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Aceti, F., Bayar, M., Oset, E., Martinez Torres, A., Khemchandani, K. P., Dias, J. M., et al. (2014). Prediction of an I=1 D(D)over-bar* state and relationship to the claimed Z(c)(3900), Z(c)(3885). Phys. Rev. D, 90(1), 016003–13pp.
Abstract: We study here the interaction of D (D) over bar* in the isospin I = 1 channel in light of recent theoretical advances that allow us to combine elements of the local hidden gauge approach with heavy quark spin symmetry. We find that the exchange of light q (q) over bar is Okubo-Zweig-Iizuka (OZI) suppressed and thus we concentrate on the exchange of heavy vectors and of two pion exchange. The latter is found to be small compared to the exchange of heavy vectors, which then determines the strength of the interaction. A barely D (D) over bar* bound state decaying into eta(c)rho and pi J/psi is found. At the same time we reanalyze the data of the BESIII experiment on e(+)e(-) -> pi(+/-)(D (D) over bar*)(-/+), from where a Z(c)(3885) state was claimed, associated to a peak in the (D (D) over bar*)(-/+) invariant mass distribution close to threshold, and we find the data compatible with a resonance with mass around 3875 MeV and width around 30 MeV. We discuss the possibility that this and the Z(c)(3900) state found at BESIII, reconfirmed at 3894 MeV at Belle, or 3885 MeV at CLEO, could all be the same state and correspond to the one that we find theoretically.
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Albertus, C., Hernandez, E., & Nieves, J. (2014). B -> rho semileptonic decays and vertical bar V-ub vertical bar. Phys. Rev. D, 90(1), 013017–11pp.
Abstract: We reevaluate the B -> rho l(+) nu(l) decay width as a full B. pi pi iota(+)nu iota four-particle decay, in which the two final pions are produced via an intermediate. meson. The decay width can be written as a convolution of the B -> rho l(+) nu(l) decay width, for an off-shell., with the.. pp line shape. This allows us to fully incorporate the effects of the finite. meson width and a better comparison with actual experiments. We use an Omn s representation to provide the dependence of the B.. semileptonic form factors on q2. The Omn s subtraction constants and the overall normalization parameter jVubj are fitted to light cone sum rules and lattice QCD theoretical form-factor calculations, in the low and high q2 regions, respectively, together to the CLEO, BABAR, and Belle experimental partial branching fraction distributions. The extracted value from this global fit is jVubj d3.40 +/- 0.15_ x 10-3, in agreement with jVubj extracted using all other inputs in Cabibbo-Kobayashi-Maskawa fits and the exclusive semileptonic B. p channel, but showing a clear disagreement with jVubj extracted from inclusive semileptonic b. u decays. As estimated by [U.-G. Mei beta ner andW. Wang, J. High Energy Phys. 01 (2014) 107], taking into account the. meson width effects and the actual acceptance of the experiments is essential to render the jVubj determinations from exclusive B. p and B.. decays totally compatible.
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de Gouvea, A., Herrero-Garcia, J., & Kobach, A. (2014). Neutrino masses, grand unification, and baryon number violation. Phys. Rev. D, 90(1), 016011–11pp.
Abstract: If grand unification is real, searches for baryon-number violation should be included on the list of observables that may reveal information regarding the origin of neutrino masses. Making use of an effective-operator approach and assuming that nature is SU(5) invariant at very short distances, we estimate the consequences of different scenarios that lead to light Majorana neutrinos for low-energy phenomena that violate baryon number minus lepton number (B – L) by two (or more) units, including neutron-antineutron oscillations and B – L violating nucleon decays. We find that, among all possible effective theories of lepton-number violation that lead to nonzero neutrino masses, only a subset is, broadly speaking, consistent with grand unification.
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Pierre Auger Collaboration(Aab, A. et al), & Pastor, S. (2014). Muons in air showers at the Pierre Auger Observatory: Measurement of atmospheric production depth. Phys. Rev. D, 90(1), 012012–15pp.
Abstract: The surface detector array of the Pierre Auger Observatory provides information about the longitudinal development of the muonic component of extensive air showers. Using the timing information from the flash analog-to-digital converter traces of surface detectors far from the shower core, it is possible to reconstruct a muon production depth distribution. We characterize the goodness of this reconstruction for zenith angles around 60 degrees and different energies of the primary particle. From these distributions, we define X-max(mu) as the depth along the shower axis where the production of muons reaches maximum. We explore the potentiality of X-max(mu) as a useful observable to infer the mass composition of ultrahigh-energy cosmic rays. Likewise, we assess its ability to constrain hadronic interaction models.
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de Florian, D., Sassot, R., Epele, M., Hernandez-Pinto, R. J., & Stratmann, M. (2015). Parton-to-pion fragmentation reloaded. Phys. Rev. D, 91(1), 014035–17pp.
Abstract: We present a new, comprehensive global analysis of parton-to-pion fragmentation functions at next-to-leading-order accuracy in QCD. The obtained results are based on the latest experimental information on single-inclusive pion production in electron-positron annihilation, lepton-nucleon deep-inelastic scattering, and proton-proton collisions. An excellent description of all data sets is achieved, and the remaining uncertainties in parton-to-pion fragmentation functions are estimated based on the Hessian method. Extensive comparisons to the results from our previous global analysis are performed.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fernandez Martinez, P., Ferrer, A., et al. (2015). Search for new phenomena in events with a photon and missing transverse momentum in pp collisions at root s = 8 TeV with the ATLAS detector. Phys. Rev. D, 91(1), 012008–25pp.
Abstract: Results of a search for new phenomena in events with an energetic photon and large missing transverse momentum with the ATLAS experiment at the LHC are reported. Data were collected in proton-proton collisions at a center-of-mass energy of 8 TeVand correspond to an integrated luminosity of 20.3 fb(-1). The observed data are well described by the expected Standard Model backgrounds. The expected (observed) upper limit on the fiducial cross section for the production of events with a photon and large missing transverse momentum is 6.1 (5.3) fb at 95% confidence level. Exclusion limits are presented on models of new phenomena with large extra spatial dimensions, supersymmetric quarks, and direct pair production of dark-matter candidates.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2015). Measurements of Higgs boson production and couplings in the four-lepton channel in pp collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector. Phys. Rev. D, 91(1), 012006–47pp.
Abstract: The final ATLAS Run 1 measurements of Higgs boson production and couplings in the decay channel H -> ZZ* -> l(+)l(-)l(+)l'(-), where l, l' = e or mu, are presented. These measurements were performed using pp collision data corresponding to integrated luminosities of 4.5 and 20.3 fb(-1) at center-of-mass energies of 7 and 8 TeV, respectively, recorded with the ATLAS detector at the LHC. The H -> ZZ* -> 4l signal is observed with a significance of 8.1 standard deviations, with an expectation of 6.2 standard deviations, at m(H) = 125.36 GeV, the combined ATLAS measurement of the Higgs boson mass from the H -> gamma gamma and H -> ZZ* -> 4l channels. The production rate relative to the Standard Model expectation, the signal strength, is measured in four different production categories in the H -> ZZ* -> 4l channel. The measured signal strength, at this mass, and with all categories combined, is 1.44(-0.33)(+0.40). The signal strength for Higgs boson production in gluon fusion or in association with (tt) over bar or (bb) over bar pairs is found to be 1.7(-0.4)(+0.5), while the signal strength for vector-boson fusion combined with WH/ZH associated production is found to be 0.3(-0.9)(+1.6).
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2015). Study of B-+/-,B-0 -> J/psi(K+K-K +/-,0) and search for B-0 -> J/psi phi at BABAR. Phys. Rev. D, 91(1), 012003–12pp.
Abstract: We study the rare B meson decays B-+/-,B-0 -> J/psi(K+K-K +/-,0), B-+/-,B-0 -> J/psi phi K-+/-,K-0, and search for B-0 -> J/psi phi, using 469 x 10(6) B (B) over bar events collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II e(+)e(-) asymmetric energy collider. We present new measurements of branching fractions and a study of the J/psi phi mass distribution in search of new charmonium-like states. In addition, we search for the decay B-0 -> J/psi phi and find no evidence of a signal.
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Aristizabal Sierra, D., Staub, F., & Vicente, A. (2015). Shedding light on the b -> s anomalies with a dark sector. Phys. Rev. D, 92(1), 015001–11pp.
Abstract: The LHCb Collaboration has recently reported on some anomalies in b -> s transitions. In addition to discrepancies with the Standard Model (SM) predictions in some angular observables and branching ratios, an intriguing hint for lepton universality violation was found. Here we propose a simple model that extends the SM with a dark sector charged under an additional U(1) gauge symmetry. The spontaneous breaking of this symmetry gives rise to a massive Z' boson, which communicates the SM particles with a valid dark matter candidate, while solving the b -> s anomalies with contributions to the relevant observables.
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Fonseca, R. M., & Hirsch, M. (2015). SU(5)-inspired double beta decay. Phys. Rev. D, 92(1), 015014–14pp.
Abstract: The short-range part of the neutrinoless double beta amplitude is generated via the exchange of exotic particles, such as charged scalars, leptoquarks and/or diquarks. In order to give a sizable contribution to the total decay rate, the masses of these exotics should be of the order of (at most) a few TeV. Here, we argue that these exotics could be the “light” (i.e., weak-scale) remnants of some B – L violating variants of SU(5). We show that unification of the standard model gauge couplings, consistent with proton decay limits, can be achieved in such a setup without the need to introduce supersymmetry. Since these nonminimal SU(5)-inspired models violate B – L, they generate Majorana neutrino masses and therefore make it possible to explain neutrino oscillation data. The light colored particles of these models can potentially be observed at the LHC, and it might be possible to probe the origin of the neutrino masses with Delta L = 2 violating signals. As particular realizations of this idea, we present two models, one for each of the two possible tree-level topologies of neutrinoless double beta decay.
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