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We study odd parity J=1/2 and J=3/2 Ξc resonances using a unitarized coupled-channel framework based on a SU(6)lsf×HQSS-extended Weinberg–Tomozawa baryon–meson interaction, while paying a special attention to the renormalization procedure. We predict a large molecular ΛcK¯ component for the Ξc(2790) with a dominant 0− light-degree-of-freedom spin configuration. We discuss the differences between the 3/2− Λc(2625) and Ξc(2815) states, and conclude that they cannot be SU(3) siblings, whereas we predict the existence of other Ξc-states, one of them related to the two-pole structure of the Λc(2595). It is of particular interest a pair of J=1/2 and J=3/2 poles, which form a HQSS doublet and that we tentatively assign to the Ξc(2930) and Ξc(2970), respectively. Within this picture, the Ξc(2930) would be part of a SU(3) sextet, containing either the Ωc(3090) or the Ωc(3119), and that would be completed by the Σc(2800). Moreover, we identify a J=1/2 sextet with the Ξb(6227) state and the recently discovered Σb(6097). Assuming the equal spacing rule and to complete this multiplet, we predict the existence of a J=1/2 Ωb odd parity state, with a mass of 6360 MeV and that should be seen in the ΞbK¯ channel.
We review the effective field theory associated with the superfluid phonons that we use for the study of transport properties in the core of superfluid neutrons stars in their low temperature regime. We then discuss the shear and bulk viscosities together with the thermal conductivity coming from the collisions of superfluid phonons in neutron stars. With regard to shear, bulk, and thermal transport coefficients, the phonon collisional processes are obtained in terms of the equation of state and the superfluid gap. We compare the shear coefficient due to the interaction among superfluid phonons with other dominant processes in neutron stars, such as electron collisions. We also analyze the possible consequences for the r-mode instability in neutron stars. As for the bulk viscosities, we determine that phonon collisions contribute decisively to the bulk viscosities inside neutron stars. For the thermal conductivity resulting from phonon collisions, we find that it is temperature independent well below the transition temperature. We also obtain that the thermal conductivity due to superfluid phonons dominates over the one resulting from electron-muon interactions once phonons are in the hydrodynamic regime. As the phonons couple to the Z electroweak gauge boson, we estimate the associated neutrino emissivity. We also briefly comment on how the superfluid phonon interactions are modified in the presence of a gravitational field or in a moving background.
The kaon nuclear optical potential is studied including the effect of the Θ+ pentaquark. The one-nucleon contribution is obtained using an extension of the Jülich meson-exchange potential as bare kaon–nucleon interaction. Significant differences between a fully self-consistent calculation and the usually employed low-density Tρ approach are observed. The influence of the one-nucleon absorption process, KN→Θ+, on the kaon optical potential is negligible due to the small width of the pentaquark. In contrast, the two-nucleon mechanism, KNN→Θ+N, estimated from the coupling of the pentaquark to a two-meson cloud, provides the required amount of additional kaon absorption to reconcile with data the systematically low K+-nucleus reaction cross sections found by the theoretical models.
We address the modification of open heavy-flavor mesons in a hot medium of light mesons within an effective theory approach consistent with chiral and heavy-quark spin-flavor symmetries and the use of the imaginarytime formalism to introduce the non-zero temperature effects to the theory. The unitarized scattering amplitudes, the ground-state self-energies and the corresponding spectral functions are calculated self-consistently. We use the thermal ground-state spectral functions obtained with this methodology to further calculate 1) open-charm meson Euclidean correlators, and 2) off-shell transport coefficients in the hadronic phase.
The present status in the field of strange mesons in nuclei and neutron stars is reviewed. In particular, the K̅N interaction, that is governed by the presence of the Λ(1405), is analyzed and the formation of the K̅NN bound state is discussed. Moreover, the properties of K̅ in dense nuclear matter are studied, in connection with strangeness production in nuclear collisions and kaon condensation in neutron stars.
The dynamics of strange pseudoscalar and vector mesons in hot and dense nuclear matter is studied within a chiral unitary framework in coupled channels. Our results set up the starting point for implementations in microscopic transport approaches of heavy-ion collisions, particularly at the conditions of the forthcoming experiments at GSI/FAIR and NICA-Dubna. In the K̄ N sector we focus on the calculation of (off-shell) transition rates for the most relevant binary reactions involved in strangeness production close to threshold energies, with special attention to the excitation of sub-threshold hyperon resonances and isospin effects (e.g. K̄ p vs K̄ n). We also give an overview of recent theoretical developments regarding the dynamics of strange vector mesons (K*, K̄* and ϕ) in the nuclear medium, in connection with experimental activity from heavy-ion collisions and nuclear production reactions. We emphasize the role of hadronic decay modes and the excitation of hyperon resonances as the driving mechanisms modifying the properties of vector mesons.
We have calculated the D-meson spectral density at finite temperature within a self-consistent coupled-channel approach that generates dynamically the Lambda_c (2593) resonance. We find a small mass shift for the D-meson in this hot and dense medium while the spectral density develops a sizeable width. The reduced attraction felt by the D-meson in hot and dense matter together with the large width observed have important consequences for the D-meson production in the future CBM experiment at FAIR.
The properties of strange pseudoscalar and vectors mesons as well as strange baryon resonances in dense matter are reviewed. Some open questions on the properties of strange hadrons in medium are addressed, such as the experimental signatures of inmedium effects coming from the hadronic phase on the final observables in heavy-ion collisions for the experimental conditions at SIS, RHIC and LHC energies.
We obtain the D-meson spectral density at finite temperature for the conditions of density and temperature expected at FAIR. We perform a self-consistent coupled-channel calculation taking, as a bare interaction, a separable potential model. The Lambda_c (2593) resonance is generated dynamically. We observe that the D-meson spectral density develops a sizeable width while the quasiparticle peak stays close to the free position. The consequences for the D-meson production at FAIR are discussed.