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Emmanuel-Costa, D., Simoes, C., & Tortola, M. (2013). The minimal adjoint-SU (5) x Z(4) GUT model. J. High Energy Phys., 10(10), 054–30pp.
Abstract: An extension of the adjoint SU (5) model with a flavour symmetry based on the Z(4) group is investigated. The Z(4) symmetry is introduced with the aim of leading the up-and down-quark mass matrices to the Nearest-Neighbour-Interaction form. As a consequence of the discrete symmetry embedded in the SU (5) gauge group, the charged lepton mass matrix also gets the same form. Within this model, light neutrinos get their masses through type-I, type-III and one-loop radiative seesaw mechanisms, implemented, respectively, via a singlet, a triplet and an octet from the adjoint fermionic 24 fields. It is demonstrated that the neutrino phenomenology forces the introduction of at least three 24 fermionic multiplets. The symmetry SU (5) x Z(4) allows only two viable zero textures for the effective neutrino mass matrix. It is showed that one texture is only compatible with normal hierarchy and the other with inverted hierarchy in the light neutrino mass spectrum. Finally, it is also demonstrated that Z(4) freezes out the possibility of proton decay through exchange of coloured Higgs triplets at tree-level.
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Hirsch, M., Lineros, R. A., Morisi, S., Palacio, J., Rojas, N., & Valle, J. W. F. (2013). WIMP dark matter as radiative neutrino mass messenger. J. High Energy Phys., 10(10), 149–18pp.
Abstract: The minimal seesaw extension of the Standard SU(3)(c)circle times SU(2)(L)circle times U(1)(Y) Model requires two electroweak singlet fermions in order to accommodate the neutrino oscillation parameters at tree level. Here we consider a next to minimal extension where light neutrino masses are generated radiatively by two electroweak fermions: one singlet and one triplet under SU(2)(L). These should be odd under a parity symmetry and their mixing gives rise to a stable weakly interactive massive particle (WIMP) dark matter candidate. For mass in the GeV-TeV range, it reproduces the correct relic density, and provides an observable signal in nuclear recoil direct detection experiments. The fermion triplet component of the dark matter has gauge interactions, making it also detectable at present and near future collider experiments.
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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). Differential branching fraction and angular analysis of the decay B-s(0) -> phi mu(+)mu(-). J. High Energy Phys., 07(7), 084–18pp.
Abstract: The determination of the differential branching fraction and the first angular analysis of the decay B-s(0) -> phi mu(+)mu(-) are presented using data, corresponding to an integrated luminosity of 1.0 fb(-1), collected by the LHCb experiment at root s = 7 TeV. The differential branching fraction is determined in bins of q(2), the invariant dimuon mass squared. Integration over the full q2 range yields a total branching fraction of B(B-s(0) -> phi mu(+)mu(-)) = (7.07(-0.59)(+0.64) +/- 0.17 +/- 0.71) x 10(-7), where the first uncertainty is statistical, the second systematic, and the third originates from the branching fraction of the normalisation channel. An angular analysis is performed to determine the angular observables F-L, S-3, A(6), and A(9). The observables are consistent with Standard Model expectations.
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Celis, A., Ilisie, V., & Pich, A. (2013). LHC constraints on two-Higgs doublet models. J. High Energy Phys., 07(7), 053–44pp.
Abstract: A new Higgs-like boson with mass around 126 GeV has recently been discovered at the LHC. The available data on this new particle is analyzed within the context of two-Higgs doublet models without tree-level flavour-changing neutral currents. Keeping the generic Yukawa structure of the Aligned Two-Higgs Doublet Model framework, we study the implications of the LHC data on the allowed scalar spectrum. We analyze both the CP-violating and CP-conserving cases, and a few particular limits with a reduced number of free parameters, such as the usual models based on discrete Z(2) symmetries.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fassi, F., Ferrer, A., et al. (2013). Search for new phenomena in final states with large jet multiplicities and missing transverse momentum at root s=8 TeV proton-proton collisions using the ATLAS experiment. J. High Energy Phys., 10(10), 130–50pp.
Abstract: A search is presented for new particles decaying to large numbers (7 or more) of jets, with missing transverse momentum and no isolated electrons or muons. This analysis uses 20.3 fb(-1) of p p collision data at root s = 8 TeV collected by the ATLAS experiment at the Large Hadron Collider. The sensitivity of the search is enhanced by considering the number of b-tagged jets and the scalar sum of masses of large-radius jets in an event. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of various simplified supersymmetry-inspired models where gluinos are pair produced, as well as an mSUGRA/CMSSM model.
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