Searcharxiv⌕ Search

arXiv subjects

R. Noriega-Papaqui

Publications and source records attributed to R. Noriega-Papaqui.

105 records · Page 6Linked to original sources
arXiv2013

Sensitivity of the High Altitude Water Cherenkov Detector to Sources of Multi-TeV Gamma Rays

The High Altitude Water Cherenkov (HAWC) observatory is an array of large water Cherenkov detectors sensitive to gamma rays and hadronic cosmic rays in the energy band between 100 GeV and 100 TeV. The observatory will be used to measure high-energy protons and cosmic rays via detection of the energetic secondary particles reaching the ground when one of these particles interacts in the atmosphere above the detector. HAWC is under construction at a site 4100 meters above sea level on the northern slope of the volcano Sierra Negra, which is located in central Mexico at 19 degrees N latitude. It is scheduled for completion in 2014. In this paper we estimate the sensitivity of the HAWC instrument to point-like and extended sources of gamma rays. The source fluxes are modeled using both unbroken power laws and power laws with exponential cutoffs. HAWC, in one year, is sensitive to point sources with integral power-law spectra as low as 5x10^-13 cm^-2 sec^-1 above 2 TeV (approximately 50 mCrab) over 5 sr of the sky. This is a conservative estimate based on simple event parameters and is expected to improve as the data analysis techniques are refined. We discuss known TeV sources and the scientific contributions that HAWC can make to our understanding of particle acceleration in these sources.

astro-ph.HE↗
arXiv2013

Update of the 2HDM-III with a four-zero texture in the Yukawa matrices and phenomenology of the charged Higgs Boson

We update the flavor-violating constraints on the charged Higgs sector of the 2-Higgs Doublet Model Type-III (2HDM-III), using a four-zero texture in the Yukawa matrices. We give a generic Lagrangian of the 2HDM-III. In order to show the relevance of the off-diagonal terms of such a texture, we utilize the main constraints from $B$-physics, $μ-e$ universality in $τ$ decays and the radiative decay $Z\to b \bar{b}$ presented recently in arXiv:1212.6818 [hep-ph]. In particular, we show that the $H^- c \bar{b}$ coupling can be very large and very different with respect to 2HDMs with a flavor discrete symmetry (i.e., ${\mathcal{Z}}_2$). We also discuss the possible enhancements of the vertices $H^\pm W^\mp V$ ($V=Z, γ$) that arise at one-loop level.

hep-ph↗
arXiv2012

Couplings of quarks in the Partially Aligned 2HDM with a four-zero texture Yukawa matrix

The Two Higgs Doublets Model (2HDM) has provided a very useful way to describe a minimal extension of the scalar sector of the Standard Model. In this work, it is shown a scheme that we call Partial Aligned Two Higgs Doublet Model (PA-2HDM) which allows a description of the distinct versions of the 2HDM in a simple way, including those with flavor symmetries. In addition, it is shown a method to diagonalize Yukawa matrices of four-zero texture coming from the 2HDM-III. We provide some phenomenological applications in order to show the model's predictive power.

hep-ph↗
arXiv2011

On the sensitivity of the HAWC observatory to gamma-ray bursts

We present the sensitivity of HAWC to Gamma Ray Bursts (GRBs). HAWC is a very high-energy gamma-ray observatory currently under construction in Mexico at an altitude of 4100 m. It will observe atmospheric air showers via the water Cherenkov method. HAWC will consist of 300 large water tanks instrumented with 4 photomultipliers each. HAWC has two data acquisition (DAQ) systems. The main DAQ system reads out coincident signals in the tanks and reconstructs the direction and energy of individual atmospheric showers. The scaler DAQ counts the hits in each photomultiplier tube (PMT) in the detector and searches for a statistical excess over the noise of all PMTs. We show that HAWC has a realistic opportunity to observe the high-energy power law components of GRBs that extend at least up to 30 GeV, as it has been observed by Fermi LAT. The two DAQ systems have an energy threshold that is low enough to observe events similar to GRB 090510 and GRB 090902b with the characteristics observed by Fermi LAT. HAWC will provide information about the high-energy spectra of GRBs which in turn could help to understanding about e-pair attenuation in GRB jets, extragalactic background light absorption, as well as establishing the highest energy to which GRBs accelerate particles.

astro-ph.HE↗
arXiv2011

Implications of Yukawa texture in the charged Higgs boson phenomenology within 2HDM-III

We discuss the implications of assuming a four-zero Yukawa texture for the properties of the charged Higgs boson within the context of the general 2-Higgs Doublet Model of Type III. We present the charged Higgs boson couplings with heavy quarks and the resulting pattern for its decays, including the decay $H^+ \to W^+ γ$ at 1-loop level. The parameters chosen can still avoid the $B \to X_s γ$ constraint, the perturbativity and $ρ_0$ bound. Also, we present the constraints of $ B0-\bar{B}0$ mixing and of the radiative corrections to the $Z b \bar{b}$ vertex in the regime small $ \tan β$. The production of charged Higgs bosons is also sensitive to the modifications of its couplings, so that we also evaluate the resulting effects on `direct' $c\bar{b}\to H^++c. c.$ and `indirect' $q\bar q,gg\to \bar t b H^++c. c.$ production. Significant scope exists at the Large Hadron Collider for several $H^\pm$ production and decay channels combined to enable one to distinguish between such a model and alternative 2-Higgs doublet scenarios.

hep-ph↗
arXiv2010

A Numerical Analysis of the Supersymmetric Flavor Problem and Radiative Fermion Masses

We study the SUSY flavor problem in the MSSM, we are namely interested in estimating the size of the SUSY flavor problem and its dependence on the MSSM parameters. For that, we made a numerical analysis randomly generating the entries of the sfermion mass matrices and then determinated which percentage of the points are consistent with current bounds on the flavor violating transitions on lepton flavor violating (LFV) decays $l_i \to l_j γ$. We applied two methods, mass-insertion approximation method (MIAM) and full diagonalization method (FDM). Furthermore, we determined which fermion masses could be radiatively generated (through gaugino-sfermion loops) in a natural way, using those random sfermion matrices. In general, the electron mass generation can be done with 30% of points for large $\tanβ$, in both schemes the muon mass can be generated by 40% of points only when the most precise sfermion splitting (from the FDM) is taken into account.

hep-ph↗
arXiv2010

Implications of Yukawa Textures in the decay $H^+ \to W^+ γ$ within the 2HDM-III

We discuss the implications of assuming a four-zero Yukawa texture for the charged Higgs decay $H^+ \to W^+ γ$ at one-loop level, within the context of the general 2-Higgs Doublet Model of Type III. We begin by presenting a detailed analysis of the charged Higgs boson couplings with heavy quarks and the resulting effects on its decays. In particular, we present the possible enhancement of the decay $H^+ \to W^+ γ$, whose branching ratio could be of the order $\sim 10^{-1}$, for charged Higgs mass of the order 180 GeV. These parameters can still avoid the $B \to X_s γ$ constraint and the perturbativity bound. The production of charged Higgs bosons is also sensitive to the modifications of its couplings, and we evaluate the events rates at the LHC, including the `direct' $c\bar{b}\to H^++c. c.$ and `indirect' $q\bar q, gg \to \bar t b H^++c. c.$ production channels. We get an event rate of order 60 (120) for `direct' (`indirect') production reaction, and including decay $H^+ \to W^+ γ$ in the final state, with an integrated luminosity of $10^5$ $pb^{-1}$.

hep-ph↗
arXiv2009

Yukawa txtures and charged Higgs boson phenomenology in the type-III two-Higgs-doublet model

We discuss the implications of assuming a four-zero Yukawa texture for the properties of the charged Higgs boson within the context of the general 2-Higgs Doublet Model of Type III. We begin by presenting a detailed analysis of the charged Higgs boson couplings with heavy quarks and the resulting pattern for its decays. The production of charged Higgs bosons is also sensitive to the modifications of its couplings, so that we also evaluate the resulting effects on the top decay $t \to b H^{+}$ as well as on `direct' $c\bar{b}\to H^++c. c.$ and `indirect' $q\bar q,gg\to \bar t b H^++c. c.$ production. Significant scope exists at the Large Hadron Collider for several $H^\pm$ production and decay channels combined to enable one to distinguish between such a model and alternative 2-Higgs doublet scenarios.

hep-ph↗
arXiv2009

A method of diagonalization for sfermion mass matrices

We present a method of diagonalization for the sfermion mass matrices of the minimal supersymmetric standard model (MSSM). It provides analytical expressions for the masses and mixing angles of rather general hermitian sfermion mass matrices, and allows the study of scenarios that extend the usual constrained - MSSM. Three signature cases are presented explicitly and a general study of flavor changing neutral current processes is outlined in the discussion.

hep-ph↗
arXiv2007

Fundamental and composite scalars from extra dimensions

We discuss a scenario consisting of an effective 4D theory containing fundamental and composite fields. The strong dynamics sector responsible for the compositeness is assumed to be of extra dimensional origin. In the 4D effective theory the SM fermion and gauge fields are taken as fundamental fields. The scalar sector of the theory resembles a bosonic topcolor in the sense there are two scalar Higgs fields, a composite scalar field and a fundamental gauge-Higgs unification scalar. A detailed analysis of the scalar spectrum is presented in order to explore the parameter space consistent with experiment. It is found that, under the model assumptions, the acceptable parameter space is quite constrained. As a part of our phenomenological study of the model, we evaluate the branching ratio of the lightest Higgs boson and find that our model predicts a large FCNC mode h -> tc, which can be as large as O(10^{-3}). Similarly, a large BR for the top FCNC decay is obtained, namely B.R.(t -> c + H) \simeq 10^{-4}

hep-ph↗
arXiv2006

Constraints on B and Higgs Physics in Minimal Low Energy Supersymmetric Models

We study the implications of minimal flavor violating low energy supersymmetry scenarios for the search of new physics in the B and Higgs sectors at the Tevatron collider and the LHC. We show that the already stringent Tevatron bound on the decay rate B_s -> mu+ mu- sets strong constraints on the possibility of generating large corrections to the mass difference Delta M_s of the B_s eigenstates. We also show that the B_s -> mu+ mu- bound together with the constraint on the branching ratio of the rare decay b -> s gamma has strong implications for the search of light, non-standard Higgs bosons at hadron colliders. In doing this, we demonstrate that the former expressions derived for the analysis of the double penguin contributions in the Kaon sector need to be corrected by additional terms for a realistic analysis of these effects. We also study a specific non-minimal flavor violating scenario, where there are flavor changing gluino-squark-quark interactions, governed by the CKM matrix elements, and show that the B and Higgs physics constraints are similar to the ones in the minimal flavor violating case. Finally we show that, in scenarios like electroweak baryogenesis which have light stops and charginos, there may be enhanced effects on the B and K mixing parameters, without any significant effect on the rate of B_s -> mu+ mu-.

hep-ph↗
arXiv2005

Rompimiento de la Simetria Electrodebil y la Fisica del Higgs: Conceptos Basicos

Presentamos una introduccion a los conceptos basicos del rompimiento de la simetria electrodebil y la fisica del Higgs dentro del Modelo Estandar y sus extensiones supersimetricas. Se presenta tambien una breve perspectiva general de mecanismos alternativos del rompimiento de la simetria. Ademas de las bases teoricas, se discute el estado actual de la fisica experimental del Higgs y sus implicaciones para futuros experimentos en el LHC y en colisionadores lineales e+e-.

hep-ph↗
arXiv2004

Mass matrix Ansatz and lepton flavor violation in the THDM-III

Predictive Higgs-fermion couplings can be obtained when a specific texture for the fermion mass matrices is included in the general two-Higgs doublet model. We derive the form of these couplings in the charged lepton sector using a Hermitian mass matrix Ansatz with four-texture zeros. The presence of unconstrained phases in the vertices phi-li-lj modifies the pattern of flavor-violating Higgs interactions. Bounds on the model parameters are obtained from present limits on rare lepton flavor violating processes, which could be extended further by the search for the decay tau -> mu mu mu and mu-e conversion at future experiments. The signal from Higgs boson decays phi -> tau mu could be searched at the large hadron collider (LHC), while e-mu transitions could produce a detectable signal at a future e mu-collider, through the reaction e mu -> h0 -> tau tau.

hep-ph↗