arXiv subjects

G. Toledo Sánchez

Publications and source records attributed to G. Toledo Sánchez.

3 recordsLinked to original sources

arXiv2017

Absorptive corrections for vector mesons. Matching to complex mass scheme and longitudinal corrections

Unstable spin-1 particles are properly described by including absorptive corrections to the electromagnetic vertex and propagator, without breaking the electromagnetic gauge invariance. We show that the modified propagator can be set into a complex mass form, provided the mass and the width parameters, which are properly defined at the pole position, are replaced by energy dependent functions fulfilling the same requirements at the pole. We exemplify the case for the $K^*(892)$ vector meson, where the mass function deviates around 2 MeV from the $Kπ$ threshold to the pole position. The absorptive correction depends on the mass of the particles in the loop. For vector mesons, whose main decay is into two pseudoscalar mesons ($PP'$), the flavor symmetry breaking induces a correction to the longitudinal part of the propagator. Considering the $τ^- \to K_Sπ^-ν_τ$ decay, we illustrate these corrections by obtaining the modified vector and scalar form factors. The $K_Sπ^-$ spectrum is described considering the $K^*(892)$ and $K^{'*}(1410)$ vectors and one scalar particle. Nonetheless, for this case, the correction to the scalar form factor is found to be negligible.

hep-ph↗

arXiv2015

Determination of the magnetic dipole moment of the rho meson using 4 pion electroproduction data

We determine the magnetic dipole moment of the rho meson using preliminary data from the BaBar Collaboration for the $e^+ e^- \to π^+ π^- 2 π^0$ process, in the center of mass energy range from 0.9 to 2.2 GeV. We describe the $γ^* \to 4π$ vertex using a vector meson dominance model, including the intermediate resonance contributions relevant at these energies. We find that $μ_ρ= 2.1 \pm 0.5$ in $e/2 m_ρ$ units.

hep-ph↗

arXiv2004

A simple variational approach for an interacting Fermi trapped gas

Quantum states of a two-component Fermi trapped gas are described by introducing an effective trap frequency, determined via variational techniques. Closed expressions for the contribution of a contact interaction potential to the total energy and the pairing interaction are derived. They are valid for both few and large number of particles, given the discrete nature of the formulation, and therefore richer than the continuous expressions, which are perfectly matched. Pairing energies within a shell are explicitly evaluated and its allowed values at a given energy level delimited. We show the importance of the interaction over the trap energy as the number of particles ($N$) grows and the temperature decreases. At zero temperature we find a polynomial dependence of the interaction energy on the Fermi energy, whose dominant term at large $N$ corresponds with the mean field approximation result. In addition, the role of the strength of an attractive potential on the total energy is exhibited.

cond-mat.other↗