377 research outputs found
Lepton Flavour Violation in charged leptons within SUSY-seesaw
In this paper we review our main results for Lepton Flavour Violating (LFV)
semileptonic tau decays and muon-electron conversion in nuclei within the
context of two Constrained SUSY-Seesaw Models, the CMSSM and the NUHM. The
relevant spectrum is that of the Minimal Supersymmetric Standard Model extended
by three right handed neutrinos, and their corresponding SUSY
partners, , (). We use the seesaw mechanism for
neutrino mass generation and choose a parameterisation of this mechanism that
allows us to incorporate the neutrino data in our analysis of LFV processes. In
addition to the full one-loop results for the rates of these processes, we will
also review the set of simple formulas, valid at large , which are
very useful to compare with present experimental bounds. The sensitivity to
SUSY and Higgs sectors in these processes will also be discussed. This is a
very short summary of the works in Refs. \cite{Arganda:2008jj} and
\cite{Arganda:2007jw} to which we refer the reader for more details.Comment: 6 pages, 6 figures. To be published in the proceedings of the Tau08
Conference, Novosibirsk, Russia, 22-25 September 200
Top-quark Polarization and Asymmetries at the LHC in the Effective Description of Squark Interactions
A detailed study of top-quark polarizations and charge
asymmetries, induced by top-squark-pair production at the LHC and the
subsequent decays , 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 ,
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.Comment: LaTeX file. 27 pages, 6 figures, 10 tables: v3 matches published
manuscript Eur.Phys.J. C75 (2015) 1, 3
Discriminating between SUSY and Non-SUSY Higgs Sectors through the Ratio 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 = BR()/BR() 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 , 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 which improves previous analyses and sets the level of accuracy
needed to discriminate between models.Comment: 11 pages, 3 figures, 1 tabl
Imprints of massive inverse seesaw model neutrinos in lepton flavor violating Higgs boson decays
In this paper we consider a Higgs boson with mass and other properties
compatible with those of the recently discovered Higgs particle at the LHC, and
explore the possibility of new Higgs leptonic decays, beyond the standard
model, with the singular feature of being lepton flavor violating (LFV). We
study these LFV Higgs decays, , within the context of the
inverse seesaw model (ISS) and consider the most generic case where three
additional pairs of massive right-handed singlet neutrinos are added to the
standard model particle content. We require in addition that the input
parameters of this ISS model are compatible with the present neutrino data and
other constraints, like perturbativity of the neutrino Yukawa couplings. We
present a full one-loop computation of the BR() rates for
the three possible channels, , and analyze in full detail the predictions as functions of the
various relevant ISS parameters. We study in parallel the correlated one-loop
predictions for the radiative decays, , within this same
ISS context, and require full compatibility of our predictions with the present
experimental bounds for the three radiative decays, , , and . After exploring the ISS parameter
space we conclude on the maximum allowed LFV Higgs decay rates within the ISS.Comment: 29 pages, 13 figures, 1 table, 1 appendix: v4 matches the manuscript
published in PR
Exotic events from heavy ISS neutrinos at the LHC
In this letter we study new relevant phenomenological consequences of the
right-handed heavy neutrinos with masses at the TeV energy scale,
working within the context of the Inverse Seesaw Model that includes three
pairs of quasi-degenerate pseudo-Dirac heavy neutrinos. We propose a new exotic
signal of these heavy neutrinos at the CERN Large Hadron Collider containing a
muon, a tau lepton, and two jets in the final state, which is based on the
interesting fact that this model can incorporate large Lepton Flavor Violation
for specific choices of the relevant parameters, particularly, the neutrino
Yukawa couplings. We will show here that an observable number of
exotic events, without missing energy, can be produced at this ongoing run of
the LHC.Comment: 7 pages, 4 figures. This version v3 matches the manuscript published
in Physics Letters
Analysis of the decays induced from SUSY loops within the Mass Insertion Approximation
In this paper we study the lepton favor violating decay channels of the
neutral Higgs bosons of the Minimal Supersymmetric Standard Model into a lepton
and an anti-lepton of different flavor. We work in the context of the most
general flavor mixing scenario in the slepton sector, in contrast to the
minimal flavor violation assumption more frequently used. Our analytic
computation is a one-loop diagrammatic one, but in contrast to the full
one-loop computation which is usually referred to the physical slepton mass
basis, we use here instead the Mass Insertion Approximation (MIA) which uses
the electroweak interaction slepton basis and treats perturbatively the mass
insertions changing slepton flavor. By performing an expansion in powers of the
external momenta in the relevant form factors, we will be able to separate
explicitly in the analytic results the leading non-decoupling (constant at
asymptotically large sparticle masses) and the next to leading decoupling
contributions (decreasing with the sparticle masses). Our final aim is to
provide a set of simple analytic formulas for the form factors and the
associated effective vertices, that we think may be very useful for future
phenomenological studies of the lepton flavor violating Higgs boson decays, and
for their comparison with data. The accuracy of the numerical results obtained
with the MIA are also analyzed and discussed here in comparison with the full
one-loop results. Our most optimistic numerical estimates for the three neutral
Higgs boson decays channels into and leptons, searching for their
maximum rates that are allowed by present constraints from data and beyond Standard Model Higgs boson searches at the LHC, are
also included.Comment: 37 pages, 16 figures, 3 appendices. This version v3 matches the
manuscript published in JHE
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