Density Of Nuclear Medium Research Articles

Fate of the doubly heavy spin- 3/2 baryons in a dense medium

We investigate the behavior of the doubly heavy spin$-3/2$ baryons in cold nuclear matter. In particular, we study the variations of the spectroscopic parameters of the ground state $\Xi^*_{QQ'}$ and $\Omega^*_{QQ'}$ particles, with $ Q $ and $ Q' $ being $b $ or $ c $ quark, with respect to the changes in the density of the nuclear medium. We find the shifts on the parameters under question at saturation medium density compared to their vacuum values. It is observed that the parameters of the $\Xi^*_{QQ'}$ states containing two heavy quarks and one up or down quark are affected by the medium, considerably. The parameters of the $\Omega^*_{QQ'}$ states containing two heavy quarks and one strange quark, however, do not show any sensitivity to the density of the cold nuclear medium. We also discuss the variations of the vector self-energy at each channel with respect to the changes in the density. The negative shifts in the mass of $\Xi^*_{QQ'}$ states due to nucleons in the medium can be used to study the doubly heavy baryons' interactions with the nucleons. The results obtained can also be used in analyses of the results of the future in-medium experiments.

Formula omitted] meson propagation in dense nuclear matter and collective excitations

The bosonic excitations induced by the ω meson propagation in dense nuclear matter is studied within the framework of random phase approximation. The collective modes are then analyzed by finding the zeros of the relevant dielectric functions. Subsequently we present closed form analytical expressions for the dispersion relations in different kinematical regime. Next, the analytical behaviour of the in-medium effective propagator for the ω meson is examined. This is exploited to calculate the full spectral function for the transverse ( T) and longitudinal ( L) mode of the ω meson. In addition, various sum rules are constructed for the ω meson spectral density in nuclear medium. Results are then discussed by calculating the residues at the poles and discontinuities across the cuts.

Vector mesons in dense matter

We will summarize the progress in understanding the changes in the vector meson spectral density in nuclear medium using the constraint equations obtained from the Borel transformed dispersion relation and QCD Operator Product Expansion. We will discuss the results for the scalar mass shift and dispersion effects (three momentum dependence) for the light quark system (ϱ,ω), the strange quark system (Φ) and the heavy quark system ( J/ψ) in nuclear medium. For the light quark system, a nontrivvial change in the mass and width is expected, while the dispersion effects are found to be small. Existing model calculations for the dispersion effects are compared to the constraint equation in detail. Very small, but accurate mass shifts are obtained for the heavy quark system.

Erratum: Vector mesons in the nuclear medium with a finite three-momentum [Phys. Rev. C57, 927 (1998)

We formulate a QCD sum rule to find the three momentum dependence of the peak position of the vector meson spectral density in nuclear medium. We find less than 2 % (0.1 %) shift of the peak position at nuclear matter density and at ($q =0.5$GeV/c) for the $\rho,\omega (\phi$) mesons. However, at higher density and three momentum, its effect becomes non-negligible. The relevance of our result in the dilepton spectrum in A-A and p-A reaction is discussed.

Vector mesons in nuclear medium with small three momentum, a QCD sum rule approach

Using the QCD Operator Product Expansion, we derive the real part of the transverse and longitudinal vector vector correlation function with the ϱ, ω quantum numbers to leading order in density and in q 2 at −gw 2 → ∞. To dimension 6, only twist-2 and 4 operators contribute. These OPE, through the energy dispersion relation, provide model independent constraints for the q dependence of the vector meson spectral density in nuclear medium. We further make a QCD sum rule type of analysis to extract the momentum dependence of the vector meson dispersion relation in medium. The contributions from twist-2 operators are added up to infinite order to check the validity of the OPE at the relevant Borel window.

A Relativistic Calculation of Non-Mesonic Decay of the Particle in Nuclear Medium

Relativistic calculations of the non-mesonic decay of the Λ particle in nuclear medium are compared with those under the non-relativistic and static approximations. Near the normal density of nuclear medium, the relativistic results give considerably larger decay rates and neutron/proton ratios than non-relativistic ones