arXiv subjects

G. N. Zeminiani

Publications and source records attributed to G. N. Zeminiani.

10 recordsLinked to original sources

arXiv2025

In-medium mass shifts of $B_c^{()}, B_s^{()}$ and $D_s^{(*)}$ mesons

We present our predictions for the Lorentz scalar mass shifts of two-flavored heavy mesons, $B_c^{(*)}, B_s^{(*)}$ and $D_s^{(*)}$ in symmetric nuclear matter. The in-medium mass shifts are estimated by evaluating the lowest order one-loop self-energies of the mesons based on a flavor-SU(5) effective Lagrangian approach. In-medium properties necessary for the estimates are calculated by the quark-meson coupling (QMC) model. The enhanced self-energies of the mesons in symmetric nuclear matter relative to those in free space, yield the negative mass shifts of these mesons.

hep-ph↗

arXiv2025

Two-flavored heavy mesons' nuclear bound states

We calculate the $B_c$- and $B_s$-nucleus bound state energies and coordinate space radial wave functions by solving the Klein-Gordon equation in momentum space. The attractive strong potentials for the $B_c$ and $B_s$ mesons in nuclei are calculated from the respective mass shifts of these mesons in nuclear matter using a local density approximation. This negative mass shift may be regarded as a signature of partial restoration of chiral symmetry in medium in an empirical sense, because the origin of the negative mass shift in the present study is not directly related to the chiral symmetry mechanism.

nucl-th↗

arXiv2025

Two-flavored heavy-light mesons' nuclear bound states

We calculate the $B^-$-, $\overline{B^0}$-, $D^+$-, $D^0$-, $K^-$-, and $\overline{K^0}$-$^{12}$C bound state energies by solving the Klein-Gordon (K;G.) equation in momentum space, and also obtain the corresponding coordinate space radial wave functions. The strong Lorentz scalar and vector potentials in $^{12}$C are calculated using a local density approximation, where the scalar potentials are obtained based on the mass shifts of the respective mesons in nuclear matter. The mesons' mass shifts, the $^{12}$C nuclear density distributions, the strong potentials as well as the Coulomb potentials, are calculated by the quark-meson coupling (QMC) model.

nucl-th↗

arXiv2025

$B_c^{\pm}$-$^{12}$C states and detailed study of momentum space method for $Υ$- and $η_b$-nucleus bound states

We perform a detailed study of the $Υ$-, $η_b$-, and $B_c$-nucleus systems in momentum space to calculate the bound-state energies and the corresponding coordinate-space radial wave functions. The attractive strong potentials for the meson-nucleus systems are calculated from the Lorentz scalar mass modifications of these mesons in nuclear matter in the local density approximation in the nucleus. The downward shift of the meson masses may be regarded as a signature of partial restoration of chiral symmetry in a nuclear medium applied in the present study in an empirical sense, because the origin of the negative mass shift in this study is not directly related to the chiral symmetry mechanism. 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).

nucl-th↗

arXiv2024

In-medium mass shift of two-flavored heavy mesons, $B_c$, $B^_c$, $B_s$, $B^_s$, $D_s$ and $D^*_s$

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. This negative mass shift may be regarded as a signature of partial restoration of chiral symmetry in an empirical sense because the origin of the negative mass shift in the study is not directly related to the chiral symmetry mechanism. 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 $η_c (\bar{c} c)$ and $η_b (\bar{b} b)$, different from a naive expectation that it would be in between them. While, that of the $B_c^*$ shows the in between of the $J/ψ$ and $Υ$. 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 $D_s$.

hep-ph↗

arXiv2024

The equilibrium configurations of neutron stars in the optimized $f(R,T)$ gravity

We construct equilibrium configurations for neutron stars using a specific $f(R,T)$ functional form, recently derived through gaussian process applied to measurements of the Hubble parameter. By construction, this functional form serves as an alternative explanation for cosmic acceleration, circumventing the cosmological constant problem. Here, we aim to examine its applicability within the stellar regime. In doing so, we seek to contribute to the modified gravity literature by applying the same functional form of a given gravity theory across highly distinct regimes. Our results demonstrate that equilibrium configurations of neutron stars can be obtained within this theory, with the energy density and maximum mass slightly exceeding those predicted by General Relativity. Additionally, we show that the value of some parameters in the $f(R,T)$ functional form must differ from those obtained in cosmological configurations, suggesting a potential scale-dependence for these parameters. We propose that further studies apply this functional form across different regimes to more thoroughly assess this possible dependence.

gr-qc↗

arXiv2022

$Υ$ and $η_{b}$ mass shifts in nuclear matter and the nucleus bound states

The $Υ$ and $η_b$ as well as $B^*$ meson mass shifts (scalar potentials) are estimated for the first time in symmetric nuclear matter. The main interest is, whether or not the strengths of the bottomonium-nuclear matter and charmonium-nuclear matter interactions are similar or very different, in the range of a few tens of MeV at the nuclear matter saturation density. This is because, each ($Υ,J/Ψ$) and ($η_c,η_b$) meson group is usually assumed to have very similar properties based on the heavy charm and bottom quark masses. The estimate for the $Υ$ is made using an SU(5) effective Lagrangian density, by studying the $BB$, $BB^*$, and $B^*B^*$ meson loop contributions for the self-energy in free space and in nuclear medium. As a result, only the $BB$ meson loop contribution is included as our minimal prediction. As for the $η_b$, is included only the $BB^*$ meson loop contribution in the self-energy, to be consistent with the minimal prediction for the $Υ$. The in-medium masses of the $B$ and $B^{*}$ mesons appearing in the self-energy loops are calculated by the quark-meson coupling model. Form factors are used to regularize the loop integrals with a wide range of the cutoff mass values. The results suggest that both $Υ$ and $η_b$ should form bound states with a variety of nuclei considered in this study, for which the $Υ$-nucleus and $η_b$-nucleus bound state energies are calculated. The results also show an appreciable difference between the bottomonium-nuclear matter and charmonium-nuclear matter interaction strengths. Are also studied the $Υ$ and $η_b$ mass shifts in a heavy quark (heavy meson) symmetry limit. In addition, an initial study was done to investigate the influence of the choice of the form factor on our predictions.

nucl-th↗

arXiv2022

$Υ$ and $η_b$ nuclear bound states

$Υ$ and $η_b$ 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 $Υ$ and $η_b$ 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 $Υ$ and $η_b$ mesons should form bound states with all the nuclei considered.

nucl-th↗

arXiv2021

[1]Title: $Υ$ and $η_b$ mass shifts in nuclear matter and the $^{12}$C nucleus bound states, [2]Title: $Υ$ and $η_b$ mass shifts in nuclear matter and the nucleus bound states

[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 $Υ$ and $η_b$ 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 $Υ$- and $η_b$-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 $Υ$ and $η_b$ 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 $Υ$ and $η_b$ 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.

hep-ph↗

arXiv2021

\boldmath{$Υ$} and \boldmath{$η_b$} mass shifts in nuclear matter

We estimate the $Υ$, $η_b$ 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 ($J/Ψ,Υ$) and ($η_c,η_b$) meson group is usually assumed to have very similar properties based on the heavy charm and bottom quark masses. The estimate for the $Υ$ 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 $η_b$, 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 $Υ$ mass shift is made by comparing with the corresponding $DD, DD^*$, and $D^*D^*$ meson loops for the $J/Ψ$ mass shift. Our prediction for the $η_b$ mass shift is made including only the lowest order $BB^*$ meson loop. The $Υ$ mass shift, with including only the $BB$ loop, is predicted to be -16 to -22 MeV at the nuclear matter saturation density using the $ΥBB$ coupling constant determined by the vector meson dominance model with the experimental data, while the $η_b$ mass shift is predicted to be -75 to -82 MeV with the SU(5) universal coupling constant determined by the $ΥBB$ coupling constant. Our results show an appreciable difference between the bottomonium-(nuclear matter) and charmonium-(nuclear matter) interaction strengths. We also study the $Υ$ and $η_b$ mass shifts in a heavy quark (heavy meson) symmetry limit.

hep-ph↗