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### Browsing by Author "Neves, M.J."

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Item THE PROTOPHOBIC X-BOSON COUPLED TO QUANTUM ELECTRODYNAMICS(Jagiellonian University Press, 2020) Neves, M.J.; Abreu, E.M.C.; Helayël-Neto, J.A.; University of Alabama Tuscaloosa; Universidade Federal Rural do Rio de Janeiro (UFRRJ); Universidade Federal de Juiz de Fora; Universidade Federal do Rio de JaneiroShow more The possible origin of an \(X\)-boson having a mass value around 17 MeV had motivated us to investigate its interaction with leptons of QED. This new hypothetical particle can possibly be a candidate to describe the so-called fifth interaction in a new physics scenario beyond the Standard Model. The simplest \(X\)-boson model unified to the Standard Model is based on an \(\mathrm {SU}_{c}(3) \times \mathrm {SU}_{L}(2) \times \mathrm {U}_{Y}(1) \times \mathrm {U}(1)_{B-L}\) symmetry, where the group \(\mathrm {U}(1)_{B-L}\) is attached to the \(X\)-boson, with a kinetic mixing with the gauge field of \(\mathrm {U}_{Y}(1)\). The Higgs sector was revisited to generate the mass for the new boson. Thus, the mass of 17 MeV fixes a vacuum expected value scale. Thereby, we could estimate the mass of the hidden Higgs field through both the VEV-scale and the Higgs’ couplings. A model of QFT was constructed in a renormalizable \(R_{\xi }\)-gauge, and we analyze its perturbative structure. After that, the radiative correction of the \(X\)-boson propagator has been calculated at one-loop approximation to yield the Yukawa potential correction. The form factors associated with the QED-vertex correction were calculated to confirm the electron’s anomalous magnetic moment together with the computation of the interaction magnitude. The muon case was discussed. Furthermore, we have introduced a renormalization group scheme to explore the running \(X\)-boson mass and its coupling constant with the leptons of the Standard Model.Show more Item Testing Lorentz-symmetry violation via electroweak decays(American Physical Society, 2020) Gomes, Y.M.P.; Malta, P.C.; Neves, M.J.; Centro Brasileiro de Pesquisas Fisicas; University of Alabama Tuscaloosa; Universidade Federal Rural do Rio de Janeiro (UFRRJ)Show more In this work we introduce \(CPT\)-odd nonminimal Lorentz-symmetry violating couplings to the electroweak sector modifying the interaction between leptons and gauge bosons. The vertex rules allow us to calculate tree-level processes modified by the presence of the novel dimension-five operators. For definitiveness, we investigate the \(W\) decay into a lepton-neutrino pair, the \(Z\) decay into pairs of charged and neutral leptons, as well as the decay of the muon. By comparing the experimental measurements on these processes to our results we are able to bound several combinations of the background 4-vectors to be \(\lesssim {10}^{-4}\text{}\text{}{\mathrm{GeV}}^{-1}\).Show more