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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) -> Ds+Ds- Decays. Phys. Rev. Lett., 113(21), 211801–9pp.
Abstract: We present a measurement of the CP-violating weak mixing phase phi(s) using the decay (B) over bar (0)(s) -> Ds+Ds- in a data sample corresponding to 3.0 fb(-1) of integrated luminosity collected with the LHCb detector in pp collisions at center-of-mass energies of 7 and 8 TeV. An analysis of the time evolution of the system, which does not use the constraint vertical bar lambda vertical bar = 1 to allow for the presence of CP violation in decay, yields phi(s) = 0.02 +/- 0.17(stat) +/- 0.02(syst) rad, vertical bar lambda vertical bar = 0.91(-0.15)(+0.18)(stat) +/- 0.02(syst). This result is consistent with the standard model expectation.
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Carrasco, N., Ciuchini, M., Dimopoulos, P., Frezzotti, R., Gimenez, V., Herdoiza, G., et al. (2014). B-physics from N-f=2 tmQCD: the Standard Model and beyond. J. High Energy Phys., 03(3), 016–52pp.
Abstract: We present a lattice QCD computation of the b-quark mass, the B and B-s decay constants, the B-mixing bag parameters for the full four-fermion operator basis as well as determinations for xi and f(Bq) root B-i((q)) extrapolated to the continuum limit and to the physical pion mass. We used N-f = 2 twisted mass Wilson fermions at four values of the lattice spacing with pion masses ranging from 280 to 500 MeV. Extrapolation in the heavy quark mass from the charm to the bottom quark region has been carried out on ratios of physical quantities computed at nearby quark masses, exploiting the fact that they have an exactly known infinite mass limit. Our results are m(b)(m(b), (MS) over bar) = 4.29(12) GeV, f(Bs) = 228(8) MeV, f(B) = 189(8) MeV and f(Bs)/f(B) = 1.206(24). Moreover with our results for the bag-parameters we find xi = 1.225(31), B-1((s))/B-1((d)) = 1.01(2), f (Bd) root(B) over cap ((d))(1) = 216(10) MeV and integral Bs root(B) over cap ((s))(1) = 262(10) MeV. We also computed the bag parameters for the complete basis of the four-fermion operators which are required in beyond the SM theories. By using these results for the bag parameters we are able to provide a refined Unitarity Triangle analysis in the presence of New Physics, improving the bounds coming from B-(s) -(B) over bar ((s)) mixing.
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Carrasco, N., Deuzeman, A., Dimopoulos, P., Frezzotti, R., Gimenez, V., Herdoiza, G., et al. (2014). Up, down, strange and charm quark masses with N-f=2+1+1 twisted mass lattice QCD. Nucl. Phys. B, 887, 19–68.
Abstract: We present a lattice QCD calculation of the up, down, strange and charm quark masses performed using the gauge configurations produced by the European Twisted Mass Collaboration with N-f = 2 + 1 + 1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their physical values. The simulations are based on a unitary setup for the two light quarks and on a mixed action approach for the strange and charm quarks. The analysis uses data at three values of the lattice spacing and pion masses in the range 210-450 MeV, allowing for accurate continuum limit and controlled chiral extrapolation. The quark mass renormalization is carried out non-perturbatively using the RI'-MOM method. The results for the quark masses converted to the (MS) over bar scheme are: m(ud) (2 GeV) = 3.70(17) MeV, m(s)(2 GeV) = 99.6(4.3) MeV and m(c)(m(c)) = 1.348(46) GeV. We obtain also the quark mass ratios m(s)/m(ud) = 26.66(32) and m(c)/m(s) = 11.62(16). By studying the mass splitting between the neutral and charged kaons and using available lattice results for the electromagnetic contributions, we evaluate m(u)/m(d) = 0.470(56), leading to m(u) = 2.36(24) MeV and m(d) = 5.03(26) MeV.
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Bernardoni, F., Blossier, B., Bulava, J., Della Morte, M., Fritzsch, P., Garron, N., et al. (2014). Decay constants of B-mesons from non-perturbative HQET with two light dynamical quarks. Phys. Lett. B, 735, 349–356.
Abstract: We present a computation of B-meson decay constants from lattice QCD simulations within the framework of Heavy Quark Effective Theory for the b-quark. The next-to-leading order corrections in the HQET expansion are included non-perturbatively. Based on N-f = 2 gauge field ensembles, covering three lattice spacings a approximate to (0.08-0.05) fm and pion masses down to 190 MeV, a variational method for extracting hadronic matrix elements is used to keep systematic errors under control. In addition we perform a careful autocorrelation analysis in the extrapolation to the continuum and to the physical pion mass limits. Our final results read f(B) = 186(13) MeV, f(Bs) = 224(14) MeV and f(Bs)/f(B) = 1.203(65). A comparison with other results in the literature does not reveal a dependence on the number of dynamical quarks, and effects from truncating HQET appear to be negligible.
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Valcarce, A., Garcilazo, H., & Vijande, J. (2014). Heavy baryon spectroscopy with relativistic kinematics. Phys. Lett. B, 733, 288–295.
Abstract: We present a comparative Faddeev study of heavy baryon spectroscopy with nonrelativistic and relativistic kinematics. We show results for different standard hyperfine interactions with both kinematics in an attempt to learn about the light quark dynamics. We highlight the properties of particular states accessible in nowadays laboratories that would help in discriminating between different dynamical models. The advance in the knowledge of light quark dynamics is a key tool for the understanding of the existence of exotic hadrons.
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Campanario, F., Kerner, M., Ninh, D. L., & Zeppenfeld, D. (2014). Next-to-leading order QCD corrections to ZZ production in association with two jets. J. High Energy Phys., 07(7), 148–14pp.
Abstract: We present a calculation of next-to-leading order QCD corrections to QCD-induced ZZ production in association with two jets at hadron colliders. Both Z bosons decay leptonically with all off-shell effects, virtual photon contributions and spin-correlation effects fully taken into account. This process is an important background to weak boson scattering and to searches for signals of new physics beyond the Standard Model. As expected, the next-to-leading order corrections reduce significantly the scale uncertainty and show a non-trivial phase space dependence in kinematic distributions. Our code will be publicly available as part of the parton level Monte Carlo program VBFNLO.
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Cabrera, M. E., Casas, A., Ruiz de Austri, R., & Bertone, G. (2014). LHC and dark matter phenomenology of the NUGHM. J. High Energy Phys., 12(12), 114–39pp.
Abstract: We present a Bayesian analysis of the NUGHM, a supersymmetric scenario with non-universal gaugino masses and Higgs masses, including all the relevant experimental observables and dark matter constraints. The main merit of the NUGHM is that it essentially includes all the possibilities for dark matter (DM) candidates within the MSSM, since the neutralino and chargino spectrum -and composition- are as free as they can be in the general MSSM. We identify the most probable regions in the NUHGM parameter space, and study the associated phenomenology at the LHC and the prospects for DM direct detection. Requiring that the neutralino makes all of the DM in the Universe, we identify two preferred regions around m(chi 10) = 1 TeV, 3 TeV, which correspond to the (almost) pure Higgsino and wino case. There exist other marginal regions (e.g. Higgs-funnel), but with much less statistical weight. The prospects for detection at the LHC in this case are quite pessimistic, but future direct detection experiments like LUX and XENON1T, will be able to probe this scenario. In contrast, when allowing other DM components, the prospects for detection at the LHC become more encouraging – the most promising signals being, beside the production of gluinos and squarks, the production of the heavier chargino and neutralino states, which lead to WZ and same-sign WW final states – and direct detection remains a complementary, and even more powerful, way to probe the scenario.
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Agullo, I., Landete, A., & Navarro-Salas, J. (2014). Electric-magnetic duality and renormalization in curved spacetimes. Phys. Rev. D, 90(12), 124067–7pp.
Abstract: We point out that the duality symmetry of free electromagnetism does not hold in the quantum theory if an arbitrary classical gravitational background is present. The symmetry breaks in the process of renormalization, as also happens with conformal invariance. We show that a similar duality anomaly appears for a massless scalar field in 1 + 1 dimensions.
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Olmo, G. J., & Rubiera-Garcia, D. (2014). Semiclassical geons at particle accelerators. J. Cosmol. Astropart. Phys., 02(2), 010–25pp.
Abstract: We point out that in certain four-dimensional extensions of general relativity constructed within the Palatini formalism stable self-gravitating objects with a discrete mass and charge spectrum may exist. The incorporation of nonlinearities in the electromagnetic field may effectively reduce their mass spectrum by many orders of magnitude. As a consequence, these objects could be within (or near) the reach of current particle accelerators. We provide an exactly solvable model to support this idea.
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Di Mauro, M., Donato, F., Fornengo, N., Lineros, R. A., & Vittino, A. (2014). Interpretation of AMS-02 electrons and positrons data. J. Cosmol. Astropart. Phys., 04(4), 006–33pp.
Abstract: We perform a combined analysis of the recent AMS-02 data on electrons, positrons, electrons plus positrons and positron fraction, in a self-consistent framework where we realize a theoretical modeling of all the astrophysical components that can contribute to the observed fluxes in the whole energy range. The primary electron contribution is modeled through the sum of an average flux from distant sources and the fluxes from the local supernova remnants in the Green catalog. The secondary electron and positron fluxes originate from interactions on the interstellar medium of primary cosmic rays, for which we derive a novel determination by using AMS-02 proton and helium data. Primary positrons and electrons from pulsar wind nebulae in the ATNF catalog are included and studied in terms of their most significant (while loosely known) properties and under different assumptions (average contribution from the whole catalog, single dominant pulsar, a few dominant pulsars). We obtain a remarkable agreement between our various modeling and the AMS-02 data for all types of analysis, demonstrating that the whole AMS-02 leptonic data admit a self-consistent interpretation in terms of astrophysical contributions.
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