arXiv subjects

R. Martinez

Publications and source records attributed to R. Martinez.

At least 55 records · Page 3Linked to original sources

arXiv2016

A predictive $331$ model with $A_{4}$ flavour symmetry

We propose a predictive model based on the $SU(3)_{C}\otimes SU(3)_{L}\otimes U(1)_{X}$ gauge group supplemented by the $A_{4}\otimes Z_{3}\otimes Z_{4}\otimes Z_{6}\otimes Z_{16}$ discrete group, which successfully describes the SM fermion mass and mixing pattern. The small active neutrino masses are generated via inverse seesaw mechanism with three very light Majorana neutrinos. The observed charged fermion mass hierarchy and quark mixing pattern are originated from the breaking of the $Z_{4}\otimes Z_{6}\otimes Z_{16}$ discrete group at very high scale. The obtained values for the physical observables for both quark and lepton sectors are in excellent agreement with the experimental data. The model predicts a vanishing leptonic Dirac CP violating phase as well as an effective Majorana neutrino mass parameter of neutrinoless double beta decay, with values $m_{ββ}=$ 2 and 48 meV for the normal and the inverted neutrino mass hierarchies, respectively.

hep-ph↗

arXiv2016

Spin-independent interferences and spin-dependent interactions with scalar dark matter

We explore mechanisms of interferences under which the spin-independent interaction in the scattering of scalar dark matter with nucleus is suppressed. We offer a detailed derivation of the nuclear amplitudes based on the interactions with quarks in the framework of a nonuniversal $U(1)'$ extension of the standard model. By assuming a range of parameters compatible with collider searches, electroweak observables and dark matter abundance, we find scenarios for destructive interferences with and without isospin symmetry. The model reveals solutions with mutually interfering scalar particles, canceling the effective spin-independent coupling with only scalar interactions, which requires an extra Higgs boson with mass $M_{H}>125$ GeV. The model also possesses scenarios with only vector interactions through two neutral gauge bosons, $Z$ and $Z'$. Due to the nonuniversality of the $U(1)'$ symmetry, we distinguish two family structures of the quark sector with different numerical predictions. In one case, we obtain cross sections that pass all the Xenon-based detector experiments. In the other case, limits from LUX experiment enclose an exclusion region for dark matter between $9$ and $800$ GeV. We examine a third scenario with isospin-violating couplings where interferences between scalar and vector boson exchanges cancel the scattering. We provide solutions where interactions with Xenon-based detectors is suppressed for light dark matter, below $6$ GeV, while interactions with Germanium- and Silicon-based detectors exhibit solutions up to the regions of interest for positive signals reported by CoGeNT and CDMS-Si experiments, and compatible with the observed DM relic density for DM mass in the range $8.3-10$ GeV. Spin-dependent interactions become the dominant source of scattering around the interference regions, where Maxwellian speed distribution is considered.

hep-ph↗

arXiv2016

Fermion mass and mixing pattern in a minimal T7 flavor 331 model

We present a model based on the $SU(3)_{C}\otimes SU(3)_{L}\otimes U(1)_{X}$ gauge symmetry having an extra $T_{7}\otimes Z_{2}\otimes Z_{3}\otimes Z_{14} $ flavor group, which successfully describes the observed SM fermion mass and mixing pattern. In this framework, the light active neutrino masses arise via double seesaw mechanism and the observed charged fermion mass and quark mixing hierarchy is a consequence of the $Z_{2}\otimes Z_{3}\otimes Z_{14}$ symmetry breaking at very high energy. In our minimal $T_{7}$ flavor 331 model, the spectrum of neutrinos includes very light active neutrinos as well as heavy and very heavy sterile neutrinos. The model has in total 16 effective free parameters, which are fitted to reproduce the experimental values of the 18 physical observables in the quark and lepton sectors. The obtained physical observables for both quark and lepton sectors are compatible with their experimental values. The model predicts the effective Majorana neutrino mass parameter of neutrinoless double beta decay to be $% m_{ββ}=$ 3 and 40 meV for the normal and the inverted neutrino spectrum, respectively. Furthermore, our model features a vanishing leptonic Dirac CP violating phase.

hep-ph↗

arXiv2015

Fermion mass and mixing pattern in a minimal T7 flavor 331 model

hep-ph↗

arXiv2015

Top quark Chromoelectric and Chromomagnetic Dipole Moments in a Two Higgs Doublet Model with CP violation

In this work we study the anomalous top quark-gluon couplings Chromoelectric Dipole Moment (CEDM) and Chromomagnetic Dipole Moment (CMDM) in a general THDM with CP violation. We find that this model provides an important contribution from the $Y_{tt}$ Yukawa coupling that needs to be taken into account. The CMDM and CEDM obtained are $-0.03<Δ\tilde{k} < 0.005}$ and $|Δ\tilde{d}| < 0.005$, respectively.

hep-ph↗

arXiv2015

Scalar coupling limits and diphoton Higgs decay from LHC in an $U(1)'$ model with scalar dark matter

In the context of an nonuniversal $U(1)'$ extension of the standard model free from anomalies, we introduce a complex scalar singlet candidate to be dark matter. In addition, an extra scalar doublet and a heavy scalar singlet are required to provide masses to all fermions and to break spontaneously the symmetries. From unitarity and stability of the Higgs potential, we find the full set of bounds and order relations for the scalar coupling constants. Using recent data from the CERN-LHC collider, we study the signal strenght of the diphoton Higgs decay $R_{γγ}$, which imposes very stringent bounds to the scalar couplings and other scalar parameters. We obtain constraints in different scenarios of the space of parameters, where decays into dark matter may or may not contribute according to the mass of the scalar dark matter candidate. By assuming that the lightest scalar boson of the model corresponds to the observed Higgs boson, we evaluate deviations from the SM of the trilineal Higgs self-coupling. The conditions from unitarity, stability and Higgs diphoton decay data allow trilineal deviations in the range $0 \leq δg \lesssim -72\%$.

hep-ph↗

arXiv2015

$S_3$ discrete group as a source of the quark mass and mixing pattern in $331$ models

We propose a model based on the $SU(3)_{C}\otimes SU(3)_{L}\otimes U(1)_{X}$ gauge symmetry with an extra $S_{3}\otimes Z_{2}\otimes Z_{4}\otimes Z_{12}$ discrete group, which successfully accounts for the SM quark mass and mixing pattern. The observed hierarchy of the SM quark masses and quark mixing matrix elements arises from the $Z_{4}$ and $Z_{12}$ symmetries, which are broken at very high scale by the $SU(3)_{L}$ scalar singlets ($σ$,$ζ$) and $τ$, charged under these symmetries, respectively. The Cabbibo mixing arises from the down type quark sector whereas the up quark sector generates the remaining quark mixing angles. The obtained magnitudes of the CKM matrix elements, the CP violating phase and the Jarlskog invariant are in agreement with the experimental data.

hep-ph↗

arXiv2014

Connection of $g-2_μ$, electroweak, dark matter, and collider constraints on 331 models

In this work we compute all contributions to the muon magnetic moment stemming from several 3-3-1 models namely, minimal 331, 331 with right handed neutrinos, 331 with heavy neutral leptons, 331 with charged exotic leptons, 331 economical and 331 with two higgs triplets. Further, we exploit the complementarity among current electroweak, dark matter and collider constraints to outline the relevant parameter space of the models capable of explaining the anomaly. Lastly, assuming that the experimental anomaly has been otherwise resolved, we derive robust $1σ$ bounds using the current and projected measurements.

hep-ph↗

arXiv2014

Lepton masses and mixing in $SU(3)_{C}\otimes SU(3)_{L}\otimes U(1)_{X}$ models with a $S_3$ flavor symmetry

We propose a model based on the gauge group $SU(3)_{C}\otimes SU(3)_{L}\otimes U(1)_{X}$ with an extra $S_{3}$ flavor symmetry, which accounts for the lepton masses and mixing. The small active neutrino masses are generated via a double seesaw mechanism. In this scenario, the spectrum of neutrinos presents very light, light and very heavy masses. The model predicts a quasidegenerate normal hierarchy active neutrino mass spectrum and the relation $Δm_{21}^{2}\ll Δm_{31}^{2}$ arises from effective six-dimensional operators. The obtained neutrino mixing parameters are in agreement with the neutrino oscillation experimental data. We find CP violation in neutrino oscillations with a Jarlskog invariant of about $10^{-2}$.

hep-ph↗

arXiv2014

Scalar Dark Matter with CERN-LEP data and $Z'$ search at the LHC in an $U(1)'$ Model

In the framework of an nonuniversal $U(1)'$ extension of the standard model, we propose an scalar candidate for cold dark matter which exhibits interactions with ordinary matter through Higgs and gauge bosons. Using limits from low energy observables, we find constraints on the new physics parameters of the model associated to the extra abelian symmetry, in particular, the mass of the additional neutral gauge boson $Z'$ and the new gauge coupling constant. We found that for the lower experimental limit $M_{Z'}=3$ TeV constrained by direct research at LHC, the ratio between the $U(1)'$ and $SU(2)_L$ gauge coupling constants is around $0.4$. Taking into account this limit and the observable relic density of the Universe, we search for new constraints on the mass of the dark matter particle of the model. We found that for a higgsphobic model, the mass of the scalar dark matter must be $M_σ=70$ GeV. We also found different kinematical threshold and resonances that enhance the dispersion of dark matter into ordinary matter for different regions of the space of parameters of the model, obtaining masses as low as $1.3$ GeV and as large as $125$ GeV with not allowed intermediate regions due to resonances.

hep-ph↗

arXiv2014

Rare top decay $t\rightarrow cγ$ in general THDM-III

We study the decay $t\rightarrow cγ$ with flavor-changing neutral interactions in scalar sector of the type III Two Higgs Doublet Model (THDM-III) with mixing between neutral scalar fields as a result of considering the most general scalar potential. The branching ratio of the decay $Br(t\rightarrow cγ)$ is calculated as function of the mixing parameters and masses of the neutral scalar fields. We obtain a $Br(t\rightarrow cγ)$ of the order of $10^{-8}$ for the considered regions of the mixing parameters. Finally, one upper bound for the possible events is estimated to be $n=18$ by assuming a expected luminosity of the order of 300 $fb^{-1}$.

hep-ph↗

arXiv2014

Constraints on 3-3-1 models with electroweak Z pole observables and Z' search at LHC

In the framework of general 3-3-1 models, we perform a global $χ^2$ fit at $95\%$ C.L. to the updated Z pole observables, including new data from atomic parity violation. We found scenarios where specific realizations of 3-3-1 models are largely excluded above the current limit on the extra neutral gauge boson ($Z'$) research at LHC. We derive a relation between the $Z-Z'$ mixing angle and the parameter $\tan(β)$ of the effective Two-Higgs-Doublet Model contained into the 3-3-1 spectrum. We show that particular versions of 3-3-1 models containing particles with exotic electric charges are disfavored by the electroweak precision observables in an ample region of the parameter space.

hep-ph↗

arXiv2014

Some phenomenological aspects of a new $U(1)'$ model

We propose a new non-universal $U(1)'$ extension of the standard model with the addition of three exotic quark singlets, two scalar singlets and one additional scalar doublet. We obtain family dependent couplings with a new $Z'$ boson in the quark sector and universal couplings with the lepton sector. From experimental data on $Z'$ research at CERN-LHC collider, we find limit regions in the $U(1)'$ free parameters ($Z'$ mass and coupling constant), which we use to obtain total decay width and invariant-mass distributions. By introducing discrete symmetries and mixing couplings between ordinary and exotic fermions, we obtain predictable mass relations in the quark sector compatible with the phenomenological values without large fine tuning of the Yukawa couplings and with few free parameters, where hierarchies between quark families can be understood from the existence of heavy beyond standard model particles.

hep-ph↗

arXiv2013

Rare top decay and CP violation in THDM

We discuss the formalism of two Higgs doublet model type III with CP violation from CP-even CP-odd mixing in the neutral Higgs bosons. The flavor changing interactions among neutral Higgs bosons and fermions are presented at tree level in this type of model. These assumptions allow the study rare top decays mediated by neutral Higgs bosons, particularly we are interested in $t\rightarrow c l^+l^-$. For this process we estimated upper bounds of the branching ratios $\textrm{Br}(t\rightarrow c τ^+τ^-)$ of the order of $10^{-9}\sim 10^{-7}$ for a neutral Higgs boson mass of 125 GeV and $\tanβ=1$, 1.5, 2, 2.5. For the case of $t\rightarrow c τ^+τ^-$ the number of possible events is estimated from 1 to 10 events which could be observed in future experiments at LHC with a luminosity of 300 $\textrm{fb}^{-1}$ and 14 GeV for the energy of the center of mass. Also we estimate that the number of events for the process $t\rightarrow c l^+l^-$ in different scenarios is of order of $2500$.

hep-ph↗

arXiv2013

Operational experience, improvements, and performance of the CDF Run II silicon vertex detector

The Collider Detector at Fermilab (CDF) pursues a broad physics program at Fermilab's Tevatron collider. Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron delivered 12 fb-1 of integrated luminosity of p-pbar collisions at sqrt(s)=1.96 TeV. Many physics analyses undertaken by CDF require heavy flavor tagging with large charged particle tracking acceptance. To realize these goals, in 2001 CDF installed eight layers of silicon microstrip detectors around its interaction region. These detectors were designed for 2--5 years of operation, radiation doses up to 2 Mrad (0.02 Gy), and were expected to be replaced in 2004. The sensors were not replaced, and the Tevatron run was extended for several years beyond its design, exposing the sensors and electronics to much higher radiation doses than anticipated. In this paper we describe the operational challenges encountered over the past 10 years of running the CDF silicon detectors, the preventive measures undertaken, and the improvements made along the way to ensure their optimal performance for collecting high quality physics data. In addition, we describe the quantities and methods used to monitor radiation damage in the sensors for optimal performance and summarize the detector performance quantities important to CDF's physics program, including vertex resolution, heavy flavor tagging, and silicon vertex trigger performance.

physics.ins-det↗

arXiv2012

Production of multiple charged Higgs bosons in 3-3-1 models

We undertake the study of the charged Higgs bosons predicted by the model with gauge symmetry $SU(3)_c \otimes SU(3)_L \otimes U(1)_X$. By considering Yukawa mixing couplings between small ($\sim$ GeV) and large ($\sim$ TeV) scales, we show that the hypercharge-one $H_1^{\pm}$ and hypercharge-two $H_2^{\pm}$ Higgs bosons predicted by the model, can be simultaneously produced in $pp$ collisions at different production rates. At low energy, the $H_1^{\pm}$ bosons exhibit the same properties as the charged Higgs bosons from a two Higgs doublet model (2HDM), while $H_2^{\pm}$ are additional like-charged Higgs bosons from the underlying 3-3-1 model. Thus, the identification of multiple like-charged Higgs boson resonances may test the compatibility of theoretical models with experimental data. We study $H_{1,2}^{\pm}$ pair and associated $tbH_{1,2}^{\pm}$ productions at CERN LHC collider. In particular, we obtain that pair production can be as large as the single production in gluon-gluon collisions due to the interchange of a heavy neutral $Z'$ gauge boson predicted by the model. By considering decays to leptons $H_{1,2}^{\pm} \rightarrow τν_τ$, we obtain scenarios where small peaks of $H_{2}^{\pm}$-boson events in transverse mass distributions can be identified over the $H_{1}^{\pm}$ background.

hep-ph↗

arXiv2012

The Richardson's Annular effect and a transient solution of oscillating pressure-driven flow in circular pipes

In this paper it is shown that the location of the characteristic overshoot of the Richardson's annular effect changes with the Kinematic Reynolds number $ω^*=ωr_0^2 /ν$ in the range of frequencies within the laminar regime. From the study of the Richardson's overshoot at different times it was identified the existence of aparent transverse damped waves similar to those ones observed in the famous Stokes second problem, the physical analysis of this waves was used for the establishment of a semi-empirical law that gives the functional relation of the mean overshoot maximum with the kinematic reynolds number, say $B_0(ω^*)=2.28 + 0.51{ω^*}^{-1/2}$. Finally a transient solution was constructed and verified asymptotically for large times, and the tipical time for which the transient solution resembles the steady oscillating one was identified to be dependent of the viscosity of the fluid and of the radius of the pipe.

physics.flu-dyn↗

arXiv2012

Quark mass hierarchy in 3-3-1 models

We study the mass spectrum of the quark sector in an special type I-like model with gauge symmetry $SU(3)_c \otimes SU(3)_L \otimes U(1)_X$. By considering couplings with scalar triplets at large ($\sim TeV$) and small ($\sim GeV$) scales, we obtain specific zero-texture mass matrices for the quarks which predict three massless quarks ($u,d,s$) and three massive quarks ($c,b,t$) at the electroweak scale ($\sim$ GeV). Taking into account mixing couplings with three heavy quarks at large scales predicted by the model, the three massless quarks obtain masses at small order that depends on the inverse of the large scale. Thus, masses of the form $m_u \lesssim m_d < m_s \sim MeV$ and $ m_{c,b,t} \sim GeV$ can be obtained naturally from the gauge structure of the model.

hep-ph↗