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S. Penaranda

Publications and source records attributed to S. Penaranda.

At least 19 recordsLinked to original sources
arXiv2015

Discriminating between SUSY and Non-SUSY Higgs Sectors through the Ratio $H \to b \bar b / H \to τ^+ τ^-$ with a 125 GeV Higgs boson

It is still an open question whether the new scalar particle discovered at the LHC with a mass of 125 GeV is the SM Higgs boson or it belongs to models of new physics with an extended Higgs sector, as the MSSM or 2HDM. The ratio of branching fractions $R$ = BR($H \to b \bar b$)/BR($H \to τ^+ τ^-$) of Higgs boson decays is a powerful tool in order to distinguish the MSSM Higgs sector from the SM or non-supersymmetric 2HDM. This ratio receives large renormalization-scheme independent radiative corrections in supersymmetric models at large $\tanβ$, which are insensitive to the SUSY mass scale and absent in the SM or 2HDM. Making use of the current LHC data and the upcoming new results on Higgs couplings to be reported by ATLAS and CMS collaborations and in a future linear collider, we develop a detailed and updated study of this ratio $R$ which improves previous analyses and sets the level of accuracy needed to discriminate between models.

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arXiv2015

Top-quark Polarization and Asymmetries at the LHC in the Effective Description of Squark Interactions

A detailed study of top-quark polarizations and $t \bar t$ charge asymmetries, induced by top-squark-pair production at the LHC and the subsequent decays $\tilde t \to t \tilde χ_1^0$, is performed within the effective description of squark interactions, which includes the effective Yukawa couplings and another logarithmic term encoding the supersymmetry breaking. This effective approach is more suitable for its introduction into Monte-Carlo simulations and we make use of its implementation in {\tt MadGraph} in order to investigate the possibilities of the charge asymmetry $A_\text{C}$, measured at the LHC and consistent with SM expectations, to discriminate among different SUSY scenarios and analyze the implications of these scenarios in the top polarizations and related observables.

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arXiv2012

Higgs Boson masses and B-Physics Constraints in Non-Minimal Flavor Violating SUSY scenarios

We present one-loop corrections to the Higgs boson masses in the MSSM with Non-Minimal Flavor Violation. The flavor violation is generated from the hypothesis of general flavor mixing in the squark mass matrices, and these are parameterized by a complete set of delta^XY_ij (X, Y = L,R; i; j = t, c, u or b, s, d). We calculate the corrections to the Higgs masses in terms of these delta^XY_ij taking into account all relevant restrictions from B-physics data. This includes constraints from BR(B -> Xs gamma), BR(Bs -> mu+ mu-) and delta M_B_s . After taking into account these constraints we find sizable corrections to the Higgs boson masses, in the case of the lightest MSSM Higgs boson mass exceeding tens of GeV. These corrections are found mainly for the low tan beta case. In the case of a Higgs boson mass measurement these corrections might be used to set further constraints on delta^XY_ij.

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arXiv2012

Mh in the MSSM-seesaw scenario with ILC precision

We review the computation of the one-loop radiative corrections from the neutrino/ sneutrino sector to the lightest Higgs boson mass, Mh, within the context of the so-called MSSM-seesaw scenario. This model introduces right handed neutrinos and their supersymmetric partners, the sneutrinos, including Majorana mass terms. We find negative and sizeable corrections to Mh, up to -5 GeV for a large Majorana scale, 10^{13}-10^{15} GeV, and for the lightest neutrino mass in a range 0.1-1 eV. The corrections to Mh are substantially larger than the anticipated ILC precision for large regions of the MSSM-seesaw parameter space.

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arXiv2012

The Higgs sector of the NMFV MSSM at the ILC

We calculate the one-loop corrections to the Higgs boson masses within the context of the MSSM with Non-Minimal Flavor Violation in the squark sector. We take into account all the relevant restrictions from BR(B -> X_s gamma), BR(B_s -> mu^+ mu^-) and ΔM_{B_s}. We find sizable corrections to the lightest Higgs boson mass that are considerably larger than the expected ILC precision for acceptable values of the mixing parameters deltas. We find delta^{LR}_{ct} and delta^{RL}_{ct} specially relevant, mainly at low tan beta.

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arXiv2012

Heavy Majorana neutrino effects on MSSM-Mh

We study the effects of heavy Majorana neutrinos on the Higgs sector of the MSSM via radiative corrections. We work within the SUSY context where the MSSM particle content is enlarged with right handed neutrinos and their corresponding SUSY partners, the sneutrinos, and where compatibility with neutrino data is required. We compute the one-loop corrections to the mass of the lightest MSSM CP-even neutral Higgs boson from Majorana neutrinos and their SUSY partners and assume a seesaw mechanism of type I for neutrino mass generation. A negative and sizeable Higgs mass correction of up to -5 GeV is found for a heavy Majorana mass of up to 10^{15} GeV. This negative correction can grow up to several tens of GeV if the soft SUSY breaking mass associated to their sneutrino partners is simmilarly heavy as the Majorana mass.

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arXiv2011

M_h in MSSM with Heavy Majorana Neutrinos

We review the main results of the one-loop radiative corrections from the neutrino/sneutrino sector to the lightest Higgs boson mass, M_h, within the context of the so-called MSSM-seesaw scenario where right handed neutrinos and their supersymmetric partners are included in order to explain neutrino masses. For simplicity, we have restricted ourselves to the one generation case. We find sizable corrections to M_h, which are negative in the region where the Majorana scale is large (10^{13} - 10^{15} GeV) and the lightest neutrino mass is within a range inspired by data (0.1 - 1 eV). For some regions of the MSSM-seesaw parameter space, the corrections to M_h are substantially larger than the anticipated LHC precision.

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arXiv2011

Higgs Boson Masses in the MSSM with Heavy Majorana Neutrinos

We present a full diagrammatic computation of the one-loop corrections from the neutrino/sneutrino sector to the renormalized neutral CP-even Higgs boson self-energies and the lightest Higgs boson mass, Mh, within the context of the so-called MSSM-seesaw scenario. This consists of the Minimal Supersymmetric Standard Model with the addition of massive right handed Majorana neutrinos and their supersymmetric partners, and where the seesaw mechanism is used for the lightest neutrino mass generation. We explore the dependence on all the parameters involved, with particular emphasis in the role played by the heavy Majorana scale. We restrict ourselves to the case of one generation of neutrinos/sneutrinos. For the numerical part of the study, we consider a very wide range of values for all the parameters involved. We find sizeable corrections to Mh, which are negative in the region where the Majorana scale is large (10^{13}-10^{15} GeV) and the lightest neutrino mass is within a range inspired by data (0.1-1 eV). For some regions of the MSSM-seesaw parameter space, the corrections to Mh are substantially larger than the anticipated Large Hadron Collider precision.

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arXiv2009

SUSY Les Houches Accord 2

The Supersymmetry Les Houches Accord (SLHA) provides a universal set of conventions for conveying spectral and decay information for supersymmetry analysis problems in high energy physics. Here, we propose extensions of the conventions of the first SLHA to include various generalisations: the minimal supersymmetric standard model with violation of CP, R-parity, and flavour, as well as the simplest next-to-minimal model.

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arXiv2008

Collider aspects of flavour physics at high Q

This review presents flavour related issues in the production and decays of heavy states at LHC, both from the experimental side and from the theoretical side. We review top quark physics and discuss flavour aspects of several extensions of the Standard Model, such as supersymmetry, little Higgs model or models with extra dimensions. This includes discovery aspects as well as measurement of several properties of these heavy states. We also present public available computational tools related to this topic.

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arXiv2007

Flavour changing effects on e^+ e^- -> H b \bar{s}, H \bar{b} s in the MSSM

Flavour changing effects originating from the exchange of scalar particles in the processes e^+ e^- -> H b \bar{s}, H \bar{b} s, with H = h^0, H^0, A^0, are investigated in the Minimal Supersymmetric Standard Model with non-minimal flavour violation at the one-loop level. The dominating SUSY-QCD contributions with squark--gluino loops are calculated and discussed. We consider the SUSY scenario with non-minimal flavour mixing in the down-type squark-mass matrix. The flavour-changing cross sections are derived, and we discuss the dependence on the MSSM parameters and the strength of flavour mixing. The values for the cross section can reach 10^{-4} pb for the production of the heavy Higgs boson H^0 or A^0, and only 10^{-7} pb for the light Higgs boson h^0. Non-decoupling behaviour occurs for both h^0, H^0 production in the case of a common heavy SUSY mass scale.

hep-ph↗
arXiv2006

Interplay between Hbs and bsgamma in the MSSM with Non-Minimal Flavour Violation

We investigate the constraints on flavour-changing neutral heavy Higgs-boson decays H-> b \bar s from b -> s gamma bounds on the flavour-mixing parameters of the MSSM with non-minimal flavour violation (NMFV). In our analysis we include the contributions from the SM and new physics due to general flavour mixing in the squark mass matrices. We study the case of one and two non-zero flavour-mixing parameters and find that in the latter case the interference can raise the Higgs flavour-changing branching ratios by one or two orders of magnitude with respect to previous predictions based on a single non-zero parameter and in agreement with present constraints from $B$ physics. In the course of our work we developed a new "FeynArts" model file for the NMFV MSSM and added the necessary code for the evaluation to "FormCalc". Both extensions are publicly available.

hep-ph↗
arXiv2006

Les Houches "Physics at TeV Colliders 2005'' Beyond the Standard Model working group: summary report

The work contained herein constitutes a report of the "Beyond the Standard Model'' working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 2-20 May, 2005. We present reviews of current topics as well as original research carried out for the workshop. Supersymmetric and non-supersymmetric models are studied, as well as computational tools designed in order to facilitate their phenomenology.

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arXiv2005

M_W, sin^2 θ_{eff} and m_h in the NMFV MSSM

The effects of loop contributions to the electroweak precision observables and m_h in the MSSM with non-minimal flavour violation (NMFV) are analyzed, including the mixing between third and second generation squarks. The mixing-induced shift in M_W can amount to 140 MeV and to 70x10^{-5} in sin^2 θ_{eff} for extreme values of squarks mixing, allowing to set limits on the NMFV parameters. The corrections for m_h are usually small and can amount up to O(5 GeV) for large flavour violation.

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arXiv2004

Electroweak Precision Observables in the MSSM with Non-Minimal Flavor Violation

The leading corrections to electroweak precision observables in the MSSM with non-minimal flavor violation (NMFV) are calculated and the effects on M_W and sin^2 theta_eff are analyzed. The corrections are obtained by evaluating the full one-loop contributions from the third and second generation scalar quarks, including the mixing in the scalar top and charm, as well as in the scalar bottom and strange sector. Furthermore the leading corrections to the mass of the lightest MSSM Higgs boson, m_h, is obtained. The electroweak one-loop contribution to M_W can amount up to 140 MeV and up to 70x10^{-5} for sin^2 theta_eff, allowing to set limits on the NMFV parameters. The corrections for m_h are not significant for moderate generation mixing.

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arXiv2004

The Higgs Working Group: Summary Report 2003

Theoretical progress in Higgs boson production and background processes is discussed with particular emphasis on QCD corrections at and beyond next-to-leading order as well as next-to-leading order electroweak corrections. The residual theoretical uncertainties of the investigated processes are estimated in detail. Moreover, recent investigations of the MSSM Higgs sector and other extensions of the SM Higgs sector are presented. The potential of the LHC and a high-energy linear e+e- collider for the measurement of Higgs couplings is analyzed.

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arXiv2004

Determining the ratio of the H^+ -> τνto H^+ -> t b-bar decay rates for large \tanβat the Large Hadron Collider

We present results on the determination of the observable ratio R=BR(H^+ -> τν)/BR(H^+ -> t b-bar) of charged Higgs boson decay rates as a discriminant quantity between Supersymmetric and non-Supersymmetric models. Simulation of measurements of this quantity through the analysis of the charged Higgs production process gb-> t b H^+ and relative backgrounds in the two above decay channels has been performed in the context of ATLAS. A ~12-14% accuracy on R can be achieved for \tanβ=50, \mHc=300-500 GeV and after an integrated luminosity of 300 fb^-1. With this precision measurement, the Large Hadron Collider (LHC) can easily discriminate between models for the two above scenarios, so long as \tanβ> 20.

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