Martinez Torres, A., Khemchandani, K. P., Nielsen, M., Navarra, F. S., & Oset, E. (2013). Exploring the D* rho system within QCD sum rules. Phys. Rev. D, 88(7), 074033–14pp.
Abstract: We present a study of the D* rho system made by using the method of QCD sum rules to determine the mass of possible resonances generated in the same system. Using isospin and spin projectors, we investigate the different configurations and obtain evidences for three D* mesons with isospin I = 1/2, spin S = 0, 1, 2 and with masses 2500 +/- 67, 2523 +/- 60, and 2439 +/- 119 MeV, respectively. The last state can be associated with D-2*(2460) ( spin 2) listed by the Particle Data Group, while one of the first two might be related to D* (2640), with unknown spin parity. In the case of I = 3/2 we also find evidences of three states with spin 0, 1, and 2, respectively, with masses 2467 +/- 82, 2420 +/- 128, and 2550 +/- 56 MeV. The results for the sector I = 1/2 and S 0, 1, 2, are intriguingly similar to a previous study of the D* rho system based on effective field theories, supporting in this way a molecular picture for the resonances D* (2640) and D-2* (2460), while the results for I = 3/2 hint towards the existence of exotic mesons since a multiquark configuration is required to get the quantum numbers of the states found.
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Volpe, C., Vaananen, D., & Espinoza, C. (2013). Extended evolution equations for neutrino propagation in astrophysical and cosmological environments. Phys. Rev. D, 87(11), 113010–17pp.
Abstract: We derive the evolution equations for a system of neutrinos interacting among themselves and with a matter background, based upon the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy. This theoretical framework gives an (unclosed) set of first-order coupled integro-differential equations governing the evolution of the reduced density matrices. By employing the hierarchy, we first rederive the mean-field evolution equations for the neutrino one-body density matrix associated with a system of neutrinos and antineutrinos interacting with matter and with an anisotropic neutrino background. Then, we derive extended evolution equations to determine neutrino flavor conversion beyond the commonly used mean-field approximation. To this aim we include neutrino-antineutrino pairing correlations to the two-body density matrix. The inclusion of these new contributions leads to an extended evolution equation for the normal neutrino density and to an equation for the abnormal one involving the pairing mean field. We discuss the possible impact of neutrino-antineutrino correlations on neutrino flavor conversion in the astrophysical and cosmological environments, and possibly upon the supernova dynamics. Our results can be easily generalized to an arbitrary number of neutrino families.
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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). First Measurement of the CP-Violating Phase in B-s(0) -> phi phi Decays. Phys. Rev. Lett., 110(24), 241802–8pp.
Abstract: A first flavor-tagged measurement of the time-dependent CP-violating asymmetry in B-s(0) -> phi phi decays is presented. In this decay channel, the CP-violating weak phase arises due to CP violation in the interference between B-s(0)-(B) over bar (0)(s) mixing and the b -> s (s) over bars gluonic penguin decay amplitude. Using a sample of pp collision data corresponding to an integrated luminosity of 1.0 fb(-1) and collected at a center-of-mass energy of 7 TeV with the LHCb detector, 880 B-s(0) -> phi phi signal decays are obtained. The CP-violating phase is measured to be in the interval [-2.46, -0.76] rad at a 68% confidence level. The p value of the standard model prediction is 16%.
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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). First Observation of CP Violation in the Decays of B-s(0) Mesons. Phys. Rev. Lett., 110(22), 221601–9pp.
Abstract: Using pp collision data corresponding to an integrated luminosity of 1.0 fb(-1) and collected by LHCb in 2011 at a center-of-mass energy of 7 TeV, we report the measurement of direct CP violation in B-s(0) -> K-pi(+) decays, A(CP) (B-s(0) -> K-pi(+)) = 0.27 +/- 0.04(stat) +/- 0.01(syst), with significance exceeding 5 standard deviations. This is the first observation of CP violation in the decays of B-s(0) mesons. Furthermore, we provide an improved determination of direct CP violation in B-0 -> K+pi(-) decays, A(CP)(B-0 -> K+pi(-) ) = -0.080 +/- 0.007(stat) +/- 0.003(syst), which is the most precise measurement of this quantity to date.
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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). First observations of (B)over-bar(s)(0) -> D+D-, Ds+D- and D-0(D)over-bar(0) decays. Phys. Rev. D, 87(9), 092007–12pp.
Abstract: First observations and measurements of the branching fractions of the (B) over bar (0)(s) -> D+D-, (B) over bar (0)(s) -> Ds+D- and (B) over bar (0)(s) -> D-0(D) over bar (0) decays are presented using 1.0 fb(-1) of data collected by the LHCb experiment. These branching fractions are normalized to those of (B) over bar (0) -> D+D-, B-0 -> D-Ds+ and B- -> (DDs-)-D-0, respectively. An excess of events consistent with the decay (B) over bar (0) -> D-0(D) over bar (0) is also seen, and its branching fraction is measured relative to that of B- -> D0Ds-. Improved measurements of the branching fractions B((B) over bar (0)(s) -> Ds+Ds-) and B(B- -> (DDs-)-D-0) are reported, each relative to B(B-0 -> D-Ds+). The ratios of branching fractions are B((B) over bar (0)(s) -> D+D-)/B((B) over bar (0) -> D+D-) = 1.08 +/- 0.20 +/- 0.10, B((B) over bar (0)(s) -> Ds+D-)/B(B-0 -> D-Ds+) = 0.050 +/- 0.008 +/- 0.004, B((B) over bar (0)(s) -> D-0(D) over bar (0))/B((B) over bar (-) -> (DDs-)-D-0) = 0.019 +/- 0.003 +/- 0.003, B((B) over bar (0) -> D-0(D) over bar (0))/B(B- -> (DDs-)-D-0) < 0.0024 at 90% CL, B(<(B)over bar>(0)(s) -> D-s(+)(D) over bar (-)(s))/B(B-0 -> D-Ds+) = 0.56 +/- 0.03 +/- 0.04, B(B -> (DDs)-D-0)/B(B-0 -> D-Ds+) = 1.22 +/- 0.02 +/- 0.07, where the uncertainties are statistical and systematic, respectively.
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ANTARES Collaboration(Adrian-Martinez, S. et al), Bigongiari, C., Emanuele, U., Gomez-Gonzalez, J. P., Hernandez-Rey, J. J., Lambard, G., et al. (2013). First results on dark matter annihilation in the Sun using the ANTARES neutrino telescope. J. Cosmol. Astropart. Phys., 11(11), 032–22pp.
Abstract: A search for high-energy neutrinos coming from the direction of the Sun has been performed using the data recorded by the ANTARES neutrino telescope during 2007 and 2008. The neutrino selection criteria have been chosen to maximize the selection of possible signals produced by the self-annihilation of weakly interacting massive particles accumulated in the centre of the Sun with respect to the atmospheric background. After data unblinding, the number of neutrinos observed towards the Sun was found to be compatible with background expectations. The 90% CL upper limits in terms of spin-dependent and spin-independent WIMP-proton cross-sections are derived and compared to predictions of two supersymmetric models, CMSSM and MSSM-7. The ANTARES limits are comparable with those obtained by other neutrino observatories and are more stringent than those obtained by direct search experiments for the spin-dependent WIMP-proton cross-section in the case of hard self-annihilation channels (W+W-, tau(+)tau(-)).
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ANTARES Collaboration(Adrian-Martinez, S. et al), Bigongiari, C., Emanuele, U., Gomez-Gonzalez, J. P., Hernandez-Rey, J. J., Lambard, G., et al. (2013). First search for neutrinos in correlation with gamma-ray bursts with the ANTARES neutrino telescope. J. Cosmol. Astropart. Phys., 03(3), 006–16pp.
Abstract: A search for neutrino-induced muons in correlation with a selection of 40 gamma-ray bursts that occurred in 2007 has been performed with the ANTARES neutrino telescope. During that period, the detector consisted of 5 detection lines. The ANTARES neutrino telescope is sensitive to TeV-PeV neutrinos that are predicted from gamma-ray bursts. No events were found in correlation with the prompt photon emission of the gamma-ray bursts and upper limits have been placed on the flux and fluence of neutrinos for different models.
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Felipe, R. G., Joaquim, F. R., & Serodio, H. (2013). Flavored CP asymmetries for type II seesaw leptogenesis. Int. J. Mod. Phys. A, 28(31), 1350165–13pp.
Abstract: A novel contribution to the leptonic CP asymmetries in type II seesaw leptogenesis scenarios is obtained for the cases in which flavor effects are relevant for the dynamics of leptogenesis. In the so-called flavored leptogenesis regime, the interference between the tree-level amplitude of the scalar triplet decaying into two leptons and the one-loop wave function correction with leptons in the loop, leads to a new nonvanishing CP asymmetry contribution. The latter conserves total lepton number but violates lepton flavor. Cases in which this novel contribution may be dominant in the generation of the baryon asymmetry are briefly discussed.
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Aplin, S., Boronat, M., Dannheim, D., Duarte, J., Gaede, F., Ruiz-Jimeno, A., et al. (2013). Forward tracking at the next e(+)e(-) collider part II: experimental challenges and detector design. J. Instrum., 8, T06001–26pp.
Abstract: We present the second in a series of studies into the forward tracking system for a future linear e(+)e(-) collider with a center-of-mass energy in the range from 250 GeV to 3 TeV. In this note a number of specific challenges are investigated, which have caused a degradation of the tracking and vertexing performance in the forward region in previous experiments. We perform a quantitative analysis of the dependence of the tracking performance on detector design parameters and identify several ways to mitigate the performance loss for charged particles emitted at shallow angle.
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Malinsky, M. (2013). Fun with the Abelian Higgs model. Eur. Phys. J. C, 73(5), 2415–12pp.
Abstract: In calculations of the elementary scalar spectra of spontaneously broken gauge theories there are a number of subtleties which, though it is often unnecessary to deal with them in the order-of-magnitude type of calculations, have to be taken into account if fully consistent results are sought for. Within the “canonical” effective-potential approach these are, for instance: the need to handle infinite series of nested commutators of derivatives of field-dependent mass matrices, the need to cope with spurious IR divergences emerging in the consistent leading-order approximation and, in particular, the need to account for the fine interplay between the renormalization effects in the one-and two-point Green functions which, indeed, is essential for the proper stable vacuum identification and, thus, for the correct interpretation of the results. In this note we illustrate some of these issues in the realm of the minimal Abelian Higgs model and two of its simplest extensions including extra heavy scalars in the spectrum in attempt to exemplify the key aspects of the usual “hierarchy problem” lore in a very specific and simple setting. We emphasize that, regardless of the omnipresent polynomial cut-off dependence in the one-loop corrections to the scalar two-point function, the physical Higgs boson mass is always governed by the associated symmetry-breaking VEV and, as such, it is generally as UV-robust as all other VEV-driven masses in the theory.
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