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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2017). Measurement of the inclusive electron spectrum from B meson decays and determination of vertical bar V-ub vertical bar. Phys. Rev. D, 95(7), 072001–23pp.
Abstract: Based on the full BABAR data sample of 466.5 million B (B) over bar pairs, we present measurements of the electron spectrum from semileptonic B meson decays. We fit the inclusive electron spectrum to distinguish Cabibbo-Kobayashi-Maskawa (CKM) suppressed B -> X(u)ev decays from the CKM-favored B -> X(u)ev decays, and from various other backgrounds, and determine the total semileptonic branching fraction B(B -> X(u)ev) = (10.34 +/- 0.04(stat) +/- 0.26(syst))%, averaged over B-+/- and B-0 mesons. We determine the spectrum and branching fraction for charmless B -> X(u)ev decays and extract the CKM element vertical bar V-ub vertical bar, by relying on four different QCD calculations based on the heavy quark expansion. While experimentally, the electron momentum region above 2.1 GeV/c is favored, because the background is relatively low, the uncertainties for the theoretical predictions are largest in the region near the kinematic endpoint. Detailed studies to assess the impact of these four predictions on the measurements of the electron spectrum, the branching fraction, and the extraction of the CKM matrix element vertical bar V-ub vertical bar are presented, with the lower limit on the electron momentum varied from 0.8 GeV/c to the kinematic endpoint. We determine V-ub vertical bar using each of these different calculations and find, vertical bar V-ub vertical bar = (3.794 +/- 0.107(exp) (+0.292)(-0.219) (SF) (+0.078)(-0.068)theory) x 10(-3) (De Fazio and Neubert), (4.563 +/- 0.126(exp) (+0.230)(+0.162)(-0.208)(-0.163)theory) x 10(-3) (Bosch, Lange, Neubert, and Paz), (3.959 +/- 0.104(exp -0.154)(SF-0.079)(+0.164)(+0.042) theory )x 10(-3) (Gambino, Giordano, Ossola, and Uraltsev), (3.848 +/- 0.108(exp -0.070)(theory)(+0.084)) x 10(-3) (dressed gluon exponentiation), where the stated uncertainties refer to the experimental uncertainties of the partial branching fraction measurement, the shape function parameters, and the theoretical calculations.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2013). Measurement of an excess of (B)over-bar -> D-(*) tau(-)(v)over-bar(tau) decays and implications for charged Higgs bosons. Phys. Rev. D, 88(7), 072012–30pp.
Abstract: Based on the full BABAR data sample, we report improved measurements of the ratios R(D) = B((B) over bar -> D tau(-)(v) over bar (tau))/B((B) over bar -> Dl(-)(v) over bar (l)) and R(D*) = B((B) over bar -> D*tau(-)(v) over bar (tau))/B((B) over bar -> D*l(-)(v) over bar (l)), where l refers to either an electron or muon. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D) = 0.440 +/- 0.058 +/- 0.042 and R(D*) = 0.332 +/- 0.024 +/- 0.018, which exceed the standard model expectations by 2.0 sigma and 2.7 sigma, respectively. Taken together, the results disagree with these expectations at the 3.4 sigma level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. Kinematic distributions presented here exclude large portions of the more general type III two-Higgs-doublet model, but there are solutions within this model compatible with the results.
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Restrepo, D., Taoso, M., Valle, J. W. F., & Zapata, O. (2012). Gravitino dark matter and neutrino masses with bilinear R-parity violation. Phys. Rev. D, 85(2), 023523–7pp.
Abstract: Bilinear R-parity violation provides an attractive origin for neutrino masses and mixings. In such schemes the gravitino is a viable decaying dark matter particle whose R-parity violating decays lead to monochromatic photons with rates accessible to astrophysical observations. We determine the parameter region allowed by gamma-ray line searches, dark matter relic abundance, and neutrino oscillation data, obtaining a limit on the gravitino mass m((G) over tilde) less than or similar to 1-10 GeV corresponding to a relatively low reheat temperature T-R less than or similar to few x 10(7)-10(8) GeV. Neutrino mass and mixing parameters may be reconstructed at accelerator experiments like the Large Hadron Collider.
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Anderson, P. R., Clark, R. D., Fabbri, A., & Good, M. R. R. (2019). Late time approach to Hawking radiation: Terms beyond leading order. Phys. Rev. D, 100(6), 061703–5pp.
Abstract: Black hole evaporation is studied using wave packets for the modes. These allow for approximate frequency and time resolution. The leading order late time behavior gives the well-known Hawking radiation that is independent of how the black hole formed. The focus here is on the higher order terms and the rate at which they damp at late times. Some of these terms carry information about how the black hole formed. A general argument is given which shows that the damping is significantly slower (power law) than what might be naively expected from a stationary phase approximation (exponential). This result is verified by numerical calculations in the cases of 2D and 4D black holes that form from the collapse of a null shell.
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Borexino Collaboration(Bellini, G. et al), & Pena-Garay, C. (2014). Final results of Borexino Phase-I on low-energy solar neutrino spectroscopy. Phys. Rev. D, 89(11), 112007–68pp.
Abstract: Borexino has been running since May 2007 at the Laboratori Nazionali del Gran Sasso laboratory in Italy with the primary goal of detecting solar neutrinos. The detector a large unsegmented liquid scintillator calorimeter characterized by unprecedented low levels of intrinsic radioactivity is optimized for the study of the lower energy part of the spectrum. During Phase-I (2007-2010) Borexino first detected and then precisely measured the flux of the Be-7 solar neutrinos ruled out any significant day-night asymmetry of their interaction rate made the first direct observation of the pep neutrinos and set the tightest upper limit on the flux of solar neutrinos produced in the CNO cycle (carbon nitrogen oxigen) where carbon nitrogen and oxygen serve as catalysts in the fusion process. In this paper we discuss the signal signature and provide a comprehensive description of the backgrounds quantify their event rates describe the methods for their identification selection or subtraction and describe data analysis. Key features are an extensive in situ calibration program using radioactive sources the detailed modeling of the detector response the ability to define an innermost fiducial volume with extremely low background via software cuts and the excellent pulse-shape discrimination capability of the scintillator that allows particle identification. We report a measurement of the annual modulation of the Be-7 neutrino interaction rate. The period the amplitude and the phase of the observed modulation are consistent with the solar origin of these events and the absence of their annual modulation is rejected with higher than 99% C.L. The physics implications of Phase-I results in the context of the neutrino oscillation physics and solar models are presented.
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Barenboim, G., Chun, E. J., Jung, S. H., & Park, W. I. (2014). Implications of an axino LSP for naturalness. Phys. Rev. D, 90(3), 035020–12pp.
Abstract: Both the naturalness of the electroweak symmetry breaking and the resolution of the strong CP problem may require a small Higgsino mass μgenerated by a realization of the DFSZ axion model. Assuming the axino is the lightest supersymmetric particle, we study its implications on μand the axion scale. Copiously produced light Higgsinos at collider (effectively only neutral next-to-lightest superparticles pairs) eventually decay to axinos leaving prompt multileptons or displaced vertices which are being looked for at the LHC. We use latest LHC7 + 8 results to derive current limits on μand the axion scale. Various Higgsino-axino phenomenology is illustrated by comparing with a standard case without lightest axinos as well as with a more general case with additional light gauginos in the spectrum.
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de Azcarraga, J. A., Kamimura, K., & Lukierski, J. (2011). Generalized cosmological term from Maxwell symmetries. Phys. Rev. D, 83(12), 124036–8pp.
Abstract: By gauging the Maxwell spacetime algebra, the standard geometric framework of Einstein gravity with cosmological constant term is extended by adding six four-vector fields A(mu)(ab)(x) associated with the six Abelian tensorial charges in the Maxwell algebra. In the simplest Maxwell extension of Einstein gravity this leads to a generalized cosmological term that includes a contribution from these vector fields. We also consider going beyond the basic gravitational model by means of bilinear actions for the new Abelian gauge fields. Finally, an analogy with the supersymmetric generalization of gravity is indicated. In an appendix, we propose an equivalent description of the model in terms of a shift of the standard spin connection by the A(mu)(ab)(x) fields.
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Dias, J. M., Toledo, G., Roca, L., & Oset, E. (2021). Unveiling the K-1(1270) double-pole structure in the (B)over-bar -> J/psi rho(K)over-bar and (B)over-bar -> J/psi(K)over-bar*pi decays. Phys. Rev. D, 103(11), 116019–13pp.
Abstract: By looking at the pseudoscalar-vector meson spectra in the (B) over bar -> J/psi rho(K) over bar and (B) over bar -> J/psi(K) over bar*pi weak decays, we theoretically investigate the double-pole structure of the K-1 (1270) resonance by using the chiral unitary approach to account for the final-state interactions between the pseudoscalar (P) and vector (V) mesons. The K-1 (1270) resonance is dynamically generated through these interactions in coupled channels and influences the shape of the invariant mass distributions under consideration. We show how these shapes are affected by the K-1 (1270) double-pole structure to confront the results from our model with future experiments that might investigate the PV spectra in these decays.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2015). Measurement of initial-state-final-state radiation interference in the processes e(+)e(-) -> mu(+)mu(-)gamma and e(+)e(-) -> pi(+)pi(-)gamma. Phys. Rev. D, 92(7), 072015–29pp.
Abstract: Charge asymmetry in the processes e(+)e(-) -> mu(+)mu(-)gamma and e(+)e(-) -> pi(+)pi(-)gamma is measured using 232 fb(-1) of data collected with the BABAR detector at e(+)e(-) center-of-mass energies near 10.58 GeV. An observable is introduced and shown to be very robust against detector asymmetries while keeping a large sensitivity to the physical charge asymmetry that results from the interference between initial-and final-state radiation (FSR). The asymmetry is determined as a function of the invariant mass of the final-state tracks from production threshold to a few GeV/c(2). It is compared to the expectation from QED for e(+)e(-) -> mu(+)mu(-)gamma, and from theoretical models for e(+)e(-) -> pi(+)pi(-)gamma. A clear interference pattern is observed in e(+)e(-) -> pi(+)pi(-)gamma, particularly in the vicinity of the f(2)(1270) resonance. The inferred rate of lowest-order FSR production is consistent with the QED expectation for e(+)e(-) -> mu(+)mu(-)gamma, and is negligibly small for e(+)e(-) -> pi(+)pi(-)gamma.
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Park, J. H. (2014). Lepton flavor violation from right-handed neutrino thresholds. Phys. Rev. D, 89(9), 095005–6pp.
Abstract: Charged lepton flavor violation is reappraised in the context of a supersymmetric seesaw mechanism. It is pointed out that a nontrivial flavor structure of right-handed neutrinos, whose effect has been thus far less studied, can give rise to significant slepton flavor transitions. Under the premise that the neutrino Yukawa couplings are of O(1), the right-handed neutrino mixing contribution could form a basis of the μ-> e gamma amplitude, which by itself might lead to an experimentally accessible rate, given a typical low-energy sparticle spectrum. Emphasis is placed on the crucial role of the recently measured lepton mixing angle theta(13) as well as the leptonic CP-violating phases.
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