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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). Limits on neutral Higgs boson production in the forward region in pp collisions at root s=7 TeV. J. High Energy Phys., 05(5), 132–13pp.
Abstract: Limits on the cross-section times branching fraction for neutral Higgs bosons, produced in p p collisions at root s = 7 TeV, and decaying to two tau leptons with pseudorapidities between 2.0 and 4.5, are presented. The result is based on a dataset, corresponding to an integrated luminosity of 1.0 fb(-1), collected with the LHCb detector. Candidates are identified by reconstructing final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. A model independent upper limit at the 95% confidence level is set on a neutral Higgs boson cross-section times branching fraction. It varies from 8.6 pb for a Higgs boson mass of 90 GeV to 0.7 pb for a Higgs boson mass of 250 GeV, and is compared to the Standard Model expectation. An upper limit on tan beta in the Minimal Supersymmetric Model is set in the m(h0)(max) scenario. It ranges from 34 for a CP-odd Higgs boson mass of 90 GeV to 70 for a pseudo-scalar Higgs boson mass of 140 GeV.
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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). Measurement of the B-0 -> K*(0) e(+) e(-) branching fraction at low dilepton mass. J. High Energy Phys., 05(5), 159–18pp.
Abstract: The branching fraction of the rare decay B-0 -> K*(0) e(+) e(-) in the dilepton mass region from 30 to 1000 MeV/c(2) has been measured by the LHCb experiment, using pp collision data, corresponding to an integrated luminosity of 1.0 fb(-1), at a centre-of-mass energy of 7 TeV. The decay mode B-0 -> J/psi (e(+) e(-)) K*(0) is utilized as a normalization channel. The branching fraction B(B-0 -> K*(0) e(+) e(-)) is measured to be B(B-0 -> K*(0) e(+) e(-))(30-1000 MeV/c2) = (3.1(-0.8)(-0.3)(+0.9)(+0.2) +/- 0.2) x 10(-7) where the fi rst error is statistical, the second is systematic, and the third comes from the uncertainties on the B-0 -> J/K*(0) and J/psi -> e(+) e(-) branching fractions.
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Galli, P., Meessen, P., & Ortin, T. (2013). The Freudenthal gauge symmetry of the black holes of N=2, d=4 supergravity. J. High Energy Phys., 05(5), 011–15pp.
Abstract: We show that the representation of black-hole solutions in terms of the variables H-M which are harmonic functions in the supersymmetric case is non-unique due to the existence of a local symmetry in the effective action. This symmetry is a continuous (and local) generalization of the discrete Freudenthal transformations initially introduced for the black-hole charges and can be used to rewrite the physical fields of a solution in terms of entirely different-looking functions.
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Marzocca, D., Petcov, S. T., Romanino, A., & Sevilla, M. C. (2013). Nonzero |U_e3| from charged lepton corrections and the atmospheric neutrino mixing angle. J. High Energy Phys., 05(5), 073–27pp.
Abstract: After the successful determination of the reactor neutrino mixing angle theta(13) not equal 0.16 not equal 0, a new feature suggested by the current neutrino oscillation data is a sizeable deviation of the atmospheric neutrino mixing angle theta(23) from pi/4. Using the fact that the neutrino mixing matrix U = (UeU nu)-U-dagger, where U-e and U-nu result from the diagonalisation of the charged lepton and neutrino mass matrices, and assuming that U-nu has a i) bimaximal (BM), H) tri-bimaximal (TBM) form, or else Hi) corresponds to the conservation of the lepton charge L' = L-e – L μ- L-tau (LC), we investigate quantitatively what are the minimal forms of U-e, in terms of angles and phases it contains, that can provide the requisite corrections to U-nu so that theta(13), theta(23) and the solar neutrino mixing angle theta(12) have values compatible with the current data. Two possible orderings of the 12 and the 23 rotations in U-e, “standard” and “inverse”, are considered. The results we obtain depend strongly on the type of ordering. In the case of “standard” ordering, in particular, the Dirac CP violation phase delta, present in U, is predicted to have a value in a narrow interval around i) delta similar or equal to pi in the BM (or LC) case, H) delta congruent to 3 pi/2 or pi/2 in the TBM case, the CP conserving values delta = 0, pi, 2 pi being excluded in the TBM case at more than 4 sigma.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Measurement of polarization amplitudes and CP asymmetries in B-0 -> phi K*(892)(0). J. High Energy Phys., 05(5), 069–24pp.
Abstract: An angular analysis of the decay B (0) -> phi K (*)(892)(0) is reported based on a pp collision data sample, corresponding to an integrated luminosity of 1.0 fb(-1), collected at a centre-of-mass energy of root S = 7 TeV with the LHCb detector. The P-wave amplitudes and phases are measured with a greater precision than by previous experiments, and confirm about equal amounts of longitudinal and transverse polarization. The S-wave K+ pi(-) and K+ K- contributions are taken into account and found to be significant. A comparison of the B (0) -> phi K (*)(892)(0) and results shows no evidence for direct CP violation in the rate asymmetry, in the triple-product asymmetries or in the polarization amplitudes and phases.
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Della Morte, M., Dooling, S., Heitger, J., Hesse, D., & Simma, H. (2014). Matching of heavy-light flavour currents between HQET at order 1/m and QCD: I. Strategy and tree-level study. J. High Energy Phys., 05(5), 060–31pp.
Abstract: We present a strategy how to match the full set of components of the heavy-light axial and vector currents in Heavy Quark Effective Theory (HQET), up to and including 1/m (h) -corrections, to QCD. While the ultimate goal is to apply these matching conditions non-perturbatively, in this study we first have implemented them at tree-level, in order to find good choices of the matching observables with small contributions. They can later be employed in the non-perturbative matching procedure which is a crucial part of precision HQET computations of semileptonic decay form factors in lattice QCD.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Angular analysis of charged and neutral B -> K mu(+) mu(-) decays. J. High Energy Phys., 05(5), 082–25pp.
Abstract: The angular distributions of the rare decays B+ -> K+mu(+)mu(-) and B-0 -> K-S(0)mu(+)mu(-) are studied with data corresponding to 3 fb(-1) of integrated luminosity, collected in proton-proton collisions at 7 and 8 TeV centre-of-mass energies with the LHCb detector. The angular distribution is described by two parameters, F-H and the forward-backward asymmetry of the dimuon system A(FB), which are determined in bins of the dimuon mass squared. The parameter F-H is a measure of the contribution from (pseudo)scalar and tensor amplitudes to the decay width. The measurements of A(FB) and F-H reported here are the most precise to date and are compatible with predictions from the Standard Model.
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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. (2014). Search for direct production of charginos, neutralinos and sleptons in final states with two leptons and missing transverse momentum in pp collisions at root s=8 TeV with the ATLAS detector. J. High Energy Phys., 05(5), 071–52pp.
Abstract: Searches for the electroweak production of charginos, neutralinos and sleptons in final states characterized by the presence of two leptons (electrons and muons) and missing transverse momentum are performed using 20.3 fb(-1) of proton-proton collision data at root s = 8 TeV recorded with the ATLAS experiment at the Large Hadron Collider. No significant excess beyond Standard Model expectations is observed. Limits are set on the masses of the lightest chargino, next-to-lightest neutralino and sleptons for different lightest-neutralino mass hypotheses in simplified models. Results are also interpreted in various scenarios of the phenomenological Minimal Supersymmetric Standard Model.
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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. (2014). Measurement of the production of a W boson in association with a charm quark in pp collisions at root s=7 TeV with the ATLAS detector. J. High Energy Phys., 05(5), 068–67pp.
Abstract: The production of a W boson in association with a single charm quark is studied using 4.6 fb(-1) of pp collision data at root s = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96(-0.30)(+0.26) at Q (2) = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio sigma(W (+) +)/sigma(W (-) + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s-(s) over bar quark asymmetry.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., & Ruiz Valls, P. (2014). Evidence for the decay B-c(+) -> J/psi 3 pi(+)2 pi(-). J. High Energy Phys., 05(5), 148–17pp.
Abstract: Evidence is presented for the decay B-c(+) -> J/psi 3 pi(+)2 pi(-) using proton-proton collision data, corresponding to an integrated luminosity of 3 fb(-1), collected with the LHCb detector. A signal yield of 32 +/- 8 decays is found with a significance of 4.5 standard deviations. The ratio of the branching fraction of the B-c(+) -> J/psi 3 pi(+)2 pi(-) decay to that of the B-c(+) -> J/psi pi(+) decay is measured to be B(B-c(+) -> J/psi 3 pi(+)2 pi(-))/B(B-c(+) -> J/psi pi(+)) = 1.74 +/- 0.44 +/- 0.24, where the first uncertainty is statistical and the second is systematic.
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