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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). Observation of the suppressed ADS modes B-+/- -> [pi K-+/-(-/+)pi(+)pi(-)](D)K-+/- and B-+/- -> [pi K-+/-(-/+)pi(+)pi(-)](D)pi(+/-). Phys. Lett. B, 723(1-3), 44–53.
Abstract: An analysis of and B-+/- -> DK +/- and B-+/- -> D pi(+/-) decays is presented where the D meson is reconstructed in the four-body final state K-+/-pi(-/+)pi(+)pi(-). Using LHCb data corresponding to an integrated luminosity of 1.0 fb(-1), first observations are made of the suppressed ADS modes B-+/- ->[pi K-+/-(-/+)pi(+)pi(-)](D)K-+/- and B +/- -> [pi K-+/-(-/+)pi(+)pi(-)](D)pi(+/-) with a significance of 5.1 sigma and greater than 10 sigma, respectively. Measurements of CP asymmetries and CP-conserving ratios of partial widths from this family of decays are also performed. The magnitude of the ratio between the suppressed and favoured B-+/- -> DK +/- amplitudes is determined to be r(B)(K) = 0.097 +/- 0.011.
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Bernal, N., Boehm, C., Palomares-Ruiz, S., Silk, J., & Toma, T. (2013). Observing Higgs boson production through its decay into gamma-rays: A messenger for dark matter candidates. Phys. Lett. B, 723(1-3), 100–106.
Abstract: In this Letter, we study the gamma-ray signatures subsequent to the production of a Higgs boson in space by dark matter annihilations. We investigate the cases where the Higgs boson is produced at rest or slightly boosted and show that such configurations can produce characteristic bumps in the gamma-ray data. These results are relevant in the case of the Standard Model-like Higgs boson provided that the dark matter mass is about 63 GeV, 109 GeV or 126 GeV, but can be generalized to any other Higgs boson masses. Here, we point out that it may be worth looking for a 63 GeV line since it could be the signature of the decay of a Standard Model-like Higgs boson produced in space, as in the case of a di-Higgs final state if m chi similar or equal to 126 GeV. We show that one can set generic constraints on the Higgs boson production rates using its decay properties. In particular, using the Fermi-LAT data from the galactic center, we find that the dark matter annihilation cross section into gamma+ a Standard Model-like Higgs boson produced at rest or near rest cannot exceed (sigma nu) similar to a few 10(-25) cm(3)/s or (sigma-nu) similar to a few 10(-27) cm(3)/s respectively, providing us with information on the Higgs coupling to the dark matter particle. We conclude that Higgs bosons can indeed be used as messengers to explore the dark matter mass range.
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Denis Bacelar, A. M. et al, Algora, A., Molina, F., & Rubio, B. (2013). The population of metastable states as a probe of relativistic-energy fragmentation reactions. Phys. Lett. B, 723(4-5), 302–306.
Abstract: Isomeric ratios have been measured for high-spin states in Po-198,200,206,208(84), At-208,209,210,211(85), Rn-210,211,212,213,214(86), Fr-208,211,212,213,214(87), Ra-210,211,212,214,215(88), and Ac-215(89) following the projectile fragmentation of a 1 AGeV U-238 beam by a Be-9 target at GSI Helmholtzzentrum fur Schwerionenforschung. The fragments were separated in the fragment separator (FRS) and identified by means of energy loss and time-of-flight techniques. They were brought to rest at the centre of the RISING gamma-ray detector array and intensities of gamma rays emitted in the decay of isomeric states with half-lives between 100 ns and 40 μs and spin values up to 55/2 (h) over bar were used to obtain the corresponding isomeric ratios. The data are compared to theoretical isomeric ratios calculated in the framework of the abrasion-ablation model. Large experimental enhancements are obtained for high-spin isomers in comparison to expected values.
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Botella, F. J., Branco, G. C., & Rebelo, M. N. (2013). Invariants and flavour in the general Two Higgs Doublet Model. Phys. Lett. B, 722(1-3), 76–82.
Abstract: The flavour structure of the general Two Higgs Doublet Model (2HDM) is analysed and a detailed study of the parameter space is presented, showing that flavour mixing in the 2HDM can be parametrized by various unitary matrices which arise from the misalignment in flavour space between pairs of various Hermitian flavour matrices which can be constructed within the model. This is entirely analogous to the generation of the CKM matrix in the Standard Model (SM). We construct weak basis invariants which can give insight into the physical implications of any flavour model, written in an arbitrary weak basis (WB) in the context of 2HDM. We apply this technique to two special cases, models with MFV and models with NNI structures. In both cases non-trivial CP-odd WB invariants arise in a mass power order much smaller than what one encounters in the SM, which can have important implications for baryogenesis in the framework of the general 2HDM.
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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 long-lived, multi-charged particles in pp collisions at root s=7 TeV using the ATLAS detector. Phys. Lett. B, 722(4-5), 305–323.
Abstract: A search for highly ionising, penetrating particles with electric charges from vertical bar q vertical bar = 2e to 6e is performed using the ATLAS detector at the CERN Large Hadron Collider. Proton-proton collision data taken at root s = 7 TeV during the 2011 running period, corresponding to an integrated luminosity of 4.4 fb(-1), are analysed. No signal candidates are observed, and 95% confidence level cross-section upper limits are interpreted as mass-exclusion lower limits for a simplified Drell-Yan production model. In this model, masses are excluded from 50 GeV up to 430, 480, 490, 470 and 420 GeV for charges 2e, 3e, 4e, 5e and 6e, respectively. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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