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M. J. Herrero

Publications and source records attributed to M. J. Herrero.

At least 55 records · Page 3Linked to original sources
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

Sensitivity to the Higgs Sector of SUSY-Seesaw Models in the Lepton Flavour Violating tau-->mu f0(980) decay

In this work we study the Lepton Flavour Violating semileptonic tau --> mu f0(980) decay within the context of SUSY-Seesaw Models, where the MSSM spectrum is extended by three right handed neutrinos and their SUSY partners, and where the seesaw mechanism is used to generate the neutrino masses. We estimate its decay rate when it proceeds via the Higgs mediated channel tau --> mu H* --> mu f0(980), where H refers to the CP-even MSSM Higgs bosons h^0 and H^0, and the Lepton Flavour Violating tau mu H vertex is radiatively generated via SUSY loops. In order to describe the f0(980) meson we follow the guidelines from chiral constraints. As an implication of our computation, we explore the sensitivity to the Higgs sector in this decay and compare it with other LFV tau decay channels. The confrontation of our predictions for BR(tau --> mu f0(980)) with its very competitive present experimental bound leads us to extract some interesting restrictions on the most relevant model parameters, particularly, tanbeta and m_{H^0}.

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arXiv2008

Lepton flavour violation in constrained MSSM-seesaw models

We calculate the predictions for lepton flavour violating (LFV) tau and muon decays, $l_j \to l_i γ$, $l_j \to 3 l_i$, $μ-e$ conversion in nuclei and LFV semileptonic tau decays $τ\to μPP$ with $PP= π^+π^-, π^0π^0, K^+K^-, K^0 {\bar K}^0$ $τ\to μP$ with $P=π^0, η, η'$ and $τ\to μV$ with $V = ρ^0, ϕ$, performing the hadronisation of quark bilinears within the chiral framework. We work within a SUSY-seesaw context where the particle content of the Minimal Supersymmetric Standard Model is extended by three right-handed neutrinos plus their corresponding SUSY partners, and where a seesaw mechanism for neutrino mass generation is implemented. Two different scenarios with either universal or non-universal soft supersymmetry breaking Higgs masses at the gauge coupling unification scale are considered. After comparing the predictions with present experimental bounds and future sensitivities, the most promising processes are particularly emphasised.

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arXiv2008

LFV in semileptonic $τ$ decays and $μ-e$ conversion in nuclei in SUSY-seesaw

Here we review the main results of LFV in the semileptonic tau decays $τ\to μPP$ ($PP = π^+ π^-, π^0 π^0, K^+ K^-, K^0 \bar{K}^0$), $τ\to μP$ ($P = π, η, η^{\prime}$), and $τ\to μV$ ($V = ρ, ϕ$) as well as in $μ-e$ conversion in nuclei within SUSY-seesaw scenarios, and compare our predictions with the present experimental bounds

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arXiv2008

Lepton flavour violating semileptonic tau decays in constrained MSSM-seesaw scenarios

In this work we study the Lepton Flavour Violating semileptonic $τ$ decays: 1) $τ\to μPP$ with $PP= π^+π^-, π^0π^0, K^+K^-, K^0 {\bar K}^0$; 2) $τ\to μP$ with $P=π^0, η, η'$ and 3) $τ\to μV$ with $V = ρ^0, ϕ$. We work within the context of two constrained MSSM scenarios: the CMSSM and NUHM. A full one-(SUSY)loop computation is presented and the importance of the various contributions, the $γ$-, $Z$-, and Higgs bosons mediated ones are analysed. The hadronization of quark bilinears is performed within the chiral framework. Some discrepancies in the predicted rates for BR($τ\to μη$), BR($τ\to μη'$) and BR($τ\to μK^+K^-$) are found with respect to previous estimates, which will be commented here. These three channels will be shown to be the most competitive ones to test simultaneously the Lepton Flavour Violation and the Higgs sector. We further present here a set of approximate formulas for all the semileptonic channels which we believe can be useful for further comparison with present and future data.

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arXiv2008

Flavour physics of leptons and dipole moments

This chapter of the report of the ``Flavour in the era of the LHC'' Workshop discusses the theoretical, phenomenological and experimental issues related to flavour phenomena in the charged lepton sector and in flavour-conserving CP-violating processes. We review the current experimental limits and the main theoretical models for the flavour structure of fundamental particles. We analyze the phenomenological consequences of the available data, setting constraints on explicit models beyond the Standard Model, presenting benchmarks for the discovery potential of forthcoming measurements both at the LHC and at low energy, and exploring options for possible future experiments.

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arXiv2007

Lepton Flavour Violation in SUSY-seesaw: an update

Here we update the predictions for lepton flavour violating tau and muon decays, $l_j \to l_i γ$, $l_j \to 3 l_i$, and $μ-e$ conversion in nuclei. We work within a SUSY-seesaw context where the particle content of the Minimal Supersymmetric Standard Model is extended by three right handed neutrinos plus their corresponding SUSY partners, and where a seesaw mechanism for neutrino mass generation is implemented. Two different scenarios with either universal or non-universal soft supersymmetry breaking Higgs masses at the gauge coupling unification scale are considered. After comparing the predictions with present experimental bounds and future sensitivities, the most promising processes are particularly emphasised.

hep-ph↗
arXiv2007

$μ-e$ conversion in nuclei within the CMSSM seesaw: universality versus non-universality

In this paper we study $μ-e$ conversion in nuclei within the context of the Constrained Minimal Supersymmetric Standard Model, enlarged by three right handed neutrinos and their supersymmetric partners, and where the neutrino masses are generated via a seesaw mechanism. Two different scenarios with either universal or non-universal soft supersymmetry breaking Higgs masses at the gauge coupling unification scale are considered. In the first part we present a complete one-loop computation of the conversion rate for this process that includes the photon-, $Z$-boson, and Higgs-boson penguins, as well as box diagrams, and compare their size in the two considered scenarios. Then, in these two scenarios we analyse the relevance of the various parameters on the conversion rates, particularly emphasising the role played by the heavy neutrino masses, $\tan β$, and especially $θ_{13}$. In the case of hierachical heavy neutrinos, an extremely high sensitivity of the rates to $θ_{13}$ is indeed found. The last part of this work is devoted to the study of the interesting loss of correlation between the $μ-e$ conversion and $μ\to e γ$ rates that occurs in the non-universal scenario. In the case of large $\tan β$ and light $H^0$ Higgs boson an enhanced ratio of the $μ-e$ to $μ\to e γ$ rates, with respect to the universal case is found, and this could be tested with the future experimental sensitivities.

hep-ph↗
arXiv2007

Sensitivity to SUSY Seesaw Parameters and Lepton Flavour Violation

We address the constraints on the SUSY seesaw parameters arising from Lepton Flavour Violation observables. Working in the Constrained Minimal Supersymmetric Standard Model extended by three right-handed (s)neutrinos, we study the predictions for the branching ratios of $l_j \to l_i γ$ and $l_j \to 3 l_i$ channels. We impose compatibility with neutrino data, electric dipole moment bounds, and further require a successful baryon asymmetry of the Universe (via thermal leptogenesis). We emphasise the interesting interplay between $θ_{13}$ and the LFV muon decays, pointing out the hints on the SUSY seesaw parameters that can arise from measurements of $θ_{13}$ and LFV branching ratios. This is a brief summary of the work of Ref. \cite{Antusch:2006vw}.

hep-ph↗
arXiv2006

Impact of $θ_{13}$ on Lepton Flavour Violating processes within SUSY Seesaw

We study the impact of neutrino masses and mixings on LFV processes within the context of the supersymmetric seesaw scenario, where the CMSSM is extended by three right-handed (s)neutrinos. A hierarchical spectrum is considered for both heavy and light neutrinos. We systematically analyse the interesting relation between the leptonic mixing angle $θ_{13}$ and LFV muon and tau decays, namely $l_j \to l_i γ$ and $l_j \to 3 l_i$, and discuss the interplay with the other relevant parameters. We require compatibility with low energy neutrino data, bounds on both LFV decays and charged lepton electric dipole moments, and impose a successful baryogenesis via thermal leptogenesis. Particular emphasis is given to the implications that a future $θ_{13}$ measurement can have on our knowledge of the heavy neutrino sector.

hep-ph↗
arXiv2006

LFV in tau and muon decays within SUSY seesaw

In these proceedings we present the results for lepton flavour violating tau and muon decays within the SUSY seesaw scenario. Specifically, we consider the Constrained Minimal Supersymmetric Standard Model extended by three right handed neutrinos, $ν_{R_i}$ and their corresponding SUSY partners, ${\tilde ν}_{R_i}$, ($i=1,2,3$), and use the seesaw mechanism for neutrino mass generation. We include the predictions for the branching ratios of two types of lepton flavour violating channels, $l_j \to ł_i γ$ and $l_j \to 3 l_i$, and compare them with the present bounds and future experimental sensitivities. We first analyse the dependence of the branching ratios with the most relevant SUSY seesaw parameters, and we then focus on the particular sensitivity to $θ_{13}$, which we find specially interesting on the light of its potential future measurement. We further study the constraints from the requirement of successfully producing the baryon asymmetry of the Universe via thermal leptogenesis, which is another appealing feature of the SUSY seesaw scenario. We conclude with the impact that a potential measurement of $θ_{13}$ can have on lepton flavour violating physics. This is a very short summary of the works in Refs. \cite{Arganda:2005ji} and \cite{Antusch:2006vw} to which we refer the reader for more details.

hep-ph↗
arXiv2006

Lepton Flavor Violating tau and muon decays

In this work the following lepton flavor violating $τ$ and $μ$ decays are studied: $τ^- \to μ^- μ^- μ^+$, $τ^- \to e^- e^- e^+$, $μ^- \to e^- e^- e^+$, $τ^- \to μ^- γ$, $τ^- \to e^- γ$ and $μ^- \to e^- γ$. We work in a constrained supersymmetric scenario with universal soft breaking terms and where the MSSM particle content is extended by the addition of three heavy right handed Majorana neutrinos and their supersymmetric partners. The generation of neutrino masses is done via the seesaw mechanism. We analize all these lepton flavor violating decays in terms of the relevant input parameters, which are the usual mSUGRA parameters and the seesaw parameters. In the numerical analysis compatibility with the most recent experimental upper bounds on all these $τ$ and $μ$ decays, with the neutrino data, and with the present lower bounds on the supersymmetric particle masses are required. Two typical scenarios with degenerate and hierarchical heavy neutrinos are considered. We will show here that the minimal supergravity and seesaw parameters do get important restrictions from these $τ$ and $μ$ decays in the hierarchical neutrino case.

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arXiv2006

Testing Supersymmetry with Lepton Flavor Violating tau and mu decays

In this work the following lepton flavor violating $τ$ and $μ$ decays are studied: $τ^- \to μ^- μ^- μ^+$, $τ^- \to e^- e^- e^+$, $μ^- \to e^- e^- e^+$, $τ^- \to μ^- γ$, $τ^- \to e^- γ$ and $μ^- \to e^- γ$. We work in a supersymmetric scenario consisting of the minimal supersymmetric standard model particle content, extended by the addition of three heavy right handed Majorana neutrinos and their supersymmetric partners, and where the generation of neutrino masses is done via the seesaw mechanism. Within this context, a significant lepton flavor mixing is generated in the slepton sector due to the Yukawa neutrino couplings, which is transmited from the high to the low energies via the renormalization group equations. This slepton mixing then generates via loops of supersymmetric particles significant contributions to the rates of $l_j \to 3 l_i$ and the correlated $l_j \to l_i γ$ decays. We analize here in full detail these rates in terms of the relevant input parameters, which are the usual minimal supergravity parameters and the seesaw parameters. For the $l_j \to 3 l_i$ decays, a full one-loop analytical computation of all the contributing supersymmetric loops is presented. This completes and corrects previous computations in the literature. In the numerical analysis compatibility with the most recent experimental upper bounds on all these $τ$ and $μ$ decays, with the neutrino data, and with the present lower bounds on the supersymmetric particle masses are required. Two typical scenarios with degenerate and hierarchical heavy neutrinos are considered. We will show here that the minimal supergravity and seesaw parameters do get important restrictions from these $τ$ and $μ$ decays in the hierarchical neutrino case.

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arXiv2005

Lepton flavor changing Higgs boson decays in SUSY with $ν_R$

Lepton flavor violating Higgs boson decays (LFVHD) are studied in the context of the Minimal Supersymmetric Standard Model (MSSM) being embeded in a mSUGRA scenario that is enlarged with three right handed neutrinos and their supersymmetric partners, and with the neutrino masses being generated by the seesaw mechanism. We compute the partial widths for these decays to one-loop order and analyze numerically the corresponding branching ratios in terms of the mSUGRA and seesaw parameters. We analyze in parallel the lepton flavor changing $ł_j\to l_i γ$ decays and explore the maximum predicted rates for LFVHD, mainly for $H^0,A^0 \to τ{\bar μ}$ decays, by requiring compatibility with neutrino and $BR(ł_j\to l_i γ)$ data. We find LFVHD ratios of up to $10^{-5}$ in some regions of the MSSM-seesaw parameter space.

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