arXiv subjects

D. Espinosa-Gomez

Publications and source records attributed to D. Espinosa-Gomez.

3 recordsLinked to original sources

arXiv2023

Decay of the Z' gauge boson with lepton flavor violation

The flavor-violating decay of a new neutral massive gauge boson $Z^\prime\toμe$ is analyzed in the context of extended models, in which this particle emerges. By means of the analysis of the $μ\to eγ$ decay, $μ-e$ conversion process in nuclei and the $μ\to e e^{+}e^{-}$ decay, the strength of the $Z^\primeμe$ coupling is estimated and used to calculate the branching ratio of the $Z^\prime\to μe$ decay. This is done for the so-called $Z_S,\,Z_{LR},\,Z_χ, Z_ψ$ and $Z_η$ bosons. We found that, through the $μ-e$ conversion process, the most restrictive bound for the coupling is provided by the $Z_{LR}$ boson. Meanwhile, by means of the $μ\to e e^{+}e^{-}$ decay, the most restrictive bound for the $Z^\primeμe$ coupling is provided by the $Z_χ$ boson. However, if we concentrate on the less restrictive prediction for the Br($Z^\prime\to μe$), this comes from the $Z_η$ boson and the resulting branching ratio is less than $10^{-4}$. On the other hand, if we consider the most restrictive bound, the branching ratio for the process is below $2\times 10^{-7}$, which results from the $Z_{RL}$ boson, and is obtained through the $μ-e$ conversion process.

hep-ph↗

arXiv2020

Rare decays of the top quark mediated by Z' gauge bosons and flavor violation

The rare top quark decays mediated by a new neutral massive gauge boson that is predicted in models with extended gauge symmetries are studied. We focus on the processes $t\to cV, uV$ induced at the one loop level, where $V =γ, g$, by considering different extended models. It is found that, within a broad range of mass of the new neutral gauge boson, the models predict branching ratios for the decays in study that are competitive with respect to the corresponding branching ratios in the standard model. In order to establish bound on our branching ratios, we consider the recent experimental bounds as $m_{Z^\prime}\geq$ 3.8-4.5 TeV, depending on the model, which also impose restrictions on our calculation. Even in this case, the resulting branching ratios are of the same order of magnitude as that predicted by the standard model. It should be noted that for the case of two models studied here, since no experimental bound exists to compare with, the results could be important, as they are, in the best of cases, two orders of magnitude larger than the predicted by the standard model.

hep-ph↗

arXiv2018

Flavor violation in chromo- and electromagnetic dipole moments induced by $Z^\prime$ gauge bosons and a brief revisit of the Standard Model

The electromagnetic dipole moments of the tau lepton and the chromoelectromagnetic dipole moments of the top quark are estimated via flavor-changing neutral currents, mediated by a new neutral massive gauge boson. We predict them in the context of models beyond the Standard Model with extended current sectors, in which simple analytic expressions for the dipole moments are presented. For the different $Z^\prime$ gauge boson considered, the best prediction for the magnetic dipole moment of the tau lepton, $|a_τ|$, is of the order of $10^{-8}$, while the highest value for the electric one, $|d_τ|$, corresponds to $10^{-24}$ $e\,$cm; our main result for the chromomagnetic dipole moment of the top quark, $|\hatμ_t|$, is $10^{-6}$, and the value for the chromoelectric one, $|d_t|$, can be as high as $10^{-22}$ $e\,$cm. We compare our results, revisiting the corresponding Standard Model predictions, in which the chromomagnetic dipole moment of the top quark is carefully evaluated, finding explicit imaginary contributions.

hep-ph↗