arXiv subjects

Fernando E. Serna

Publications and source records attributed to Fernando E. Serna.

22 records · Page 2Linked to original sources

arXiv2017

Charmed mesons with a symmetry-preserving contact interaction

A symmetry-preserving treatment of a vector-vector contact interaction is used to study charmed heavy-light mesons. The contact interaction is a representation of nonperturbative kernels used in Dyson-Schwinger and Bethe-Salpeter equations of QCD. The Dyson-Schwinger equation is solved for the $u,\,d,\,s$ and $c$ quark propagators and the bound-state Bethe-Salpeter amplitudes respecting spacetime-translation invariance and the Ward-Green-Takahashi identities associated with global symmetries of QCD are obtained to calculate masses and electroweak decay constants of the pseudoscalar $π,\,K$, $D$ and $D_s$ and vector $ρ$, $K^*$, $D^*$, and $D^*_s$ mesons. The predictions of the model are in good agreement with available experimental and lattice QCD data.

hep-ph↗

arXiv2016

Charmed mesons at finite temperature and chemical potential

We compute the masses of the pseudoscalar mesons $π^+$ , $K^0$ and $D^+$ at finite temperature and baryon chemical potential. The computations are based on a symmetry- preserving Dyson-Schwinger equation treatment of a vector-vector four quark contact interaction. The results found for the temperature dependence of the meson masses are in qualitative agreement with lattice QCD data and QCD sum rules calculations. The chemical potential dependence of the masses provide a novel prediction of the present computation.

nucl-th↗

arXiv2016

Shear and Bulk Viscosities of Quark Matter from Quark-Meson Fluctuations in the Nambu--Jona-Lasinio model

We have calculated the temperature dependence of shear $η$ and bulk $ζ$ viscosities of quark matter due to quark-meson fluctuations. The quark thermal width originating from quantum fluctuations of quark-$π$ and quark-$σ$ loops at finite temperature is calculated with the formalism of real-time thermal field theory. Temperature-dependent constituent-quark and meson masses, and quark-meson couplings are obtained in the Nambu--Jona-Lasinio model. We found a non-trivial influence of the temperature-dependent masses and couplings on the Landau-cut structure of the quark self-energy. Our results for the ratios $η/s$ and $ζ/s$, where $s$ is the entropy density (also determined in the Nambu--Jona-Lasinio model in the quasi-particle approximation), are in fair agreement with results of the literature obtained from different models and techniques. In particular, our result for $η/s$ has a minimum very close to the conjectured AdS/CFT lower bound, $η/s = 1/4π$.

nucl-th↗

arXiv2016

Excited hadrons and the analytical structure of bound-state interaction kernels

We highlight Hermiticity issues in bound-state equations whose kernels are subject to a highly asymmetric mass and momentum distribution and whose eigenvalue spectrum becomes complex for radially excited states. We trace back the presence of imaginary components in the eigenvalues and wave functions to truncation artifacts and suggest how they can be eliminated in the case of charmed mesons. The solutions of the gap equation in the complex plane, which play a crucial role in the analytic structure of the Bethe-Salpeter kernel, are discussed for several interaction models and qualitatively and quantitatively compared to analytic continuations by means of complex-conjugate pole models fitted to real solutions.

nucl-th↗