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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., & Ruiz Valls, P. (2014). Precision measurement of the ratio of the Lambda(0)(b) to (B)over-bar(0) lifetimes. Phys. Lett. B, 734, 122–130.
Abstract: The LHCb measurement of the lifetime ratio of the Lambda(0)(b) baryon to the (B) over bar (0) meson is updated using data corresponding to an integrated luminosity of 3.0 fb(-1) collected using 7 and 8 TeV centre-of-mass energy pp collisions at the LHC. The decay modes used are Lambda(0)(b) -> J/psi pK(-) and (B) over bar (0) -> J/psi pi K-+(-), where the pi K-+(-) mass is consistent with that of the (K) over bar*(0)(892) meson. The lifetime ratio is determined with unprecedented precision to be 0.974 +/- 0.006 +/- 0.004, where the first uncertainty is statistical and the second systematic. This result is in agreement with original theoretical predictions based on the heavy quark expansion. Using the current world average of the (B) over bar (0) lifetime, the Lambda(0)(b) lifetime is found to be 1.479 +/- 0.009 +/- 0.010 ps.
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Chachamis, G., Hentschinski, M., Madrigal Martinez, J. D., & Sabio Vera, A. (2014). Forward jet production and quantum corrections to the gluon Regge trajectory from Lipatov's high energy effective action. Phys. Part. Nuclei, 45(4), 788–799.
Abstract: We review Lipatov's high energy effective action and show that it is a useful computational tool to calculate scattering amplitudes in (quasi)-multi-Regge kinematics. We explain in some detail our recent work where a novel regularization and subtraction procedure has been proposed that allows to extend the use of this effective action beyond tree level. Two examples are calculated at next-to-leading order: forward jet vertices and the gluon Regge trajectory.
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Boucenna, M. S., Morisi, S., & Valle, J. W. F. (2014). The Low-Scale Approach to Neutrino Masses. Adv. High. Energy Phys., 2014, 831598–15pp.
Abstract: In this short review we revisit the broad landscape of low-scale SU(3)(C) circle times SU(2)(L) circle times U(1)(Y) models of neutrino mass generation, with view on their phenomenological potential. This includes signatures associated to direct neutrino mass messenger production at the LHC, as well as messenger-induced lepton flavor violation processes. We also briefly comment on the presence of WIMP cold dark matter candidates.
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Gonzalez Felipe, R., & Serodio, H. (2014). Abelian realization of phenomenological two-zero neutrino textures. Nucl. Phys. B, 886, 75–92.
Abstract: In an attempt at explaining the observed neutrino mass-squared differences and leptonic mixing, lepton mass matrices with zero textures have been widely studied. In the weak basis where the charged lepton mass matrix is diagonal, various neutrino mass matrices with two zeros have been shown to be consistent with the current experimental data. Using the canonical and Smith normal form methods, we construct the minimal Abelian symmetry realizations of these phenomenological two-zero neutrino textures. The implementation of these symmetries in the context of the seesaw mechanism for Majorana neutrino masses is also discussed.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Evidence for the decay X(3872) -> psi(2S)gamma. Nucl. Phys. B, 886, 665–680.
Abstract: Evidence for the decay mode X(3872) -> psi(2S)gamma in B+ -> X(3872)K+ decays is found with a significance of 4.4 standard deviations. The analysis is based on a data sample of proton proton collisions, corresponding to an integrated luminosity of 3 fb(-1), collected with the LHCb detector, at centre-of-mass energies of 7 and 8 TeV. The ratio of the branching fraction of the X(3872) -> psi(2S)gamma decay to that of the X(3872) -> J/psi gamma decay is measured to be B(X(3872) -> psi(2S)gamma)/B(X(3872) -> J/psi gamma) = 2.46 +/- 0.64 +/- 0.29, where the first uncertainty is statistical and the second is systematic. The measured value does not support a pure D (D) over bar* molecular interpretation of the X(3872) state.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Measurement of the Xi(-)(b) and Omega(-)(b) baryon lifetimes. Phys. Lett. B, 736, 154–162.
Abstract: Using a data sample of pp collisions corresponding to an integrated luminosity of 3 fb(-1), the Xi(-)(b) and Omega(-)(b) baryons are reconstructed in the Xi(-)(b) -> J/psi Xi(-) and Omega(-)(b) -> J/psi Omega(-) decay modes and their lifetimes measured to be tau(Xi(-)(b)) = 1.55(-0.09)(+0.10) (stat) +/- 0.03 (syst) ps, tau(Omega(-)(b)) = 1.54(-0.21)(+0.26) (stat) +/- 0.05 (syst) ps. These are the most precise determinations to date. Both measurements are in good agreement with previous experimental results and with theoretical predictions.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Measurement of the CP-violating phase phi(s) in (B)over-bar(s)(0) -> J / psi pi(+)pi(-) decays. Phys. Lett. B, 736, 186–195.
Abstract: The mixing-induced CP-violating phase phi(s) in B-s(0) and (B) over bar (0)(s) decays is measured using the J / psi pi(+)pi(-) final state in data, taken from 3 fb(-1) of integrated luminosity, collected with the LHCb detector in 7 and 8 TeV centre-of-mass pp collisions at the LHC. A time-dependent flavour-tagged amplitude analysis, allowing for direct CP violation, yields a value for the phase phi(s) = 70 +/- 68 +/- 8 mrad. This result is consistent with the Standard Model expectation and previous measurements.
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Pallis, C., & Shafi, Q. (2014). From hybrid to quadratic inflation with high-scale supersymmetry breaking. Phys. Lett. B, 736, 261–266.
Abstract: Motivated by the reported discovery of inflationary gravity waves by the BICEP2 experiment, we propose an inflationary scenario in supergravity, based on the standard superpotential used in hybrid inflation. The new model yields a tensor-to-scalar ratio r similar or equal to 0.14 and scalar spectral index n(s) similar or equal to 0.964, corresponding to quadratic (chaotic) inflation. The important new ingredients are the high-scale, (1.6-10) . 10(13) GeV, soft supersymmetry breaking mass for the gauge singlet inflaton field and a shift symmetry imposed on the Kahler potential. The end of inflation is accompanied, as in the earlier hybrid inflation models, by the breaking of a gauge symmetry at (1.2-7.1) . 10(16) GeV, comparable to the grand-unification scale.
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Vijande, J., & Valcarce, A. (2014). Unraveling the pattern of the XYZ mesons. Phys. Lett. B, 736, 325–328.
Abstract: We present a plausible mechanism for the origin of the XYZ mesons in the heavy meson spectra within a standard quark-model picture. We discuss the conditions required for the existence of four-quark bound states or resonances contributing to the heavy meson spectra, being either compact or molecular. We concentrate on charmonium and bottomonium spectra, where several new states, difficult to understand as simple quark-antiquark pairs, have been reported by different experimental collaborations. The pivotal role played by entangled meson-meson thresholds is emphasized.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Effective lifetime measurements in the B-s(0) -> K+K-, B-0 -> K+pi(-) and B-s(0) -> pi K-+(-) decays. Phys. Lett. B, 736, 446–454.
Abstract: Measurements of the effective lifetimes in the B-s(0) -> K+K-, B-0 -> K+pi(-) and B-s(0) -> pi K-+(-) decays are presented using 1.0 fb(-1)of pp collision data collected at a centre-of-mass energy of 7 TeV by the LHCb experiment. The analysis uses a data-driven approach to correct for the decay time acceptance. The measured effective lifetimes are tau(Bs0 -> K+K-) = 1.407 +/- 0.016 (stat) +/- 0.007 (syst) ps, tau(Bs0 -> K+pi-) = 1.524 +/- 0.011 (stat) +/- 0.004 (syst) ps, tau(Bs0 ->pi+K-) = 1.60 +/- 0.06 (stat) +/- 0.01 (syst) ps. This is the most precise determination to date of the effective lifetime in the B-s(0) -> K+K- decay and provides constraints on contributions from physics beyond the Standard Model to the B-s(0) mixing phase and the width difference Delta Gamma(s).
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