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 fraction
s $R$ = BR($H to b bar b$)/BR($H to tau^+ tau^-$) 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 $tanbeta$, 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.
We calculate the predictions for lepton flavour violating (LFV) tau and muon decays, $l_j to l_i gamma$, $l_j to 3 l_i$, $mu-e$ conversion in nuclei and LFV semileptonic tau decays $tau to mu PP$ with $PP= pi^+pi^-, pi^0pi^0, K^+K^-, K^0 {bar K}^0$ $
tau to mu P$ with $P=pi^0, eta, eta$ and $tau to mu V$ with $V = rho^0, phi$, 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.
In this work we study the Lepton Flavour Violating semileptonic $tau$ decays: 1) $tau to mu PP$ with $PP= pi^+pi^-, pi^0pi^0, K^+K^-, K^0 {bar K}^0$; 2) $tau to mu P$ with $P=pi^0, eta, eta$ and 3) $tau to mu V$ with $V = rho^0, phi$. 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 $gamma$-, $Z$-, 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($tau to mu eta$), BR($tau to mu eta$) and BR($tau to mu K^+K^-$) 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.
Here we update the predictions for lepton flavour violating tau and muon decays, $l_j to l_i gamma$, $l_j to 3 l_i$, and $mu-e$ conversion in nuclei. We work within a SUSY-seesaw context where the particle content of the Minimal Supersymmetric Standa
rd 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.
In this paper we study $mu-e$ 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 vi
a 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, $tan beta$, and especially $theta_{13}$. In the case of hierachical heavy neutrinos, an extremely high sensitivity of the rates to $theta_{13}$ is indeed found. The last part of this work is devoted to the study of the interesting loss of correlation between the $mu-e$ conversion and $mu to e gamma$ rates that occurs in the non-universal scenario. In the case of large $tan beta$ and light $H^0$ Higgs boson an enhanced ratio of the $mu-e$ to $mu to e gamma$ rates, with respect to the universal case is found, and this could be tested with the future experimental sensitivities.
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 $l_j to l_i gamma$ 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 $theta_{13}$ and the LFV muon decays, pointing out the hints on the SUSY seesaw parameters that can arise from measurements of $theta_{13}$ and LFV branching ratios. This is a brief summary of the work of Ref. cite{Antusch:2006vw}.
