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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Observations of Lambda(0)(b) -> Lambda K+pi(-) and Lambda(0)(b) -> Lambda K+K- decays and searches for other Lambda(0)(b) and Xi(0)(b) decays to Lambda h(+)h '(-) final states. J. High Energy Phys., 05(5), 081–22pp.
Abstract: A search is performed for the charmless three-body decays of the Lambda(0)(b) and Xi(0)(b) baryons to the final states Lambda h(+)h'(-), where h(') = pi or K. The analysis is based on a data sample, corresponding to an integrated luminosity of 3 fb-1 of pp collisions, collected by the LHCb experiment. The Lambda(0)(b) -> Lambda K+pi(-) and Lambda(0)(b) -> Lambda K+K- decays are observed for the first time and their branching fractions and CP asymmetry parameters are measured. Evidence is seen for the Lambda(0)(b) -> Lambda pi(+)pi(-) decay and limits are set on the branching fractions of Xi(0)(b) baryon decays to the Lambda h(+)h(-) final states.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurement of the properties of the Xi(b)(*0) baryon. J. High Energy Phys., 05(5), 161–19pp.
Abstract: We perform a search for near-threshold I (b) (0) resonances decaying to I (b) (-) pi (+) in a sample of proton-proton collision data corresponding to an integrated luminosity of 3 fb(-1) collected by the LHCb experiment. We observe one resonant state, with the following properties: m(Xi b*0) – m (Xi b-) – m (pi+) = 15.727 +/- 0.068 (stat) +/- 0.023 (syst) MeV/c2, Gamma(Xi b*0) = 0.90 +/- 0.16 (stat) +/- 0.08 (syst) MeV. This confirms the previous observation by the CMS collaboration. The state is consistent with the J (P) = 3/2(+)aEuro integral I (b) (au 0) resonance expected in the quark model. This is the most precise determination of the mass and the first measurement of the natural width of this state. We have also measured the ratio sigma(pp -> Xi b*0 X)B(Xi b*0 -> Xi b-pi+)/sigma(pp -> Xi b- X) = 0.28 +/- 0.03 (stat.) +/- 0.01 (syst).
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Observation of Lambda(0)(b) -> psi (2S)pK(-) and Lambda(0)(b) -> J/psi pi(+)pi(-)pK(-) decays and a measurement of the A(b)(0) baryon mass. J. High Energy Phys., 05(5), 132–22pp.
Abstract: The decays Lambda(0)(b) -> psi(2S)pK(-) and Lambda(0)(b) -> J/psi pi(+)pi(-)pK(-) are observed in a data sample corresponding to an integrated luminosity of 3 fb(-1), collected in proton-proton collisions at 7 and 8 TeV centre-of-mass energies by the LHCb detector. The psi(2S) mesons are reconstructed through the decay modes psi(2S) -> mu(+)mu(-) and psi(2S) -> J/psi pi(+)pi(-) The branching fractions relative to that of Lambda(0)(b) -> J/psi pk(-) are measured to be [GRAPHICS] where the first uncertainties are statistical, the second are systematic and the third is related to the knowledge of J/psi and psi(2S) branching fractions. The mass of the Ai baryon is measured to be M(Lambda(0)(b)) = 5619.65 +/- 0.17 0.17 MeV/c(2), where the uncertainties are statistical and systematic.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurement of forward W and Z boson production in association with jets in proton-proton collisions at root s=8 TeV. J. High Energy Phys., 05(5), 131–23pp.
Abstract: The production of W and Z bosons in association with jets is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 +/- 0.02 fb(-1). The W boson is identified using its decay to a muon and a neutrino, while the Z boson is identified through its decay to a muon pair. Total cross-sections are measured and combined into charge ratios, asymmetries, and ratios of W+jet and Z+jet production cross-sections. Differential measurements are also performed as a function of both boson and jet kinematic variables. All results are in agreement with Standard Model predictions.
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ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2016). Search for the Standard Model Higgs boson decaying into b(b)over-bar produced in association with top quarks decaying hadronically in pp collisions at root s=8 TeV with the ATLAS detector. J. High Energy Phys., 05(5), 160–51pp.
Abstract: A search for Higgs boson production in association with a pair of top quarks (t (t) over barH) is performed, where the Higgs boson decays to b (b) over bar, and both top quarks decay hadronically. The data used correspond to an integrated luminosity of 20.3 fb(-1) of pp collisions at root s = 8 TeV collected with the ATLAS detector at the Large Hadron Collider. The search selects events with at least six energetic jets and uses a boosted decision tree algorithm to discriminate between signal and Standard Model background. The dominant multijet background is estimated using a dedicated data-driven technique. For a Higgs boson mass of 125 GeV, an upper limit of 6.4 (5.4) times the Standard Model cross section is observed (expected) at 95% confidence level. The best-fit value for the signal strength is μ= 1.6 +/- 2.6 times the Standard Model expectation for m(H) = 125 GeV. Combining all t (t) over barH searches carried out by ATLAS at root s = 8 and 7 TeV, an observed (expected) upper limit of 3.1 (1.4) times the Standard Model expectation is obtained at 95% confidence level, with a signal strength μ= 1.7 +/- 0.8.
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NEXT Collaboration(Martin-Albo, J. et al), Muñoz Vidal, J., Ferrario, P., Nebot-Guinot, M., Gomez-Cadenas, J. J., Alvarez, V., et al. (2016). Sensitivity of NEXT-100 to neutrinoless double beta decay. J. High Energy Phys., 05(5), 159–30pp.
Abstract: NEXT-100 is an electroluminescent high-pressure xenon gas time projection chamber that will search for the neutrinoless double beta (0v beta beta) decay of Xe-136. The detector possesses two features of great value for 0v beta beta searches: energy resolution better than 1% FWHM at the Q value of Xe-136 and track reconstruction for the discrimination of signal and background events. This combination results in excellent sensitivity, as discussed in this paper. Material-screening measurements and a detailed Monte Carlo detector simulation predict a background rate for NEXT-100 of at most 4 x 10(-4) counts keV(-1) kg(-1) yr(-1). Accordingly, the detector will reach a sensitivity to the 0v beta beta-decay half-life of 2.8 x 10(25) years (90% CL) for an exposure of 100 kg.year, or 6.0 x 10(25) years after a run of 3 effective years.
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KM3NeT Collaboration(Adrian-Martinez, S. et al), Barrios-Marti, J., Calvo, D., Hernandez-Rey, J. J., Illuminati, G., Lotze, M., et al. (2017). Intrinsic limits on resolutions in muon- and electron-neutrino charged-current events in the KM3NeT/ORCA detector. J. High Energy Phys., 05(5), 008–39pp.
Abstract: Studying atmospheric neutrino oscillations in the few-GeV range with a multimegaton detector promises to determine the neutrino mass hierarchy. This is the main science goal pursued by the future KM3NeT/ORCA water Cherenkov detector in the Mediterranean Sea. In this paper, the processes that limit the obtainable resolution in both energy and direction in charged-current neutrino events in the ORCA detector are investigated. These processes include the composition of the hadronic fragmentation products, the subsequent particle propagation and the photon-sampling fraction of the detector. GEANT simulations of neutrino interactions in seawater produced by GENIE are used to study the effects in the 1-20 GeV range. It is found that fluctuations in the hadronic cascade in conjunction with the variation of the inelasticity y are most detrimental to the resolutions. The effect of limited photon sampling in the detector is of significantly less importance. These results will therefore also be applicable to similar detectors/media, such as those in ice.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Study of the D(0)p amplitude in Lambda(0)(b) -> D(0)p pi(-) decays. J. High Energy Phys., 05(5), 030–43pp.
Abstract: An amplitude analysis of the decay Lambda(0)(b) -> D(0)p pi(-) is performed in the part of the phase space containing resonances in the D(0)p channel. The study is based on a data sample corresponding to an integrated luminosity of 3.0 fb(-1) of pp collisions recorded by the LHCb experiment. The spectrum of excited Lambda(+)(c) states that decay into D(0)p is studied. The masses, widths and quantum numbers of the Lambda(c)(2880)(+) and Lambda(c) (2940)(+) resonances are measured. The constraints on the spin and parity for the Lambda(c)(2940)(+) state are obtained for the first time. A near-threshold enhancement in the D(0)p amplitude is investigated and found to be consistent with a new resonance, denoted the Lambda(c) (2860)(+), of spin 3/2 and positive parity.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Search for the B-s(0) -> eta'phi decay. J. High Energy Phys., 05(5), 158–18pp.
Abstract: A search for the charmless B-s(0) -> eta'phi decay is performed using pp collision data collected by the LHCb experiment at centre-of-mass energies of 7 and 8TeV, corresponding to an integrated luminosity of 3 fb(-1). No signal is observed and upper limits on the B-s(0) -> eta'phi branching fraction are set to 0.82 x 10(-6) at 90% and 1.01 x 10(-6) at 95% confidence level.
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Reig, M., Valle, J. W. F., & Vaquera-Araujo, C. A. (2017). Three-family left-right symmetry with low-scale seesaw mechanism. J. High Energy Phys., 05(5), 100–10pp.
Abstract: We suggest a new left-right symmetric model implementing a low-scale see-saw mechanism in which quantum consistency requires three families of fermions. The symmetry breaking route to the Standard Model determines the profile of the “next” expected new physics, characterized either by the simplest left-right gauge symmetry or by the 3-3-1 scenario. The resulting Z' gauge bosons can be probed at the LHC and provide a production portal for the right-handed neutrinos. On the other hand, its flavor changing interactions would affect the K, D and B neutral meson systems.
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