Olmo, G. J., & Rubiera-Garcia, D. (2011). Palatini f(R) black holes in nonlinear electrodynamics. Phys. Rev. D, 84(12), 124059–14pp.
Abstract: The electrically charged Born-Infeld black holes in the Palatini formalism for f(R) theories are analyzed. Specifically we study those supported by a theory f(R) = R +/- R(2)/R(P), where R(P) is Planck's curvature. These black holes only differ from their General Relativity counterparts very close to the center but may give rise to different geometrical structures in terms of inner horizons. The nature and strength of the central singularities are also significantly affected. In particular, for the model f(R) = R – R(2)/R(P) the singularity is shifted to a finite radius, r(+), and the Kretschmann scalar diverges only as 1/(r-r(+))(2).
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Pierre Auger Collaboration(Abreu, P. et al), & Pastor, S. (2011). Search for ultrahigh energy neutrinos in highly inclined events at the Pierre Auger Observatory. Physical Review D, 84(12), 122005.
Abstract: The Surface Detector of the Pierre Auger Observatory is sensitive to neutrinos of all flavors above 0.1 EeV. These interact through charged and neutral currents in the atmosphere giving rise to extensive air showers. When interacting deeply in the atmosphere at nearly horizontal incidence, neutrinos can be distinguished from regular hadronic cosmic rays by the broad time structure of their shower signals in the water-Cherenkov detectors. In this paper we present for the first time an analysis based on down-going neutrinos. We describe the search procedure, the possible sources of background, the method to compute the exposure and the associated systematic uncertainties. No candidate neutrinos have been found in data collected from 1 January 2004 to 31 May 2010. Assuming an E(-2) differential energy spectrum the limit on the single-flavor neutrino is E(2)dN/dE < 1.74 x 10(-7)GeVcm(-2)s(-1)sr(-1) at 90% C.L. in the energy range 1 x 10(17) eV < E < 1 x 10(20)eV.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Measurement of the semileptonic branching fraction of the B(s) meson. Phys. Rev. D, 85(1), 011101–9pp.
Abstract: We report a measurement of the inclusive semileptonic branching fraction of the B(s) meson using data collected with the BABAR detector in the center-of-mass energy region above the Y(4S) resonance. We use the inclusive yield of phi mesons and the phi yield in association with a high-momentum lepton to perform a simultaneous measurement of the semileptonic branching fraction and the production rate of B(s) mesons relative to all B mesons as a function of center-of-mass energy. The inclusive semileptonic branching fraction of the B(s) meson is determined to be B(B(s) -> l nu X) = 9.5(-2.0)(+2.5)(stat)(-1.9)(+1.1)(syst)% where l indicates the average of e and mu.
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Azizi, K., Bayar, M., Ozpineci, A., Sarac, Y., & Sundu, H. (2012). Semileptonic transition of Sigma(b) to Sigma in light cone QCD sum rules. Phys. Rev. D, 85(1), 016002–8pp.
Abstract: We use distribution amplitudes of the light Sigma baryon and the most general form of the interpolating current for heavy Sigma(b) baryon to investigate the semileptonic Sigma(b) -> Sigma l(+)l(-) transition in light cone QCD sum rules. We calculate all 12 form factors responsible for this transition and use them to evaluate the branching ratio of the considered channel. The order of branching fraction shows that this channel can be detected at LHC.
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Dib, C., Helo, J. C., Hirsch, M., Kovalenko, S., & Schmidt, I. (2012). Heavy sterile neutrinos in tau decays and the MiniBooNE anomaly. Phys. Rev. D, 85(1), 011301–4pp.
Abstract: Current results of the MiniBooNE experiment show excess events that indicate neutrino oscillations, but only if one goes beyond the standard 3 family scenario. Recently a different explanation of the events has been given, not in terms of oscillations but by the production and decay of a massive sterile neutrino with large transition magnetic moment. We study the effect of such a sterile neutrino in the rare decays tau(-) -> mu(-)mu(+)pi(-)nu and tau(-) -> mu(-)mu(+)e(-)nu nu. We find that searches for these decays, featuring displaced vertices between the mu(-) and the other charged particles, constitute reliable tests for the existence of the sterile neutrino proposed to explain the MiniBooNE anomaly. These searches could be done with already existing experimental data.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., et al. (2012). K(s)(0) and Lambda production in pp interactions at root s=0.9 and 7 TeV measured with the ATLAS detector at the LHC. Phys. Rev. D, 85(1), 012001–28pp.
Abstract: The production of K(S)(0) and Lambda hadrons is studied in pp collision data at root s = 0.9 and 7 TeV collected with the ATLAS detector at the LHC using a minimum-bias trigger. The observed distributions of transverse momentum, rapidity, and multiplicity are corrected to hadron level in a model-independent way within well-defined phase-space regions. The distribution of the production ratio of (Lambda) over bar to Lambda baryons is also measured. The results are compared with various Monte Carlo simulation models. Although most of these models agree with data to within 15% in the K(S)(0) distributions, substantial disagreements are found in the Lambda distributions of transverse momentum.
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Cappiello, L., Cata, O., & D'Ambrosio, G. (2012). Holographic approach to low-energy weak interactions of mesons. Phys. Rev. D, 85(1), 015003–13pp.
Abstract: We apply the double-trace formalism to incorporate nonleptonic weak interactions of mesons into holographic models of the strong interactions. We focus our attention upon Delta S = 1 nonleptonic kaon decays. By working with a Yang-Mills-Chern-Simons 5-dimensional action, we explicitly show how, at low energies, one recovers the Delta S = 1 weak chiral Lagrangian for both the anomalous and nonanomalous sectors. We provide definite predictions for the low-energy coefficients in terms of the AdS metric and argue that the double-trace formalism is a 5-dimensional avatar of the Weak Deformation Model introduced long ago by Ecker et al. As a significant phenomenological application, we reassess the K -> 3 pi decays in the light of the holographic model. Previous models found a fine-tuned cancellation of resonance exchange in these decays, which was both conceptually puzzling and quantitatively in disagreement with experimental results. The holographic model we build is an illustrative counterexample showing that the cancellation encountered in the literature is not generic but a model-dependent statement and that agreement with experiment can be obtained.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Escobar, C., et al. (2012). Measurement of the isolated diphoton cross section in pp collisions at root s=7 TeV with the ATLAS detector. Phys. Rev. D, 85(1), 012003–28pp.
Abstract: The ATLAS experiment has measured the production cross section of events with two isolated photons in the final state, in proton-proton collisions at root s = 7 TeV. The full data set acquired in 2010 is used, corresponding to an integrated luminosity of 37 pb(-1). The background, consisting of hadronic jets and isolated electrons, is estimated with fully data-driven techniques and subtracted. The differential cross sections, as functions of the di-photon mass (m(gamma gamma)), total transverse momentum (p(T),(gamma gamma)), and azimuthal separation (Delta phi(gamma gamma)), are presented and compared to the predictions of next-to-leading-order QCD.
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Flynn, J. M., Hernandez, E., & Nieves, J. (2012). Triply heavy baryons and heavy quark spin symmetry. Phys. Rev. D, 85(1), 014012–10pp.
Abstract: We study the semileptonic b -> c decays of the lowest-lying triply heavy baryons made from b and c quarks in the limit m(b), m(c) >> Lambda(QCD) and close to the zero-recoil point. The separate heavy-quark spin symmetries strongly constrain the matrix elements, leading to single form factors for ccb -> ccc, bbc -> ccb, and bbb -> bbc baryon decays. We also study the effects on these systems of using a Y-shaped confinement potential, as suggested by lattice QCD results for the interaction between three static quarks.
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Pavon Valderrama, M., Xie, J. J., & Nieves, J. (2012). Are there three Xi (1950) states? Phys. Rev. D, 85(1), 017502–5pp.
Abstract: Different experiments on hadron spectroscopy have long suspected the existence of several cascade states in the 1900-2000 MeV region. They are usually labeled under the common name of Xi (1950). As we argue here, there are also theoretical reasons supporting the idea of several Xi (1950) resonances. In particular, we propose the existence of three Xi (1950) states: one of these states would be part of a spinparity 1/2(-) decuplet and the other two probably would belong to the 5/2(+) and 5/2(-) octets. We also identify which decay channels are more appropriate for the detection of each of the previous states.
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