[en] Adetailed study of top-quark polarizations and tt^- charge asymmetries, induced by top-squark-pair production at the LHC and the subsequent decays t → tχ₁⁰, 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 MadGraph in order to investigate the possibilities of the charge asymmetry A_C, measured at the LHC and consistent with SM expectations, to discriminate between different SUSY scenarios and analyze the implications of these scenarios in the top polarizations and related observables. (orig.)

[en] 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_Ri and their corresponding SUSY partners, ν-tilde _Ri,(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→l_iγ and l_j→3l_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 θ₁₃, 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 θ₁₃ can have on lepton flavour violating physics. This is a very short summary of the works in Refs. [E. Arganda and M.J. Herrero, Phys. Rev. D 73 (2006) 055003, (hep-ph/0510405)] and [S. Antusch, E. Arganda, M.J. Herrero and A. Teixeira, (hep-ph/0607263), to appear in JHEP] to which we refer the reader for more details

[en] 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 belongs to models of new physics with an extended Higgs sector, as the MSSM or 2HDM. The ratio of branching fractions R = BR(H → b anti b)/BR(H → τ"+τ"-) of Higgs-boson decays is a powerful tool in distinguishing 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 tan β, 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. (orig.)

[en] Here we review the main results of LFV in the semileptonic tau decays τ→μPP(PP = π⁺π^-, π⁰π⁰, K⁺K^-, K⁰K-bar⁰), τ→μP(P = π,η,η'), and τ→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.

No abstract available

[en] 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 τ and μ leptons, searching for their maximum rates that are allowed by present constraints from τ→μγ data and beyond Standard Model Higgs boson searches at the LHC, are also included.

[en] The search for heavy Higgs bosons at the LHC represents an intense experimental program, carried out by the ATLAS and CMS collaborations, which includes the hunt for invisible Higgs decays and dark matter candidates. No significant deviations from the SM backgrounds have been observed in any of these searches, imposing significant constraints on the parameter space of different new physics models with an extended Higgs sector. Here we discuss an alternative search strategy for heavy Higgs bosons decaying invisibly at the LHC, focusing on the pair production of a heavy scalar H together with a pseudoscalar A, through the production mode $q\overline{q}\to Z^{⁎}\to HA$. We identify as the most promising signal the final state made up of $4b+{E_T}^{\text{miss}}$, coming from the heavy scalar decay mode $H\to hh\to b\overline{b}b\overline{b}$, with h being the discovered SM-like Higgs boson with $m_h=125\text{GeV}$, together with the invisible channel of the pseudoscalar. We work within the context of simplified MSSM scenarios that contain quite heavy sfermions of most types with $\mathcal{O}(10)\text{TeV}$ masses, while the stops are heavy enough to reproduce the 125 GeV mass for the lightest SM-like Higgs boson. By contrast, the gauginos/higgsinos and the heavy MSSM Higgs bosons have masses near the EW scale. Our search strategies, for a LHC center-of-mass energy of $\sqrt{s}=14\text{TeV}$, allow us to obtain statistical significances of the signal over the SM backgrounds with values up to $\sim 1.6\sigma$ and $\sim 3\sigma$, for total integrated luminosities of $300{\text{fb}}^{-1}$ and $1000{\text{fb}}^{-1}$, respectively.

[en] 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, ν_Ri and their corresponding SUSY partners, ν-tilde_Ri, (i=1,2,3). 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 tanβ, 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. [E. Arganda, M. J. Herrero and J. Portoles, JHEP 0806 (2008) 079 [(arXiv:0803.2039 [hep-ph])]] and [E. Arganda, M. J. Herrero and A. M. Teixeira, JHEP 0710 (2007) 104 [(arXiv:0707.2955 [hep-ph])]] to which we refer the reader for more details.

[en] A thorough search of the sky exposed at the Pierre Auger Cosmic Ray Observatory reveals no statistically significant excess of events in any small solid angle that would be indicative of a flux of neutral particles from a discrete source. The search covers from –90° to +15° in declination using four different energy ranges above 1 EeV (10¹⁸ eV). The method used in this search is more sensitive to neutrons than to photons. The upper limit on a neutron flux is derived for a dense grid of directions for each of the four energy ranges. These results constrain scenarios for the production of ultrahigh energy cosmic rays in the Galaxy.

[en] A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 10¹⁸ eV at the Pierre Auger Observatory is reported. For the first time, these large-scale anisotropy searches are performed as a function of both the right ascension and the declination and expressed in terms of dipole and quadrupole moments. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Upper limits on dipole and quadrupole amplitudes are derived under the hypothesis that any cosmic ray anisotropy is dominated by such moments in this energy range. These upper limits provide constraints on the production of cosmic rays above 10¹⁸ eV, since they allow us to challenge an origin from stationary galactic sources densely distributed in the galactic disk and emitting predominantly light particles in all directions.