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R. Martinez

Publications and source records attributed to R. Martinez.

At least 19 recordsLinked to original sources

Implications of the muon anomalous magnetic moment in a Doublet Left-Right Symmetric Model

We compute the complete set of one-loop contributions to the muon anomalous magnetic moment, $a_{\mu}=(g-2)_{\mu}/2$, in the Doublet Left-Right Symmetric Model (DLRSM), based on the gauge group $SU(2)_{L}\otimes SU(2)_{R}\otimes U(1)_{B-L}$ with neutrino masses generated via the inverse seesaw (ISS) mechanism. We evaluate all four one-loop topologies VFF, SFF, FVV, and FSS arising from the extended gauge bosons ($W^{\prime}$, $Z^{\prime}$), the new scalar sector ($H_{3}^{0}$, $A_{1}^{0}$, $H_{R}^{\pm}$, $H_{L}^{\pm}$), and the heavy neutrino spectrum generated by the ISS mechanism, using the Casas--Ibarra parametrization to express the neutrino mixing in terms of physical observables. Imposing the experimental bound on $\Delta a_{\mu}$, we establish that $v_{R}\lesssim1$ TeV is excluded, implying lower bounds $m_{W^{\prime}}\gtrsim325$ GeV, $m_{Z^{\prime}}\gtrsim385$ GeV, and $m_{N}\gtrsim700$ GeV under the manifest left-right symmetry condition $g_{R}=g_{L}$. Relaxing this condition to $g_{R}\neq g_{L}$ strengthens the gauge boson bounds to $m_{W^{\prime}}\gtrsim1625$ GeV and $m_{Z^{\prime}}\gtrsim1650$ GeV.

hep-ph

Constraints from muon $g-2$ on a gauged non-universal $U(1)_{X}$ model with inverse see-saw neutrinos

We study the effects on a non-universal $U(1)_{X}$ extension of the Standard Model given the alternative value obtained by the Budapest-Marseille-Wuppertal (BMW) group for the anomalous magnetic moment of the muon $g-2$. The model explains the fermion mass hierarchy through the non-universality of the extra gauge symmetry and by an additional $\mathbb{Z}_{2}$ discrete symmetry, where the heaviest fermions acquire their masses from two different scales determined by two Higgs doublets and one singlet, whereas the lightest fermions obtain their masses from radiative corrections. From cancellation of chiral anomalies, the model also includes heavy extra fermions, both charged and neutral. The latter are right-handed neutrinos that acquire masses via an inverse see-saw mechanism, reproducing the observed squared mass differences for the active neutrinos. Using the latest lattice calculation of the leading hadronic vacuum polarization (HVP) contribution to the muon $g-2$, we compute the dominant one-loop diagrams mediated by the $W$ and charged Higgs bosons, both with a heavy Majorana neutrino in the loop, setting bounds for masses of the new particles. We also provide predictions for observables that can probe our model in the future such as charged lepton flavor violating searches at Belle II like $\tau\to \mu\gamma$, $\tau\to e\gamma$ and at MEG II for $\mu\to e\gamma$.

hep-ph

Light quark contributions to Higgs decays

The literature establishes that the light fermions contributions to the decays $H\to Z\gamma$ and $H\to\gamma\gamma$ are negligible since their coupling with the Higgs is proportional to $m_f$. In the present letter, we show that although such a conclusion is true for leptons, the light quark contributions are zero when we consider their non-perturbative effects.

hep-ph

Lepton Flavor-Violating Higgs Decays Mediated by Ultralight Gauge Boson

We present an analysis of the lepton-flavor violating decay of the Higgs boson mediated by an ultralight gauge boson, $\chi$. Our analysis matches a model generating the lepton flavor-violating interaction $\bar{\ell}_i\ell_j\chi$ at tree level with an effective field theory, safeguarding a physical massless $\chi$-boson limit of the observables. By utilizing the upper bounds on $H\to\ell_i \bar\ell_j$ decays from CMS and ATLAS Collaborations, we establish an indirect upper limit on the nonstandard decay $H\to\ell_i \bar\ell_j\chi$. The analysis encompasses various observables such as the lepton energy spectrum, Dalitz plot distribution, and Lepton Charge and Forward-Backward Asymmetries.

hep-ph

$H\rightarrow Z\gamma$ decay and $CP$ violation

This study examines the impact of $CP$-violation on the signal strength $\mu^{Z\gamma}$, which was reported as $2.2\pm 0.7$ by the LHC. We obtain constraints on the real and absorptive parts of the $CP$-violating form factor $h_3^{Z\gamma}$ and find that they are less than 1.15 GeV. Additionally, we revisit the leading order Standard Model contributions to the $H\rightarrow Z\gamma$ decay and calculate contributions to $h_3^{Z\gamma}$ from FCNC complex couplings mediated by the $Z$ and $H$ bosons. By using the current bounds on such couplings, we find that the FCNC contribution to $h_3^{Z\gamma}$ with top and charm quarks in the loop is of order $10^{-5}$ GeV. While in a model with new quarks that preserves the SM predictions on Higgs decays, the $CP$-violating form factor $h_3^{Z\gamma}$ can be of order $10^{-1}$ GeV and could explain the excess on the signal strength $\mu^{Z\gamma}$.

hep-ph

$B$ meson anomalies and large $B^{+}\to K^{+}\nu\bar{\nu}$ in non-universal $U(1)^\prime$ models

In view of both the latest LHCb measurement of $R_{K^{(*)}}$ and the new $2.8\sigma$ deviation reported by Belle II on $B^{+}\to K^{+}\nu\bar{\nu}$ decays, we present a fit to the $B$ meson anomalies for various one and two dimensional hypothesis including complex Wilson coefficients. We show in a model-independent way that the generic non-universal $U(1)^{\prime}$ extensions of the SM, without flavour violation, fail to simultaneously fit those observables and corroborate that they can modify $\mathrm{BR}(B^{+}\to K^{+}\nu\bar{\nu})$ up to only a $10\%$. In view of this deficit, we propose a new way in which those models can accommodate the data at tree level by introducing lepton flavour violating couplings and non-diagonal elements of the charged lepton mixing matrix, with implications in future charged lepton flavour violation searches.

hep-ph

A gauged non-universal $U(1)_{X}$ model to study muon $g-2$ and $B$ meson anomalies

We study a non-universal $U(1)_{X}$ extension of the Standard Model with an extended scalar sector of two doublets and one singlet plus three additional exotic quarks and two exotic charged leptons on the fermionic sector. In order to obtain the observed fermion mass hierarchy, an additional $\mathbb{Z}_{2}$ discrete symmetry is imposed, where the heaviest fermions acquire their masses from three different scales determined by two Higgs doublets and one singlet, whereas the lightest fermions obtain their masses from effective operators up to dimension seven. From chiral anomalies cancellation, the model also includes heavy right-handed neutrinos which get massive via an inverse see-saw mechanism, reproducing the observed mass differences for the active neutrinos. We analyze phenomenological consequences of the model in view of the so-called flavour anomalies, namely the latest measurement made by Fermilab of the anomalous magnetic moment of the muon $g-2$, and additionally, the fit to semi-leptonic $B$ meson decays made by different flavour groups, dominated mainly by the LHCb 2020 data. We obtain that the model can explain the former at the $1σ$ level by means of contributions coming from charged $W^{+}$ bosons interacting with exotic Majorana neutrinos at one-loop level, with the $Z'$ boson contribution itself coming from the $U(1)_X$ symmetry being negligible. However, we find that the model is able to accommodate the $b\to s\ell^{+}\ell^{-}$ transitions associated to the $B$ meson anomalies only at the $2σ$ level via tree-level $Z'$ boson exchange, while simultaneously respecting various constraints from the recent $R_{K^{(*)}}$ measurements made by the LHCb, neutrino trident production and $B-\bar B$ oscillations.

hep-ph

Flavored axions and the flavor problem

A Peccei-Quinn~(PQ) symmetry is proposed in order to generate in the Standard Model~(SM) quark sector a realistic mass matrix ansatz with five texture-zeros. Limiting our analysis to Hermitian mass matrices, we show that this requires a minimum of 4 Higgs doublets. This model allows assigning values close to 1 for several Yukawa couplings, giving insight into the origin of the mass scales in the SM. Since the PQ charges are non-universal, the model features Flavor-Changing Neutral Currents~(FCNC) at the tree level. From the analytical expressions for the FCNC we report the allowed region in the parameter space obtained from the measurements of branching ratios of semileptonic meson decays.

hep-ph

Lepton masses in a non universal U(1) model with three families

We present an extension $U(1)_{X}$ to the Standard Model that reproduces the lepton mass structures determined by the experiments. In the charged sector, we introduced effective operators of dimension $n = 7$ to generate the mass of the electron, which is null at tree-level due to the $X$ charge. In the neutral sector, we added three sterile right-handed neutrinos and three Majorana neutrinos to generate the mass structure for the left-handed neutrinos, by the inverse seesaw mechanism. The model free parameters were fitted with the known mass eigenvalues $m_{e},\,m_μ,\,m_τ$, and with the most recent results of a global analysis of the data from neutrino oscillation. From the adjustment of the free parameters, we obtained allowed regions for the Yukawa coupling set.

hep-ph

On perturbative aspects of a nonminimal Lorentz-violating QED with CPT-odd dimension-5 terms

We consider the Lorentz-violating extended QED involving all nonminimal dimension-5 additive CPT-odd terms. For this theory, we investigate the possibility of generating the Carroll-Field-Jackiw (CFJ) term of the first order in any of these nonminimal couplings. This term is demonstrated to vanish in certain regularization schemes. We also study the question of higher-derivative divergent contributions and demonstrate that they can be eliminated by considering a given proportionality between the coefficients.

hep-th

PMNS matrix in a non-universal $U(1)_{X}$ extension to the MSSM with one massless neutrino

An anomaly free non-universal $U(1)_{X}$ extension to the Minimal Supersymmetric Standard Model is proposed, where additional two $SU(2)$ doublet superfields and four singlet superfields complement the scalar sector of the model. The fermion sector is extended by considering additional superfields containing three quark singlets, two charged lepton singlet superfields and six neutral leptons. A tree-level massless electron is found so radiative corrections are considered to match the mass spectrum with both SUSY and non-SUSY contributions. Likewise, a massless neutrino is found and analytic expressions for massive mass eigenstates are obtained via inverse-seesaw mechanism, which implies a known neutrino mass spectrum for both normal and inverse ordering. Lastly, a numerical fitting of the model parameters to the PMNS matrix is done.

hep-ph

$\tildeν$ contributions to electron and muon EDM in an Inverse Seesaw Mechanism

A non-universal anomaly free $U(1)_{X}$ extension to the Minimal Supersymmetric Standard Model, consisting of four scalar doublets, four scalar singlets and additional quark and lepton singlets including right-handed and Majorana neutrinos, is used to determine the contributions to the electron and muon Electric Dipole Moment. The additional CP violation sources come from the lepton sector, where neutrino masses are explained by an Inverse Seesaw Mechanism and the CP violating phase of the PMNS matrix generates complex interactions that involves exotic neutrino and sneutrino mass eigenstates. Such contributions are studied at one and two-loop level by considering the associated Barr-Zee diagrams and their supersymmetric counterpart. At one-loop level, it is found that the Electric Dipole Moment fixes a relationship between chargino and sneutrino masses depending on which particles have a mass bellow $10^{6}$ GeV. At two loop level, contributions are comparable to the one-loop contributions but the integrals diverge in some cases, yielding additional restrictions such as no degenerate sneutrino masses and they should be heavier than chargino masses.

hep-ph

Explaining muon $g-2$ anomaly in a non-universal $U(1)_{X}$ extended SUSY theory

A non-universal $U(1)_{X}$ extension to the Standard Model composed of two scalar doublets and two scalar singlets together with three additional quark singlets and two lepton singlets and three generations of right-handed and Majorana neutrinos is made to explain lepton mass hierarchy, neutrino masses via inverse seesaw mechanism and muon anomalous magnetic moment in an anomaly free framework. In the present model, exotic and Standard Model particles acquire mass thanks to vacuum expectation values at different scales, yet the electron and the lightest neutrino are tree level massless but massive at one-loop level. By considering a numerical exploration and under the constraint of the Higgs mass, neutrino mass differences and PMNS matrix, it is found that only contributions due to exotic neutrinos interacting with charged scalars are relevant to muon $g-2$, though they are negative. Thus, the SUSY extension is considered and it is found that muon $g-2$ can be explained by allowing $U(1)_{X}$ vacuum expectation values to lie in the TeV scale thanks to SUSY soft-breaking interactions for at least $\sim 10^{5}$ GeV masses. Thus, the contribution due to exotic neutrinos interacting with $W$ gauge bosons is positive and no longer negligible which added to all other contributions might explain the anomaly.

hep-ph

Dark matter in Inert Doublet Model with one scalar singlet and $U(1)_X$ gauge symmetry

We study Dark Matter (DM) abundance in the framework of the extension of the Standard Model (SM) with an additional $U(1)_X$ gauge symmetry. One complex singlet is included to break the $U(1)_X$ gauge symmetry, meanwhile one of the doublets is considered inert to introduce a DM candidate. The stability of the DM candidate is analyzed with a continuous $U(1)_X$ gauge symmetry as well as discrete $Z_2$ symmetry. We find allowed regions for the free model parameters which are in agreement with the most up-to-date experimental results reported by CMS and ATLAS collaborations, the upper limit on WIMP-nucleon cross section imposed by XENON1T collaboration and the upper limit on the production cross-section of a $Z^{\prime}$ gauge boson times the branching ratio of the $Z^{\prime}$ boson decaying into $\ell^-\ell^+$. We also obtain allowed regions for the DM candidate mass from the relic density reported by the PLANCK collaboration including light, intermediate and heavy masses; depending mainly on two parameters of the scalar potential, $λ_{2x}$ and $λ_{345}=λ_3+λ_4+2λ_5$. We find that trough $pp\rightarrow χχγ$ production, it may only be possible for a future hadron-hadron Circular Collider (FCC-hh) to be able to detect a DM candidate within the range of masses 10-60 GeV.

hep-ph

From Peccei Quinn symmetry to mass hierarchy problem

We propose a non-universal $\mathrm{U}(1)_{X}$ gauge extension to the Standard Model (SM) and an additional Peccei-Quinn (PQ) global symmetry to study the mass hierarchy and strong CP problem. The scheme allows us to distinguish among fermion families and to generate the fermionic mass spectrum of particles of the SM. The symmetry breaking is performed by two scalar Higgs doublets and two scalar Higgs singlets, where one of these has the axion which turns out to be a candidate for Cold Dark Matter. The exotic sector is composed by one up-like $T$ and two down-like $J^{1,2}$ heavy quarks, two heavy charged leptons $E,\mathcal{E}$, one additional right-handed neutrino per family $\nu_{R}^{e,\mu,\tau}$, and an invisible axion $a$. In addition, the large energy scale associated to the breaking of the PQ-symmetry gives masses to the right-handed neutrinos in such a way that the active neutrinos acquire eV-mass values due to the see-saw mechanism. On the other hand, from the non-linear effective Lagrangian, the flavour changing of the down quarks and charged leptons with the axion are considered.

hep-ph

A $U(1)_{X}$ extension to the SM with three families and Peccei Quinn symmetry

We propose a non-universal $U(1)_{X}$ extension to the Standard Model with three families and an additional global anomala Peccei-Quinn (PQ) symmetry. The breaking of the former allows us to give masses to the exotic fermionic sector and the later generates the necessary zeros in the mass matrices to explain the fermionic mass hierarchy. In addition, the large energy scale associated with the spontaneously breaking (SSB) of the PQ symmetry provides a solution to the strong CP-problem and an axion that could be a possible dark matter candidate. Also, the SSB allows to generate right-handed neutrino masses, so the active neutrinos acquire $eV$-mass values due to the see-saw mechanism implementation.

hep-ph