, from the in-medium enhanced $DD^{*}$ and $D\bar{D}$ loops in the $\eta_c$ and $J/\psi$ self energies. Our results suggest that the $\eta_c$ and $J/\psi$ mesons should form bound states with all the nuclei considered., Comment: Contribution to the proceedings of the 22nd Particles and Nuclei International Conference (PANIC 2021), 5 pages, 2 figures, and 1 table. arXiv admin note: text overlap with arXiv:2109.10995

The electromagnetic structure of the baryons is modified in the nuclear medium. The modifications can be inferred from the comparison between the electromagnetic form factors in medium with the respective form factor in vacuum. Of particular interest is the ratio between the electric and magnetic form factors in medium ($G_E^*/G_M^*$) and vacuum ($G_E/G_M$) of the octet baryon. The deviation of the double ratios ($G_E^*/G_M^*)/(G_E/G_M)$ from unity measures the impact of the medium modification of the electromagnetic structure in a nuclear medium. Measurements of the double ratios $(G_E^*/G_M^*)/(G_E/G_M)$ for different nuclear densities may become available in a near future using the polarization-transfer method developed at Jefferson Lab. We present estimates of the double ratios of octet baryons based on a covariant constituent quark model, which takes into account pion cloud excitations of the baryon cores,for different nuclear densities. Our results manifest different features, namely, enhancement or quenching depending on the baryon flavor content., Comment: Proceedings of conference PANIC 2021. 5 pages, 3 figures

We present results for the $\eta_c$-nucleus bound state energies for various nuclei using an effective Lagrangians approach. The attractive potentials for the $\eta_c$ in the nuclear medium originate from the medium-modified intermediate $D D^{*}$ state in the $\eta_c$ self energy, using the local density approximation. Our results suggest that the $\eta_c$ should form bound states with all the nuclei considered, Comment: Contribution to the proceedings of the 10th International Workshop on Charm Physics (CHARM 2020), 7 pages, 8 figures, and 1 table. To be published in PoS

[1]Abstract: This is a contribution for the PANIC 2021 Proceedings based on the articles, Eur. Phys. J. A 57, 259 (2021) and the accompanied article $[$arXiv:2109.08636 $[$hep-ph$]]$ (Hadron 2021 contribution). We have estimated for the first time the mass shifts of the $\Upsilon$ and $\eta_b$ mesons in symmetric nuclear matter by an SU(5) flavor symmetric effective Lagrangian approach, as well as the in-medium mass of $B^*$ meson by the quark-meson coupling (QMC) model. The attractive potentials for the $\Upsilon$- and $\eta_b$-nuclear matter are obtained, and one can expect for these mesons to form nuclear bound states. We have indeed found such nuclear bound states with $^{12}$C nucleus, where the results for the $^{12}$C nucleus bound state energies are new, and we report here for the first time. [2]Abstract: We estimate for the first time the mass shifts (scalar potentials) in symmetric nuclear matter of the $\Upsilon$ and $\eta_b$ mesons using an effective Lagrangian approach, as well as the in-medium mass of the $B^*$ meson by the quark-meson coupling model. The attractive potentials of both $\Upsilon$ and $\eta_b$ are expected to be strong enough for these mesons to be bound to the $^4$He nucleus, and we have obtained such nuclear bound state energies., Comment: [1] 5 pages, 3 figures (5 eps figure files, 1 table), contribution for the PANIC 2021 proceedings (September 5 - September 10, 2021), [2] 4 pages, 3 figures (5 eps figure files, 1 table), contribution for the HADRON 2021 proceedings (July 26 - July 31, 2021)

The electroweak properties of light and charmed D and Ds pseudoscalar mesons are investigated within a unified covariant constituent quark model. The quark-antiquark-meson vertices are assumed to have a symmetric form by the exchange of quark momenta, which is successful in describing the light pseudoscalar meson properties. The flavor decomposition of the elastic electromagnetic form factors, electromagnetic charge radii, and weak decay constants are calculated. Based on the results a discussion on the SU(3) and SU(4) symmetry breaking is made and a comparison with the pion and kaon properties to highlight the Higgs contribution to the structure of these mesons., Comment: 21 pages, 22 eps figures, latex PRD style, Sub. PRD (2021). To appear Phys. Rev. D (2021). All comments are welcome

We estimate the $\Upsilon$, $\eta_b$ and $B^*$ meson mass shifts in symmetric nuclear matter. The interest is, whether the strengths of the bottomonium-(nuclear matter) and charmonium-(nuclear matter) interactions are similar or different. This is because, each ($J/\Psi,\Upsilon$) and ($\eta_c,\eta_b$) meson group is usually assumed to have very similar properties based on the heavy charm and bottom quark masses. The estimate for the $\Upsilon$ is made using an SU(5) effective Lagrangian and the anomalous coupling one, by studying the $BB$, $BB^*$, and $B^*B^*$ meson loop contributions for the self-energy. As for the $\eta_b$, we include the $BB^*$ and $B^*B^*$ meson loop contributions in the self-energy. The in-medium masses of the $B$ and $B^*$ mesons appearing in the self-energy are calculated by the quark-meson coupling model. An analysis on the $BB$, $BB^*$, and $B^*B^*$ meson loops in the $\Upsilon$ mass shift is made by comparing with the corresponding $DD, DD^*$, and $D^*D^*$ meson loops for the $J/\Psi$ mass shift. Our prediction for the $\eta_b$ mass shift is made including only the lowest order $BB^*$ meson loop. The $\Upsilon$ mass shift, with including only the $BB$ loop, is predicted to be -16 to -22 MeV at the nuclear matter saturation density using the $\Upsilon BB$ coupling constant determined by the vector meson dominance model with the experimental data, while the $\eta_b$ mass shift is predicted to be -75 to -82 MeV with the SU(5) universal coupling constant determined by the $\Upsilon BB$ coupling constant. Our results show an appreciable difference between the bottomonium-(nuclear matter) and charmonium-(nuclear matter) interaction strengths. We also study the $\Upsilon$ and $\eta_b$ mass shifts in a heavy quark (heavy meson) symmetry limit., Comment: 19 pages, 9 figures (21 eps.files for figures), version to appear in EPJA

Effects of neutrino charge radius and magnetic moment constraints obtained from the astrophysical observations and reactor experiments, as well as in-medium modifications of the weak and electromagnetic nucleon form factors of the matter on the neutrino electroweak interaction with dense matter, are estimated. We use a relativistic mean-field model for the in-medium effective nucleon mass and quark-meson coupling model for nucleon form factors. We analyze the neutrino scattering cross section and mean free path in cold nuclear matter. We find that the increase of the cross section relative to that without neutrino form factors results in the decrease of the neutrino mean free path when neutrino form factors and the in-medium modifications of the nucleon weak and electromagnetic form factors are simultaneously considered. The quenching of the neutrino mean free path is evaluated to be about 12-58\% for the values of $\mu_\nu = 3 \times 10^{-12} \mu_B$ and $R_\nu = 3.5 \times 10^{-5}~\textrm{MeV}^{-1}$ compared with that obtained for the $\mu_\nu =0$ and $R_\nu =0$. The decrease of the neutrino mean free path is expected to decelerate the cooling of neutron stars. Each contribution of the neutrino form factors to the neutrino mean free path is discussed., Comment: 11 pages, 6 figures, Accepted for publication in Nuclear Physics A. arXiv admin note: text overlap with arXiv:1802.01749

$\eta_c$-nucleus bound state energies are calculated for various nuclei. Essential input for the calculations, namely the medium-modified $D$ and $D^{*}$ meson masses, as well as the density distributions in nuclei, are calculated within the quark-meson coupling (QMC) model. The attractive potentials for the $\eta_c$ meson in the nuclear medium originate from the in-medium enhanced $DD^{*}$ loops in the $\eta_c$ self-energy. Our results suggest that the $\eta_c$ meson should form bound states with all the nuclei considered., Comment: 8 pages, 6 figures

We give a short review of the quark-meson coupling (QMC) model, the quark-based model of finite nuclei and hadron interactions in a nuclear medium, highlighting on the relationship with the Skyrme effective nuclear forces. The model is based on a mean field description of nonoverlapping nucleon MIT bags bound by the self-consistent exchange of Lorentz-scalar-isoscalar, Lorentz-vector-isoscalar, and Lorentz-vector-isovector meson fields directly coupled to the light quarks up and down. In conventional nuclear physics the Skyrme effective forces are very popular, but, there is no satisfactory interpretation of the parameters appearing in the Skyrme forces. Comparing a many-body Hamiltonian generated by the QMC model in the zero-range limit with that of the Skyrme force, it is possible to obtain a remarkable agreement between the Skyrme force and the QMC effective interaction. Furthermore, it is shown that 3-body and higher order N-body forces are naturally included in the QMC-generated effective interaction., Comment: 8 pages, 3 figures, published in AAPPS (Association of Asia Pacific Physical Sciences) Bulletin, DECEMBER Vol. 29 No. 6, APCTP Section-2, pages 37 - 45 (2019). arXiv admin note: substantial text overlap with arXiv:1810.09260

Kaon electroweak properties in symmetric nuclear matter are studied in the Nambu--Jona-Lasinio model using the proper-time regularization. The valence quark properties in symmetric nuclear matter are calculated in the quark-meson coupling model, and they are used as inputs for studying the in-medium kaon properties in the NJL model. We evaluate the kaon decay constant, kaon-quark coupling constant, and $K^+$ electromagnetic form factor by two different approaches. Namely, by two different ways of calculating the in-medium constituent quark masses of the light quarks. We predict that, in both approaches, the kaon decay constant and kaon-quark coupling constant decrease as nuclear density increases, while the $K^+$ charge radius increases by 20-25\% at normal nuclear density., Comment: 13 pages, 9 figures

We present estimates of the hyperon elastic form factors for the baryon octet and the $\Omega^-$ baryon for large four-momentum transfer squared, $q^2$, in the timelike region ($q^2>0$). Experimentally, those form factors can be extracted from the $e^+ e^- \to B \bar B$ and $p \bar p \to B \bar B$ processes, where $B$ stands for a general baryon. Our results are based on calculations of the elastic electromagnetic form factors in the spacelike region ($Q^2 = - q^2 > 0$) within a covariant quark model. To connect the results in the spacelike region to those in the timelike region, we use asymptotic relations between the two regions which are constraints derived from analyticity and unitarity. We calculate the effective form factors $|G(q^2)|$ and compare them with the integrated cross section data $\sigma_{\rm Born} (q^2)$ from BaBar, BES III, and CLEO. The available data are at the moment restricted to $\Lambda$, $\Sigma^0$, $\Sigma^-$, $\Xi^-$, $\Xi^0$, and $\Omega^-$ as well as to $e^+ e^- \to \Lambda \bar \Sigma^0 $ and $e^+ e^- \to \Sigma^0 \bar \Lambda$ reactions. Our results provide useful reference for future experiments and seem to indicate that the present data are still in the non-perturbative QCD region, while the onset for the asymptotic constraints from analyticity and unitarity happens much before the region of the perturbative QCD falloff of the form factors., Comment: Published at Phys. Rev. D. 14 pages, 5 figures and 8 tables. Extended section III

In-medium valence-quark distributions of $\pi^+$ and $K^+$ mesons in symmetric nuclear matter are studied by combining the Nambu--Jona-Lasinio model and the quark-meson coupling model. The in-medium properties of the current quarks, which are used as inputs for studying the in-medium pion and kaon properties in the Nambu--Jona-Lasinio model, are calculated within the quark-meson coupling model. The light-quark condensates, light-quark dynamical masses, pion and kaon decay constants, and pion- and kaon-quark coupling constants are found to decrease as nuclear density increases. The obtained valence quark distributions in vacuum for both the $\pi^+$ and $K^+$ could reasonably describe the available experimental data over a wide range of Bjorken-$x$. The in-medium valence $u$-quark distribution in the $\pi^+$ at $Q^2=16~\mbox{GeV}^2$ is found to be almost unchanged compared to the in-vacuum case. However, the in-medium to in-vacuum ratios of both the valence $u$-quark and valence $s$-quark distributions of the $K^+$ meson at $Q^2=16~\mbox{GeV}^2$ increase with nuclear matter density, but show different $x$-dependence. Namely, the ratio for the valence $u$-quark distribution increases with $x$, while that for the valence $s$ quark decreases with $x$. These features are enhanced at higher density regions., Comment: 12 pages, REVTeX

The ratios of the baryon electric ($G_E$) to magnetic ($G_M$) form factors, $G_E/G_M$, can provide us with important information on the structure of baryons in vacuum as demonstrated in recent studies for the proton and neutron systems. It has been argued that the corresponding in-medium ratios, $G_E^\ast/G_M^\ast$, can also provide useful information on the electromagnetic structure of baryons in a nuclear medium. Although the ratios may not be measured directly in experiments except for the proton at present, the double ratios $(G_E^\ast/G_M^\ast)/(G_E/G_M)$ can be directly related to the polarization-transfer measurements of bound baryons. In the present work we estimate, for the first time, the double ratios $(G_E^\ast/G_M^\ast)/(G_E/G_M)$ for all the members of octet baryons in symmetric nuclear matter in the range $Q^2=0$--3 GeV$^2$, where $Q^2=- q^2$ with $q$ being the four-momentum transfer., Comment: Version published in Phys. Rev. D. The discussions are extended. 11 pages, 6 figures

$Z_c(4430)$ discovered by the Belle and confirmed by the LHCb in $\bar{B}^0\to\psi(2S)K^-\pi^+$ is generally considered to be a charged charmonium-like state that includes minimally two quarks and two antiquarks. $Z_c(4200)$ found in $\bar{B}^0\to J/\psi K^-\pi^+$ by the Belle is also a good candidate of a charged charmonium-like state. We demonstrate that kinematical singularities in triangle loop diagrams induce a resonance-like behavior that can consistently explain the properties (mass, width, and Argand plot) of $Z_c(4430)$ and $Z_c(4200)$ from the experimental analyses. The triangle diagrams include only experimentally well-established hadrons. Applying this idea to $\Lambda_b^0\to J/\psi p\pi^-$, we also identify triangle singularities that behave like $Z_c(4200)$, but no triangle diagram is available for $Z_c(4430)$. This is consistent with the LHCb's finding that their description of the $\Lambda_b^0\to J/\psi p\pi^-$ data is significantly improved by including a $Z_c(4200)$ contribution while $Z_c(4430)$ seems to hardly contribute. Even though the proposed mechanisms have uncertainty in the absolute strengths which are currently difficult to estimate, they are certainly a compelling alternative to tetraquark-based interpretations of $Z_c(4430)$ and $Z_c(4200)$., Comment: 6 pages, 5 figures; published version; one figure on the cutoff-dependence added

We investigate within a quark-meson coupling (QMC) model, the structure of the bound $\Xi^-$ hypernucleus $^{15}{\!\!\!_{\Xi^-}}$C ($^{14}$N + $\Xi^-$), which has been observed in a recent analysis of the KEK-E373 experiment. In the QMC model, light quarks in nonoverlapping nucleon and $\Xi^-$ bags interact self-consistently with isoscalar-scalar ($\sigma$), isoscalar-vector ($\omega$), and isovector-vector ($\rho$) mesons in the mean field approximation. The parameters of the model (quark-meson coupling constants and masses) are mostly fixed from the nuclear matter saturation properties. The QMC model closely reproduces the separation energies of the two $\Xi^-$ hyperon states in $^{15}{\!\!\!_{\Xi^-}}$C reported in the KEK-E373 analysis, and identifies their quantum numbers. We also make predictions for the cross sections for the production of the $^{15}{\!\!\!_{\Xi^-}}$C hypernuclear specta in the ($K^-, K^+$) reaction on a $^{15}$O target within a covariant effective Lagrangian model using the $\Xi^-$ bound state spinors obtained within the same QMC model., Comment: 17 Pages, 4 figures

We present $\Phi$- and $J/\Psi$--nuclear bound state energies and absorption widths for some selected nuclei, using potentials in the local density approximation computed from an effective Lagrangian approach combined with the quark-meson coupling model. Our results suggest that these mesons should form bound states with all the nuclei considered provided that these mesons are produced in nearly recoilless kinematics., Comment: Contribution to the Proceedings of 8th International Conference on Quarks and Nuclear Physics (QNP2018), November 13-17, 2018, Tsukuba, Japan. arXiv admin note: text overlap with arXiv:1711.09895

The structure and electroweak properties of the pion in symmetric nuclear matter are presented in the framework of the Nambu--Jona-Lasinio model. The pion is described as a bound state of a dressed quark-antiquark pair governed by the Bethe-Salpeter equation. For the in-medium current-light-quark properties we use the quark-meson coupling model, which describes successfully the properties of hadron in a nuclear medium. We found that the light-quark condensates, the pion decay constant and pion-quark coupling constant decrease with increasing nuclear matter density. We then predict the modifications of the charge radius of the charged pion in nuclear matter., Comment: 4 pages, 6 figures, accepted version for the QNP2018 proceedings, 8th International Conference on Quarks and Nuclear Physics (QNP2018), November 13-17, 2018, Tsukuba, Ibaraki, Japan

Effects of the in-medium modifications of nucleon form factors on neutrino interaction in dense matter are presented by considering both the weak and electromagnetic interactions of neutrinos with the constituents of the matter. A relativistic mean field and the quark-meson coupling models are respectively adopted for the effective nucleon mass and in-medium nucleon form factors. We calculate the cross-section of neutrino scattering as well as the neutrino mean free path. We found the cross sections of neutrino scattering in cold nuclear medium decreases when the in-medium modifications of the nucleon weak and electromagnetic form factors are taken into account.This reduction results in the enhancement of the neutrino mean free path, in particular at the baryon density of around a few times of the normal nuclear matter density., Comment: 4 pages, 2 figures, accepted for the QNP2018 proceedings, a talk given at QNP2018, 8th International Conference on Quarks and Nuclear Physics (QNP2018), November 13-17, 2018, Tsukuba, Ibaraki, Japan

In-medium properties of the low-lying baryons are studied in the quark-meson coupling (QMC) model, focusing on the $\Sigma_b$ and $\Xi_b$ baryons. It is predicted that the Lorentz-scalar effective mass of $\Sigma_b$ becomes smaller than that of $\Xi_b$ at moderate nuclear matter density, and as the density increases, namely, $m^*_{\Sigma_b} < m^*_{\Xi_b}$, although in vacuum $m_{\Sigma_b} > m_{\Xi_b}$. We also study the effects of the repulsive Lorentz-vector potentials on the excitation energies of these bottom baryons., Comment: 4 pages, 2 figures, version accepted for the QNP2018 proceedings, references updated, talk given at QNP2018, 8th International Conference on Quarks and Nuclear Physics, Nov. 13 -17, 2018, Tsukuba, Ibaraki, Japan

The charge form factor and weak decay constant of the pion as well as the pion-quark coupling constant in symmetric nuclear matter are explored in the framework of the Nambu--Jona-Lasinio model, where the pion is described as a bound state of dressed quark-antiquark pair obtained by the Bethe-Salpeter equation. For the in-medium current quark properties, we adopt the quark-meson coupling model, which describes successfully many hadron properties in a nuclear medium. The pion decay constant and the pion-quark coupling constant are found to decrease with increasing density as well as the magnitude of the light quark condensate. But the pion mass is found to be insensitive to density up to $1.25$ times the normal nuclear density. The pion charge form factor in the space-like region is also explored and is found to have a similar $Q^2$ dependence as the form factor in vacuum showing $1/Q^2$-behavior in large $Q^2$ region, where $Q^2$ is the negative of the four-momentum transfer squared. The modifications of the charge radius of the charged pion in nuclear matter are then estimated and the root-mean-square radius at the normal nuclear density is predicted to be larger than that in vacuum by about 20\%., Comment: 11 pages, REVTeX, to appear in Phys. Rev. C

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 quarks, as well as at least one light quark. Highlight is the prediction of the bottom baryon Lorentz-scalar effective masses, namely, the Lorentz-scalar effective mass of $\Sigma_b$ becomes smaller than that of $\Xi_b$ at moderate nuclear matter density, $m^*_{\Sigma_b} < m^*_{\Xi_b}$, although in vacuum $m_{\Sigma_b} > m_{\Xi_b}$. We study further the effects of the repulsive Lorentz-vector potentials on the excitation (total) energies of these bottom baryons., Comment: 14 pages, 14 eps-figures. Version accepted for Phys. Rev. D. arXiv admin note: text overlap with arXiv:1706.02688

Properties of $\rho$-meson in symmetric nuclear matter are investigated in a light-front constituent quark model (LFCQM), using the in-medium inputs calculated by the quark-meson coupling (QMC) model. The LFCQM used in this study was already applied for the studies of the electromagnetic properties of $\rho$-meson in vacuum, namely, the charge~$G_0$, magnetic~$G_1$, and quadrupole~$G_2$ form factors, electromagnetic charge radius, and electromagnetic decay constant. We predict that the electromagnetic decay constant, charge radius, and quadrupole moment are enhanced as increasing the nuclear matter density, while the magnetic moment is slightly quenched. Furthermore, we predict that the value $Q^2_{\rm zero}$, which crosses zero of the charge form factor, $G_0(Q^2_{\rm zero})=0$ ($Q^2 = -q^2 > 0$ with $q$ being the four-momentum transfer), decreases as increasing the nuclear matter density., Comment: 21 pages, 17 figures eps. New calculations and improved substantially. To appear in Phys. Lett. B (2018)

Impact of the in-medium modified nucleon weak and electromagnetic form factors on the neutrino mean free path in dense matter is studied by considering both the weak and electromagnetic interactions of neutrinos with the constituents of the matter. A relativistic mean field model and the quark-meson coupling model are respectively adopted for the in-medium effective nucleon mass and nucleon form factors. We find that the cross sections of neutrino scattering in cold nuclear medium decreases when the in-medium modification of the nucleon weak and electromagnetic form factors are taken into account. This reduction results in the enhancement of the neutrino mean free path, in particular at the baryon density of around a few times of the normal nuclear matter density. The enhancement of the neutrino mean free path is estimated to be about 10--40\% compared with the values obtained without the medium modification of the nucleon form factors, and the enhancement is expected to accelerate the cooling of neutron stars., Comment: REVTeX, 12 pages, to be published in PRD

We study the production of charmed baryons in the antiproton-proton and antiproton-nucleus interactions within a fully covariant model that is based on an effective Lagrangian approach. The baryon production proceeds via the $t$-channel $D^0$ and $D^{*0}$ meson-exchange diagrams. We have also explored the production of the charm-baryon hypernucleus $^{16}_{\Lambda_c^+}$O in the antiproton - $^{16}$O collisions. For antiproton beam momenta of interest to the ${\bar P}ANDA$ experiment, the 0$^\circ$ differential cross sections for the formation of $^{16}_{\Lambda_c^+}$O hypernuclear states with simple particle-hole configurations, have magnitudes in the range of a few $\mu$b/sr., Comment: 5 pages, 3 figures, Talk presented at the conference "Light-Cone 2017", held at Mumbai India, Sept 18 - 22, 2017. Version as printed in the Journal. arXiv admin note: text overlap with arXiv:1701.02225

Using the light-front kaon wave function based on a Bethe-Salpeter amplitude model for the quark-antiquark bound state, we study the Electromagnetic Form Factor (EMFF) of the kaon in nuclear medium within the framework of light-front field theory. The kaon model we adopt is well constrained by previous and recent studies to explain its properties in vacuum. The in-medium kaon EMFF is evaluated for the + component of the electromagnetic current, $J^+$, in the Breit frame. In order to consistently incorporate the constituent up and antistrange quarks of the kaon immersed in symmetric nuclear matter, we use the Quark-Meson Coupling (QMC) model, which has been widely applied to various hadronic and nuclear phenomena in a nuclear medium with success. We predict the in-medium modification of the kaon EMFF in symmetric nuclear matter. It is found that, after a fine tuning of the regulator mass, i.e. $m_R = 0.600$ GeV, the model is suitable to fit the available experimental data in vaccum within the theoretical uncertainties, and based on this we predict the in-medium modification of the EMFF., Comment: 5 pages, 4 figures eps. Contribuition to the Light-Cone 2017, 18-22 September, 2017, Mumbai, India. Submitted to Few-Body (2017), small changes and final version published

The mass and decay width of the $\phi$ meson in cold nuclear matter are computed in an effective Lagrangian approach, with the medium dependence of these properties obtained by evaluating kaon-antikaon loop contributions to the $\phi$ self-energy. At normal nuclear matter density, we find a downward shift of the $\phi$ mass by a few percent, while the decay width is enhanced by an order of magnitude. We also present $\phi$--nucleus bound state energies and absorption widths for some selected nuclei, using complex optical potentials obtained in the local density approximation. Our results suggest that the $\phi$ should form bound states with all the nuclei considered. However, the identification of the signal for these predicted bound states will need careful investigation because of their sizable absorption widths., Comment: To appear in the proceedings of the XVII International Conference on Hadron Spectroscopy and Structure, Hadron2017, 25-29 September 2017, Salamanca, Spain. arXiv admin note: text overlap with arXiv:1711.06358

The work presented at this workshop is divided into two parts. In the first part, the mass and decay width of the $\phi$-meson in cold nuclear matter are computed in an effective Lagrangian approach. The medium dependence of these properties are obtained by evaluating kaon-antikaon loop contributions to the $\phi$-meson self-energy, employing medium-modified kaon masses calculated using the quark-meson coupling model. The loop integral is regularized with a dipole form factor, and the sensitivity of the results to the choice of cutoff mass in the form factor is investigated. At normal nuclear matter density, we find a downward shift of the $\phi$ mass by a few percent, while the decay width is enhanced by an order of magnitude. Our results support the literature which suggest that one should observe a small downward mass shift and a large broadening of the decay width. In the second part, we present $\phi$-meson--nucleus bound state energies and absorption widths for four selected nuclei, calculated by solving the Klein-Gordon equation with complex optical potentials. The attractive potential for the $\phi$-meson in the nuclear medium originates from the in-medium enhanced KK loop in the $\phi$-meson selfenergy. The results suggest that the $\phi$-meson should form bound states with all the nuclei considered. However, the identification of the signal for these predicted bound states will need careful investigation because of their sizable absorption widths., Comment: Proceedings of the XXXI Annual Meeting of the Division of Particles and Fields of the Mexican Physical Society

We study the nucleon electromagnetic (EM) form factors in symmetric nuclear matter as well as in vacuum within a light-front approach using the in-medium inputs calculated by the quark-meson coupling model. The same in-medium quark properties are used as those used for the study of in-medium pion properties. The zero of the proton EM form factor ratio in vacuum, the electric to magnetic form factor ratio $\mu_p G_{Ep}(Q^2)/G_{Mp}(Q^2)$ ($Q^2 = -q^2 > 0$ with $q$ being the four-momentum transfer), is determined including the latest experimental data by implementing a hard constituent quark component in the nucleon wave function. A reasonable fit is achieved for the ratio $\mu_pG_{Ep}(Q^2)/G_{Mp}(Q^2)$ in vacuum, and we predict that the $Q_0^2$ value to cross the zero of the ratio to be about 15 GeV$^2$. In addition the double ratio data of the proton EM form factors in $^4$He and H nuclei, $[G^{^4{\rm He}}_{Ep}(Q^2)/G^{^4{\rm He}}_{Mp}(Q^2)]/[G^{^1{\rm H}}_{Ep}(Q^2)/G^{^1{\rm H}}_{Mp}(Q^2)]$, extracted by the polarized ($\vec{e}, e' \vec{p}$) scattering experiment on $^4$He at JLab, are well described. We also predict that the $Q_0^2$ value satisfying $\mu_pG_{Ep}(Q_0^2)/G_{Mp}(Q_0^2) = 0$ in symmetric nuclear matter, shifts to a smaller value as increasing nuclear matter density, which reflects the facts that the faster falloff of $G_{Ep}(Q^2)$ as increasing $Q^2$ and the increase of the proton mean-square charge radius. Furthermore, we calculate the neutron EM form factor double ratio in symmetric nuclear matter for $0.1 < Q^2 < 1.0$ GeV$^2$. The result shows that the neutron double ratio is enhanced relative to that in vacuum, while for the proton it is quenched, and agrees with an existing theoretical prediction., Comment: 39 pages, 11 figures. Revtex style. Title change, and news results added. To appear Nuclear Physics A

In our quest to win a deeper understanding of how QCD actually works, the study of the binding of heavy quarkonia and heavy-flavor hadrons to atomic nuclei offers enormous promise. Modern experimental facilities such as FAIR, Jefferson Lab at 12 GeV and J-PARC offer exciting new experimental opportunities to study such systems. These experimental advances are complemented by new theoretical approaches and predictions, which will both guide these experimental efforts and be informed and improved by them. This review will outline the main theoretical approaches, beginning with QCD itself, summarize recent theoretical predictions and relate them both to past experiments and those from which we may expect results in the near future.

$\phi$-meson--nucleus bound state energies and absorption widths are calculated for seven selected nuclei by solving the Klein-Gordon equation with complex optical potentials. Essential input for the calculations, namely the medium-modified $K$ and $\overline{K}$ meson masses, as well as the density distributions in nuclei, are obtained from the quark-meson coupling model. The attractive potential for the $\phi$-meson in the nuclear medium originates from the in-medium enhanced $K\overline{K}$ loop in the $\phi$-meson self-energy. The results suggest that the $\phi$-meson should form bound states with all the nuclei considered. However, the identification of the signal for these predicted bound states will need careful investigation because of their sizable absorption widths., Comment: To appear in Physical Review C; 8 pages, 5 figures. arXiv admin note: text overlap with arXiv:1706.02688

The mass and decay width of the $\phi$ meson in cold nuclear matter are computed in an effective Lagrangian approach. The medium dependence of these properties are obtained by evaluating kaon-antikaon loop contributions to the $\phi$ self-energy, employing the medium-modified kaon masses, calculated using the quark-meson coupling model. The loop integral is regularized with a dipole form factor, and the sensitivity of the results to the choice of cutoff mass in the form factor is investigated. At normal nuclear matter density we find a downward shift of the $\phi$ mass by a few percent, while the decay width is enhanced by an order of magnitude. For a large variation of the cutoff mass parameter, the results for the $\phi$ mass and the decay width turn out to vary very little. Our results support results in the literature which suggest that one should observe a small downward mass shift and a large broadening of the decay width. In order to explore the possibility of studying the binding and absorption of $\phi$ mesons in nuclei, we also present the single-particle binding energies and half-widths of $\phi$-nucleus bound states for some selected nuclei., Comment: To appear in Physics Letters B; 8 pages, 4 figures

We investigate the production of charm-baryon hypernucleus $^{16}_{\Lambda_c^+}$O in the antiproton - $^{16}$O collisions within a fully covariant model that is based on an effective Lagrangian approach. The explicit ${\bar \Lambda}_c^ - \Lambda_c^+$ production vertex is described by the $t$-channel $D^0$ and $D^{*0}$ meson-exchanges in the initial collision of the incident antiproton with one of the protons of the target nucleus. The $\Lambda_c^+$ bound state spinors as well as the self-energies of the exchanged mesons employed in our calculations are derived from the quark-meson coupling model. The parameters of various vertices are taken to be the same as those used in our previous study of the elementary ${\bar p} + p \to {\bar \Lambda}_c^- + \Lambda_c^+$ reaction. We find that for antiproton beam momenta of interest to the ${\bar P}ANDA$ experiment, the 0$^\circ$ differential cross sections for the formation of $^{16}_{\Lambda_c^+}$O hypernuclear states with simple particle-hole configurations, have magnitudes in the range of a few $\mu$b/sr., Comment: 17 pages, 5 figures, Journal print version

We give a pedagogical introduction of the stochastic variational method by considering the quantization of a non-inertial particle system. We show that the effects of fictitious forces are represented in the forms of vector fields which behave analogous to the gauge fields in the electromagnetic interaction. We further discuss that the operator expressions for observables can be defined by applying the stochastic Noether theorem., Comment: 6 pages, no figure, the proceedings of 31st International Colloquium on Group Theoretical Methods in Physics

Properties of \r{ho}-meson in symmetric nuclear matter are investigated within a light-front constituent quark model (LFCQM), using the in-medium input calculated by the quark-meson coupling (QMC) model. The LFCQM used here was previously applied in vacuum to calculate the \r{ho}-meson electromagnetic properties, namely, charge G 0 , magnetic G 1 , and quadrupole G 2 form factors, as well as the electromagnetic radius and decay constant. We predict the in-medium modifications of the \r{ho}-meson electromagnetic form factors in symmetric nuclear matter., Comment: 8 Pages, 6 eps figures. Proceedings of Light-Cone 2016, Lisbon Portugal

After a brief review of the quark-based model for nuclear matter, and some pion properties in medium presented in our previous works, we report new results for the pion valence wave function as well as the valence distribution amplitude in medium, which are presented in our recent article. We find that both the in-medium pion valence distribution and the in-medium pion valence wave function, are substantially modified at normal nuclear matter density, due to the reduction in the pion decay constant., Comment: 9 pages, 10 figures, one paragraph added, typos corrected, to be published in the proceedings of "Light Cone 2016", September 5-8, 2016, Lisbon, Portugal

We study the $\bar D D$ (${\bar D}^0 D^0$ and $D^-D^+$) charm meson pair production in antiproton (${\bar p}$) induced reactions on nuclei at beam energies ranging from threshold to several GeV. Our model is based on an effective Lagrangian approach that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The reaction proceeds via the $t$-channel exchanges of $\Lambda_c^+$, $\Sigma_c^+$, and $\Sigma_c^{++}$ baryons in the initial collision of the antiproton with one of the protons of the target nucleus. The medium effects on the exchanged baryons are included by incorporating in the corresponding propagators, the effective charm baryon masses calculated within a quark-meson coupling (QMC) model. The wave functions of the bound proton have been determined within the QMC model as well as in a phenomenological model where they are obtained by solving the Dirac equation with appropriate scalar and vector potentials. The initial- and final-state distortion effects have been approximated by using an eikonal approximation-based procedure. Detailed numerical results are presented for total and double differential cross sections for the ${\bar D}^0 D^0$ and $D^-D^+$ production reactions on $^{16}$O and $^{90}$Zr targets. It is noticed that at ${\bar p}$ beam momenta of interest to the ${\bar P}ANDA$ experiment, medium effects lead to noticeable enhancements in the charm meson production cross sections., Comment: 23 pages, 8 figures, Journal print version

We study the effect of a hot and dense medium on the binding energy of hadronic molecules with open-charm mesons. We focus on a recent chiral quark-model-based prediction of a molecular state in the $N \bar D$ system. We analyze how the two-body thresholds and the hadron-hadron interactions are modified when quark and meson masses and quark-meson couplings change in a function of the temperature and baryon density according to predictions of the Nambu--Jona-Lasinio model. We find that in some cases the molecular binding is enhanced in medium as compared to their free-space binding. We discuss the consequences of our findings for the search for exotic hadrons in high-energy heavy-ion collisions as well as in the forthcoming facilities FAIR or J-PARC., Comment: Corrected one author name

Pion valence distributions in nuclear medium and vacuum are studied in a light-front constituent quark model. The in-medium input for studying the pion properties is calculated by the quark-meson coupling model. We find that the in-medium pion valence distribution, as well as the in-medium pion valence wave function, are substantially modified at normal nuclear matter density, due to the reduction in the pion decay constant., Comment: 16 pages. 10 eps figures, typos corrected. Version to appear Physics Letters B

We study the weak interaction axial form factors of the octet baryons, within the covariant spectator quark model, focusing on the dependence of four-momentum transfer squared, Q^2. In our model the axial form factors G_A(Q^2) (axial-vector form factor) and G_P(Q^2) (induced pseudoscalar form factor), are calculated based on the constituent quark axial form factors and the octet baryon wave functions. The quark axial current is parametrized by the two constituent quark form factors, the axial-vector form factor g_A^q(Q^2), and the induced pseudoscalar form factor g_P^q(Q^2). The baryon wave functions are composed of a dominant S-state and a P-state mixture for the relative angular momentum of the quarks. First, we study in detail the nucleon case. We assume that the quark axial-vector form factor g_A^q(Q^2) has the same function form as that of the quark electromagnetic isovector form factor. The remaining parameters of the model, the P-state mixture and the Q^2-dependence of g_P^q(Q^2), are determined by a fit to the nucleon axial form factor data obtained by lattice QCD simulations with large pion masses. In this lattice QCD regime the meson cloud effects are small, and the physics associated with the valence quarks can be better calibrated. Once the valence quark model is calibrated, we extend the model to the physical regime, and use the low Q^2 experimental data to estimate the meson cloud contributions for G_A(Q^2) and G_P(Q^2). Using the calibrated quark axial form factors, and the generalization of the nucleon wave function for the other octet baryon members, we make predictions for all the possible weak interaction axial form factors G_A(Q^2) and G_P(Q^2) of the octet baryons. The results are compared with the corresponding experimental data for G_A(0), and with the estimates of baryon-meson models based on SU(6) symmetry., Comment: To appear in PRD. 32 pages, 13 figures and 11 tables

We calculate Coulomb breakup of the neutron rich nucleus $^{37}$Mg on a Pb target at the beam energy of 244 MeV/nucleon within the framework of a finite range distorted wave Born approximation theory that is extended to include the effects of projectile deformation. In this theory, the breakup amplitude involves the full wave function of the projectile ground state. Calculations have been carried out for the total one-neutron removal cross section $(\sigma_{-1n})$, the neutron-core relative energy spectrum, the parallel momentum distribution of the core fragment, the valence neutron angular, and energy-angular distributions. The calculated $\sigma_{-1n}$ has been compared with the recently measured data to put constraints on the spin parity, and the one-neutron separation energy ($S_n$) of the $^{37}$Mg ground state ($^{37}$Mg$_{gs}$). The dependence of $\sigma_{-1n}$ on the deformation of this state has also been investigated. While a spin parity assignment of $7/2^-$ for the $^{37}$Mg$_{gs}$ is ruled out by our study, neither of the $3/2^-$ and $1/2^+$ assignments can be clearly excluded. Using the spectroscopic factor of one for both the $3/2^-$ and $1/2^+$ configurations and ignoring the projectile deformation effects, the $S_n$ values of $0.35 \pm 0.06$ MeV and $0.50 \pm 0.07$ MeV, respectively, are extracted for the two configurations. However, the extracted $S_n$ is strongly dependent on the spectroscopic factor and the deformation effects of the respective configuration. The narrow parallel momentum distribution of the core fragment and the strong forward peaking of the valence neutron angular distribution suggest a one-neutron halo configuration in either of the $2p_{3/2}$ and $2s_{1/2}$ configurations of the $^{37}$Mg ground state., Comment: 11 figures, 32 pages, version to be published in Nucl. Phys. A