arXiv subjects

Laura Tolos

Publications and source records attributed to Laura Tolos.

123 records · Page 7Linked to original sources

arXiv2009

Charm and Hidden Charm Scalar Resonances in Nuclear Matter

We study the properties of the scalar charm resonances $D_{s0}(2317)$ and $D_0(2400)$, and the theoretical hidden charm state X(3700) in nuclear matter. We find that for the $D_{s0}(2317)$ and X(3700) resonances, with negligible and small width at zero density, respectively, the width becomes about $100 {\rm MeV}$ and $200 {\rm MeV}$ at normal nuclear matter density, accordingly. For $D_0(2400)$ the change in width is relatively less important. We discuss the origin of this new width and trace it to reactions occurring in the nucleus. We also propose a possible experimental test for those modifications in nuclear matter, which will bring valuable information on the nature of those scalar resonances and the interaction of $D$ mesons with nucleons.

nucl-th↗

arXiv2008

Strangeness and charm at FAIR

We study the properties of strange and charm mesons in hot and dense matter within a self-consistent coupled-channel approach for the experimental conditions of density and temperature expected for the CBM experiment at FAIR/GSI. The in-medium solution at finite temperature accounts for Pauli blocking effects, mean-field binding on all the baryons involved, and meson self-energies. In the strange sector, the $\bar K$ spectral function spreads over a wide range of energies, reflecting the melting of the $Λ(1405)$ resonance and the contribution of $(Λ,Σ,Σ^*)N^{-1}$ components at finite temperature. In the case of charm mesons, the dynamically-generated $Λ_c(2593)$ and $Σ_c(2880)$ resonances remain close to their free-space position while acquiring a remarkable width. As a result, the $D$ meson spectral density shows a single pronounced peak for energies close to the $D$ meson free-space mass that broadens with increasing matter density with an extended tail particularly towards lower energies. We also discuss the implications for the $D_{s0}(2317)$, $D_0(2400)$ and the predicted X(3700) resonances at FAIR energies.

hep-ph↗

arXiv2008

Charm mesons at FAIR

The in-medium properties of charm mesons ($D$ and $\bar D$) in a hot and dense matter are studied. A self-consistent coupled-channel approach is driven by a broken SU(4) s-wave Tomozawa-Weinberg interaction supplemented by an attractive isoscalar-scalar term. As medium effects, we include Pauli blocking, baryon mean-field bindings, and $π$ and open-charm meson self-energies. The dynamically generated $\tildeΛ_c$ and $\tildeΣ_c$ resonances in the $DN$ sector remain close to their free space position but acquire large widths. The resultant $D$ meson spectral function, which shows a single pronounced quasiparticle peak close to the free mass that broadens with increasing density, also has a long low energy tail associated with smeared $\tildeΛ_c N^{-1}$, $\tildeΣ_c N^{-1}$ configurations. The low-density approximation for the $\bar D N$ is questionable already at subsaturation densities. We touch upon the implication of our study for $J/Ψ$ suppression at FAIR.

nucl-th↗

arXiv2008

Open charm in nuclear matter at finite temperature

We study the properties of open-charm mesons ($D$ and $\bar {D}$) in nuclear matter at finite temperature within a self-consistent coupled-channel approach. The meson-baryon interactions are adopted from a type of broken SU(4) s-wave Tomozawa-Weinberg terms supplemented by an attractive scalar-isoscalar attraction. The in-medium solution at finite temperature incorporates Pauli blocking effects, mean-field binding on all the baryons involved, and $π$ and open-charm meson self-energies in a self-consistent manner. In the $DN$ sector, the $Λ_c$ and $Σ_c$ resonances, generated dynamically at 2593 MeV and 2770 MeV in free space, remain close to their free-space position while acquiring a remarkable width due to the thermal smearing of Pauli blocking as well as from the nuclear matter density effects. As a result, the $D$ meson spectral density shows a single pronounced peak for energies close to the $D$ meson free-space mass that broadens with increasing matter density with an extended tail particularly towards lower energies. The $\bar D$ potential shows a moderate repulsive behavior coming from the dominant I=1 contribution of the $\bar D N$ interaction. The low-density theorem is, however, not a good approximation for the $\bar D$ self-energy in spite of the absence of resonance-hole contributions close to threshold in this case. We speculate the possibility of $D$-mesic nuclei as well as discuss some consequences for the $J/Ψ$ suppression in heavy-ion collisions, in particular for the future CBM experiment at FAIR.

nucl-th↗

arXiv2007

Self-consistent coupled-channel approach to $D$ and $\bar D$ in hot dense matter

A self-consistent coupled-channel approach is used to study the properties of $D$ and $\bar D$ mesons in hot dense matter. The starting point is a broken SU(4) s-wave Tomozawa-Weinberg $DN$ ($\bar DN$) interaction supplemented by an attractive isoscalar-scalar term. The Pauli blocking effects, baryon mean-field bindings, and $π$ and open-charm meson self-energies are incorporated in dense matter at finite temperature. In the $DN$ sector, the dynamically generated $\tildeΛ_c$ and $\tildeΣ_c$ resonances remain close to their free space position while acquiring a remarkable width because of the thermal smearing of Pauli blocking. Therefore, the $D$ meson spectral density shows a single pronounced quasiparticle peak close to the free mass, that broadens with increasing density, and a low energy tail associated to smeared $\tildeΛ_c N^{-1}$, $\tildeΣ_c N^{-1}$ configurations. In the $\bar DN$ case, the low-density approximation to the repulsive $\bar D$ self-energy is found unreliable already at subsaturation densities. From this study we speculate the possible existence of $D$-mesic nuclei. We also discuss the consequences for $J/Ψ$ suppression at FAIR.

nucl-th↗

arXiv2007

$D$ and $\bar{D}$ mesons in hot and dense matter

The $D$ and $\bar {D}$ mesons are studied in hot dense matter within a self-consistent coupled-channel approach taking, as bare interaction, a broken SU(4) s-wave Tomozawa-Weinberg interaction supplemented by an attractive isoscalar-scalar term. The in-medium solution at finite temperature incorporates Pauli blocking effects, baryon mean-field bindings, and $π$ and open-charm meson self-energies. In the $DN$ sector, the $Λ_c$ and $Σ_c$ resonances remain close to their free-space position while acquiring a remarkable width. As a result, the $D$ meson spectral density shows a single pronounced peak close to the free mass that broadens with increasing density specially towards lower energies. The low-density theorem is not a good approximation for the repulsive $\bar D$ self-energy close to saturation density. We discuss the implications for the $J/Ψ$ suppression at CBM (FAIR).

nucl-th↗

arXiv2007

Neutron matter from low-momentum interactions

We present a perturbative calculation of the neutron matter equation of state based on low-momentum two- and three-nucleon interactions. Our results are compared to the model-independent virial equation of state and to variational calculations, and we provide theoretical error estimates by varying the cutoff used to regulate nuclear interactions. In addition, we study the dependence of the BCS $^1$S$_0$ superfluid pairing gap on nuclear interactions and on the cutoff. The resulting gaps are well constrained by the nucleon-nucleon scattering phase shifts, and the cutoff dependence is very weak for sharp or sufficiently narrow smooth regulators with cutoffs $\lm > 1.6 \fmi$.

nucl-th↗

arXiv2007

The in-medium $\bar K N$ interaction within a chiral unitary approach

The s- and p-wave contributions to the $\bar K N$ interaction in dense nuclear matter are obtained using a chiral unitary approach. We perform a self-consistent calculation of the $\bar K$ self-energy including Pauli blocking effects, meson self-energies modified by short-range correlations and baryon binding potentials. We find that the on-shell factorization cannot be applied to evaluate the in-medium corrections to p-wave amplitudes. Furthermore, the $Λ$ and $Σ$ develop a mass shift of -30 MeV at saturation density while the $Σ^*$ width increases to 80 MeV. We conclude that no deep and narrow $\bar K$ bound states could be observed.

nucl-th↗

arXiv2006

Chiral approach to antikaons in dense matter

Antikaons in dense nuclear matter are studied using a chiral unitary approach which incorporates the $s$- and p-waves of the $\bar K N$ interaction. We include, in a self-consistent way, Pauli blocking effects, meson self-energies modified by nuclear short-range correlations and baryon binding potentials. We show that the on-shell factorization cannot be applied to evaluate the in-medium corrections to p-wave amplitudes. We also obtain an attractive shift for the $Λ$ and $Σ$ masses of -30 MeV at saturation density while the $Σ^*$ width gets sensibly increased to about 80 MeV. The moderate attraction developed by the antikaon does not support the existence of very deep and narrow bound states.

nucl-th↗

arXiv2006

Open-charm enhancement at FAIR?

We have calculated the D-meson spectral density at finite temperature within a self-consistent coupled-channel approach that generates dynamically the $Λ_c$ (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.

nucl-th↗

arXiv2005

The effect of the in-medium $Θ^+$ pentaquark on the kaon optical potential

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, $K N \to Θ^+$, on the kaon optical potential is negligible due to the small width of the pentaquark. In contrast, the two-nucleon mechanism, $K N N \to Θ^+ N$, 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.

hep-ph↗

arXiv2005

The properties of the D-meson in dense matter

We study the D-meson spectral density in dense matter within the framework of a coupled-channel self-consistent calculation taking, as bare meson-baryon interaction, a separable potential. Our coupled-channel model generates dynamically the $Λ_c(2593)$ resonance. The medium modifications of the D-meson properties due to Pauli blocking and the dressing of D-mesons, nucleons and pions are also discussed. We found that the coupled-channel effects in the self-consistent process reduce the in-medium effects on the D-meson compared to previous works.

hep-ph↗

arXiv2004

Superfluidity of $Σ^-$ hyperons in $β$-stable neutron star matter

In this work we evaluate the $^1S_0$ energy gap of $Σ^-$ hyperons in $β$-stable neutron star matter. We solve the BCS gap equation for an effective $Σ^-Σ^-$ pairing interaction derived from the most recent parametrization of the hyperon-hyperon interaction constructed by the Nijmegen group. We find that the $Σ^-$ hyperons are in a $^1S_0$ superfluid state in the density region $\sim 0.27-0.7$ fm$^{-3}$, with a maximum energy gap of order 8 MeV at a total baryon number density of $\sim 0.37$ fm$^{-3}$ and a $Σ^-$ fraction of about 8%. We examine the implications on neutron star cooling.

nucl-th↗

arXiv2002

The antikaon nuclear potential in hot and dense matter

The antikaon optical potential in hot and dense nuclear matter is studied within the framework of a coupled-channel self-consistent calculation taking, as bare meson-baryon interaction, the meson-exchange potential of the Jülich group. Typical conditions found in heavy-ion collisions at GSI are explored. As in the case of zero temperature, the angular momentum components larger than L=0 contribute significantly to the finite temperature antikaon optical potential at finite momentum. It is found that the particular treatment of the medium effects has a strong influence on the behavior of the antikaon potential with temperature. Our self-consistent model, in which antikaons and pions are dressed in the medium, gives a moderately temperature dependent antikaon potential which remains attractive at GSI temperatures, contrary to what one finds if only nuclear Pauli blocking effects are included.

nucl-th↗

arXiv2000

Partial wave contributions to the antikaon potential at finite momentum

The momentum dependence of the antikaon optical potential in nuclear matter is obtained from a microscopic and self-consistent calculation using the meson-exchange Jülich $\bar{K}N$ interaction. Two self-consistent schemes are discussed, which would lead to substantially different predictions for the width of ${\bar K}$ nuclear bound states. The effect of higher partial waves of the $\bar{K}N$ interaction, beyond the L=0 component, is studied and found to have moderate but non-negligible effects on the ${\bar K}$ nuclear potential at zero momentum. At momenta as large as 500 MeV/c, relevant in the analysis of heavy-ion collisions, the higher partial partial waves modify the ${\bar K}$ optical potential by nearly a factor of two.

nucl-th↗