J. Lorenzo Diaz-Cruz

Meritorious Autonomous University of Puebla, Puebla, Estado de Baja California, Mexico

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Publications (96)176.95 Total impact

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    Nestor Quintero, J. Lorenzo Diaz-Cruz, Gabriel Lopez Castro
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    ABSTRACT: The general two-higgs doublet model (2HDM) contains a rich spectrum of neutral and charged Higgs bosons, whose detection would be a clear signal of new physics. When the Higgs potential is CP-conserving, the spectrum includes a pseudoscalar mass eigenstate $A^{0}$, which does not couple to vector bosons at tree-level. However, fermionic loops (top and bottom mainly) induce the coupling $AVV'$ (with $V,V'=\gamma, Z$) at higher orders. We evaluate the amplitude for the decays ${A^0} \to ZZ, Z\gamma, \gamma\gamma$, including a generic fermionic loop contribution, and present results on the branching ratios for 2HDM-I,II and III. Current LHC searches on heavy Higgs bosons are used as an estimate to constrain the allowed mass range for $A^0$.
    03/2014;
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    Nestor Quintero, J. Lorenzo Diaz-Cruz, Gabriel Lopez Castro
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    ABSTRACT: The heaviness of the top quark makes its 2-body decay mode $t \to bW^+$ to be dominant, at such level that hardly any other decay mode reaches a detectable branching ratio (BR) within the SM. Here we study the decay $t \to bW^+\ell^-\ell^+$ ($\ell=e, \mu, \tau$), which diverges for massless leptons, and it can reach a BR $\sim \mathcal{O}(10^{-5}\sim 10^{-6})$ for reasonable values of the low energy cut in the lepton-pair invariant mass. This rate surpasses almost any other rare decays such as $t \to cX$ ($X=\gamma,Z,g,H, W^+W^-$), and thus offers the possibility of being detectable. Furthermore, the estimate of this channel is relevant because it can mimic the signal arising from the lepton number violating decay $t\to bW^-\ell^+\ell^+$, when the $W$ boson decays into lepton channels.
    03/2014;
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    ABSTRACT: We study the phenomena of flavor violation, and its implications for Higgs signals, within the context of the Two-Higgs doublet model with Textures (2HDM-Tx). Unlike previous works, where the set of Yukawa matrices are assumed to have the same form (parallel textures), we study combinations of Yukawa matrices with different textures (complementary textures) that produce a hermitian mass matrix with a specific four-zero texture type. In this case, the size of Flavor Violation depends on the parameters tan beta(= v_2/v_1) and gamma (0 < gamma < 1), that appears in the relation between the top mass and the 33 entry of the mass matrix. We find that in order to satisfy current experimental bounds from K-K mixing, B_s -> mu^+ mu^- and tau -> mu mu mu, only restricted values of gamma and tan beta are allowed. Furthermore, we also study the constraints that arise from imposing current LHC bounds on the Higgs boson couplings. The predictions of our study include the Flavor Violating decays (h -> tau mu) and t -> c h, which reach Branching ratios that could be tested at the LHC in the coming era of precision Flavor Higgs physics.
    06/2013;
  • Ernesto Arganda, J. Lorenzo Diaz-Cruz, Alejandro Szynkman
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    ABSTRACT: The recent discovery of a new boson at the LHC, which resembles a SM-like Higgs boson with m h =125 GeV, is starting to provide strong guidelines into SUSY model building. For instance, the identification of such a state with the lightest CP-even Higgs boson of the MSSM ( h 0), requires large values of tan β and/or heavy sfermions. One outcome of this result is the possibility to solve the SUSY flavor and CP problems by decoupling, which points towards some realization of Split-inspired SUSY scenarios, in which scalars are much heavier than gauginos and higgsinos. However, we argue here that the remaining Higgs bosons of the MSSM ( H 0, A 0, H ±) do not have to be as heavy as the sfermions, and having them with masses near the EW scale does not pose any conflict with current MSSM constraints. We discuss then some SUSY scenarios with heavy sfermions, from a bottom-up approach, which contain the full Higgs sector, as well as a possible dark matter candidate, with masses near the EW scale, and identify distinctive signals from these scenarios that could be searched at the LHC.
    European Physical Journal C 04/2013; · 5.25 Impact Factor
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    ABSTRACT: Models with extra gauge bosons often require an extended Higgs sector, which contains a rich spectrum of Higgs bosons with properties that deviate from the Standard Model (SM). Such Higgs bosons could be searched using standard mechanisms similar to the SM. However, the existence of the new gauge bosons could provide new production mechanisms, which could probe the non-standard origin of the Higgs particle. In this paper we study how the Z' from a model with extra U(1)' could be used as a source of Higgs bosons. We study 3-bodies decays of the Z' into a Higgs boson and a top anti-top pair or WW pair, namely Z'\to t\bar{t} h, WW h. We find that it is possible to get {\Br'}s as high as 10^{-2} for these modes, which could be studied at future colliders. We also study the production of the Higgs bosons in association with the Z vector boson at a linear collider, through the reaction e^+ e^- \to Z, Z'\to Z+h, including both the resonant and the non-resonant effects.
    Journal of Physics G Nuclear and Particle Physics 03/2013; 40(12). · 5.33 Impact Factor
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    ABSTRACT: The ATLAS and CMS collaborations have observed independently a new Higgs-like particle with a mass $M_h \sim$ 125 GeV. It is of great interest nowadays to understand the origin and identity of such a particle, whether it comes from the Standard Model (SM) or from some extension of it, such as Supersymmetry (SUSY).The simplest SUSY extension of the SM, the so-called Minimal Supersymmetric Standard Model (MSSM), predicts the tree-level mass relation $M_h\leq M_Z$, so that significant radiative corrections, coming from heavy stop masses and/or large values of $\tan\beta$, are required in order to reach a 125 GeV Higgs boson mass, as well known. Literature already exists within the MSSM also for the case of attempting to explain other ATLAS and CMS results, in particular, an apparent excess in the $gg$-induced $\gamma\gamma$ channel, over and above the SM predictions in presence of a Higgs boson. Here, we are interested in evaluating the modifications on these (CP-conserving) MSSM results that appear within the CP-violating version of the MSSM. Namely, we will evaluate the role of the complex phases of the soft SUSY terms and the $\mu$ parameter on both the mass of the light Higgs boson, $h_1$, and their effects on the rates for the process $gg \rightarrow h_1 \rightarrow \gamma \gamma$.
    01/2013;
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    Article: Slim SUSY
    Ernesto Arganda, J. Lorenzo Diaz-Cruz, Alejandro Szynkman
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    ABSTRACT: The new SM-like Higgs boson discovered recently at the LHC, with mass $m_h \simeq$ 125 GeV, as well as the direct LHC bounds on the mass of superpartners, which are entering into the TeV range, suggest that the minimal surviving supersymmetric extension of the SM (MSSM), should be characterized by a heavy SUSY-breaking scale. Several variants of the MSSM have been proposed to account for this result, which vary according to the accepted degree of fine-tuning. We propose an alternative scenario here, Slim SUSY, which contains sfermions with multi-TeV masses and gauginos/higgsinos near the EW scale, but it includes the heavy MSSM Higgs bosons ($H^0$, $A^0$, $H^\pm$) near the EW scale too. We discuss first the formulation and constraints of the Slim SUSY scenario, and then identify distinctive heavy Higgs signals that could be searched at the LHC, within scenarios with the minimal number of superpartners with masses near the EW scale.
    01/2013;
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    Ernesto Arganda, J. Lorenzo Diaz-Cruz, Alejandro Szynkman
    [Show abstract] [Hide abstract]
    ABSTRACT: The recent discovery of a new boson at the LHC, which resembles a SM-like Higgs boson with $m_h=125$ GeV, is starting to provide strong guidelines into SUSY model building. For instance, the identification of such a state with the lightest CP-even Higgs boson of the MSSM ($h^0$), requires large values of $\tan\beta$ and/or heavy sfermions. One outcome of this result is the possibility to solve the SUSY flavor and CP problems by decoupling, which points towards some realization of the Split SUSY scenario, in which scalars are much heavier than gauginos and higgsinos. However, we argue here that the remmaining Higgs bosons of the MSSM ($H^0$, $A^0$, $H^{\pm}$) do not have to be as heavy as the sfermions, and having them with masses near the EW scale does not pose any conflict with current MSSM constraints. We discuss then some variants of Split SUSY models that contain the full Higgs sector, as well as a possible DM candidate, with masses near the EW scale, and identify distinctive signals from these scenarios that could be searched at the LHC.
    11/2012;
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    Alfredo Aranda, Cesar Bonilla, J. Lorenzo Diaz-Cruz
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    ABSTRACT: Multi Higgs doublet models are interesting extensions of the Standard Model that can be related to flavor. The reason is that most flavor models usually involve the presence of several additional scalar fields. In this work we present an analysis that shows that for renormalizable flavor models based on the cyclic group of order $N$, if there is one flavored SU(2) double Higgs per generation, the smallest $N$ that can be used to reproduce the Nearest-Neighbor-Interaction texture for the quark mass matrices is N=5. Results for the Higgs spectrum and consistency under $K - \bar{K}$ mixing in a specific model with $Z_5$ are also presented.
    Physics Letters B 04/2012; 717(s 1–3). · 4.57 Impact Factor
  • A.aranda, J. L.dÍaz-cruz, A.rosado
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    ABSTRACT: We propose an alternative unification scenario where the Higgs self-coupling (λ) is determined by imposing its unification with the electroweak gauge couplings. An attractive feature of models within this scenario is the possibility to determine the Higgs boson mass by evolving λ from the electroweak–Higgs unification scale MGH down to the electroweak scale. The unification condition for the gauge (g1, g2) and Higgs couplings is written as g1 = g2 = f(λ), where being the normalization constant. Two variants for the unification condition are discussed; scenario I is defined through the linear relation: g1 = g2 = kHλ(MGH), while scenario II assumes a quadratic relation: . Fixing kH = O(1) and the standard normalization (kY = 5/3), we obtain a Higgs boson mass value mH ≃ 190 GeV, with similar results for other normalizations such as kY = 7/4 and 3/2. However, the unification scale MGH depends on the value of kY, going from 1.8 ×1012GeV up to 4.9 ×1014GeV for 7/4 > kY > 3/2. Possible tests of this idea at a future linear collider and its application for determining the Higgs spectrum in the two-Higgs doublet model are also discussed. We also elaborate on these unification scenarios within the context of a six-dimensional SU(3)c×SU(3)w Gauge–Higgs unified model, where the Higgs boson arises as the extra-dimensional components of the 6D gauge fields.
    International Journal of Modern Physics A 01/2012; 22(07). · 1.13 Impact Factor
  • Alfredo Aranda, J. L. Díaz-Cruz, Alma D. Rojas
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    ABSTRACT: The minimal Higgs sectors of Supersymmetric Grand Unified Theories (SGUT's) can be extended by introducing higher dimensional (anomaly free) representations. We have found models with different anomaly free combinations of SU(5) representations which are different in terms or their &pbeta; functions. It is also interesting to consider the RGE effect associated with the Yukawa coupling that involve the additional Higgs representations. In order to do this we shall consider the 2-loop &pbeta; functions for the gauge coupling, but will keep only the 1-loop RGE for the new Yukawa couplings, in a SU(5) SGUT model.
    09/2011;
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    ABSTRACT: A model based on SU(3)_C X SU(2)_L X U(1)_Y X SU(2)_N has recently been proposed, where the SU(2)_N vector gauge bosons are neutral, so that a vector dark-matter candidate is possible and constrained by data to be less than about 1 TeV. We explore further implications of this model, including a detailed study of its Higgs sector. We improve on its dark-matter phenomenology, as well as its discovery reach at the LHC (Large Hadron Collider).
    Physical review D: Particles and fields 07/2011;
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    Alfredo Aranda, J. Lorenzo Diaz-Cruz, Alfonso Rosado
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    ABSTRACT: A scenario is presented where the $s$, $c$, and $b$ quark fusion Higgs production cross sections are enhanced with respect to those of the Standard Model. In particular the $c$ quark fusion production is very important and can account for a significant contribution at the Large Hadron Collider. The light Higgs couplings to vector bosons are sufficiently suppressed to allow its mass to lie below the LEP bound of 115 GeV and due to enhanced couplings to second family fermions, the Higgs decay to $\mu$ pairs is large enough to be detectable. This is accomplished with a model incorporating three Higgs doublets charged under a flavor symmetry.
    07/2011;
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    J. Lorenzo Diaz-Cruz, Ernest Ma
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    ABSTRACT: If the standard model of particle interactions is extended to include a neutral SUN(2) gauge factor, with SUC(3)×SUL(2)×UY(1)×SUN(2) embedded in E6 or 3[SU(3)], a conserved generalized R parity may appear. As a result, apart from the recent postulate of a separate non-Abelian gauge factor in the hidden sector, we have the first example of a possible dark-matter candidate X1 which is a non-Abelian vector boson coming from a known unified model. Using current data, its mass is predicted to be less than about 1 TeV. The associated Z′ of this model, as well as some signatures of the Higgs sector, should then be observable at the LHC (Large Hadron Collider).
    Physics Letters B 01/2011; · 4.57 Impact Factor
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    Jose A. R. Cembranos, J. Lorenzo Díaz-Cruz, Lilian Prado
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    ABSTRACT: Dark Matter direct detection experiments are able to exclude interesting parameter space regions of particle models which predict an important amount of thermal relics. We use recent data to constrain the branon model and to compute the region that is favored by CDMS measurements. Within this work, we also update present colliders constraints with new studies coming from the LHC. Despite the present low luminosity, it is remarkable that for heavy branons, CMS and ATLAS measurements are already more constraining than previous analyses performed with TEVATRON and LEP data.
    Physical review D: Particles and fields 01/2011; 84.
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    Alfredo Aranda, J. L. Diaz-Cruz, Alma D. Rojas
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    ABSTRACT: Supersymmetric Grand Unified Theories (SGUTs) have achieved some degree of success, already present in the minimal models (with SU(5) or SO(10)). However, there are open problems that suggest the need to incorporate more elaborate constructions, specifically the use of higher-dimensional representations in the Higgs sector. For example, a $45$ representation of SU(5) is often included to obtain correct mass relations for the first and second families of d-type quarks and leptons. When one adds these higher-dimensional Higgs representations one must verify the cancellation of anomalies associated to their fermionic partners. One possible choice, free of anomalies, include both $45,\overline{45}$ representations to cancel anomalies. We review the necessary conditions for the cancellation of anomalies and discuss the different possibilities for supersymmetric SU(5) models. Alternative anomaly-free combinations of Higgs representations, beyond the usual vectorlike choice, are identified, and it is shown that their corresponding $\beta$ functions are not equivalent. Although the unification of gauge couplings is not affected, the introduction of multidimensional representations leads to different scenarios for the perturbative validity of the theory up to the Planck scale. We study the effect on the evolution of the gauge coupling up to the Planck scale due to the different sets of fields and representations that can render an anomaly-free model.
    Journal of Physics Conference Series 08/2010; 315(1).
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    ABSTRACT: We explore in detail the Higgs phenomenology that results in a model where right-handed neutrinos have a mass scale of the order of the electroweak scale. In this model all scales arise from spontaneous symmetry breaking, and this is achieved with a Higgs sector that includes an extra Higgs singlet in addition to the standard model Higgs doublet. The scalar spectrum includes two neutral CP-even states ($h$ and $H$ with $m_{h} < m_{H}$)and a neutral CP-odd state ($\sigma$) that can be identified as a pseudo-Majoron. The parameter of the Higgs potential are constrained using a perturbativity criteria. Higgs BR and cross-sections are discussed, with special emphasis on the detection at the LHC.
    International Journal of Modern Physics A 07/2010; 26. · 1.13 Impact Factor
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    ABSTRACT: In the recently proposed dark left-right gauge model of particle interactions, the left-handed fermion doublet $(\nu,e)_L$ is connected to its right-handed counterpart $(n,e)_R$ through a scalar bidoublet, but $\nu_L$ couples to $n_R$ only through $\phi_1^0$ which has no vacuum expectation value. The usual R parity, i.e. $R = (-)^{3B+L+2j}$, can be defined for this nonsupersymmetric model so that both $n$ and $\Phi_1$ are odd together with $W_R^\pm$. The lightest $n$ is thus a viable dark-matter candidate (scotino). Here we explore the phenomenology associated with the $SU(2)_R$ gauge group of this model, which allows it to appear at the TeV energy scale. The exciting possibility of $Z' \to 8$ charged leptons is discussed. Comment: 12 pages, 2 figures
    Physical Review D 01/2010; 81(075010). · 4.69 Impact Factor
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    ABSTRACT: The asymmetric Higgs sector of one SU(2)L×SU(2)R bidoublet (ϕ10,ϕ1-;ϕ2+,ϕ20) and one SU(2)R doublet [but no SU(2)L doublet] is considered in a nonsupersymmetric left-right extension of the standard model of particle interactions. The inverse seesaw mechanism for neutrino mass is naturally implemented with the addition of fermion singlets, allowing thereby the possibility of breaking SU(2)R at the TeV scale. Flavor-changing neutral Higgs couplings to quarks are studied in two scenarios, where the SU(2)R charged-current mixing matrix is given either by the Cabibbo-Kobayashi-Maskawa matrixVR=VCKM (scenario I) or VR=1 (scenario II). We consider the bounds on these scalar particle masses from K-K̅ and B-B̅ mixing, as well as b→sγ. We find that, whereas in scenario I, they are of order 10 TeV, as in other left-right models, they may be well below 1 TeV in scenario II, thus allowing them to be within reach of detection at the forthcoming Large Hadron Collider.
    Phys. Rev. D. 12/2009; 80(11).

Publication Stats

791 Citations
176.95 Total Impact Points

Institutions

  • 1998–2011
    • Meritorious Autonomous University of Puebla
      • Facultad de Ciencias Físico Matemáticas
      Puebla, Estado de Baja California, Mexico
  • 2006–2010
    • Universidad de Colima
      • Faculty of Science
      Colima, Colima, Mexico
  • 2003–2008
    • University of Southampton
      • Department of Physics and Astronomy
      Southampton, England, United Kingdom
    • Boston University
      • Department of Physics
      Boston, Massachusetts, United States
  • 2001
    • University of Texas at Austin
      • Department of Physics
      Austin, Texas, United States
  • 2000
    • Lawrence Berkeley National Laboratory
      Berkeley, California, United States
  • 1993
    • Universidad Autónoma de Madrid
      • Department of Theoretical physics
      Madrid, Madrid, Spain
  • 1992
    • Autonomous University of Barcelona
      Cerdanyola del Vallès, Catalonia, Spain