119277218
Two-loop QCD correction to differential semi-leptonic b→u decays in the shape-function region
Abstract We calculate the two-loop QCD correction to the form factors of on-shell b -quark decay to an energetic massless quark, which constitutes the last missing piece required for an O ( α s 2 ) determination of | V u b | from inclusive semi-leptonic B ¯ → X u l ν ¯ decays in the shape-function region.
53695340
Exclusive radiative B-meson decays within the aligned two-Higgs-doublet model
A bstractIn the aligned two-Higgs-doublet model, the alignment of Yukawa matrices in flavour space guarantees the absence of tree-level flavour-changing neutral currents, while allowing at the same time for new sources of CP violation, implying potentially large effects in many low-energy processes. In this work we study the constraints from exclusive radiative B → V γ decays, where V denotes a light vector meson. The current experimental data on the CP-averaged branching ratios and the direct CP and isospin asymmetries are analyzed. It is found that, while the branching ratios and direct CP asymmetries do not constrain the parameter space much further compared to the inclusive B → Xs,d γ decays, complementary constraints can be obtained from the isospin asymmetries Δ(K*γ) and Δ(ργ). In addition, correlations between the various observables in exclusive B → V γ and inclusive B → Xs,d γ decays are investigated in detail, and predictions are made for several so far unmeasured observables.
118478034
NNLO vertex corrections to non-leptonic B decays: Tree amplitudes
Abstract The colour-suppressed tree amplitude in non-leptonic B decays is particularly sensitive to perturbative and non-perturbative corrections. We calculate the two-loop (NNLO) vertex corrections to the colour-suppressed and colour-allowed tree amplitudes in QCD factorization. Our results are given completely analytically, including the full dependence on the charm quark mass. We then update theoretical predictions for a range of interesting observables derived from ππ, πρ and ρρ final states that do not depend (significantly) on penguin contributions, and hence are now available with NNLO accuracy. We observe good agreement with experimental data within experimental and theoretical errors, except for observables involving the π 0 π 0 branching fraction.
119191019
The effects of a family non-universal Z-prime boson on B--->pipi decays
Motivated by the measured large branching ratio of (the so-called ππ puzzle), we investigate the effects of a family nonuniversal Z′ model on the tree-dominated B → ππ decays. We find that the Z′ coupling parameter with a nontrivial new weak phase , which is relevant to the Z′ contributions to the QCD penguin sector △C5, is needed to reconcile the observed discrepancy. Combined with the recent fitting results from B → πK, πK* and ρK decays, the Z′ parameter spaces are severely reduced but still not excluded entirely, implying that both the "ππ" and "πK" puzzles could be accommodated simultaneously within such a family nonuniversal Z′ model.
1941882
Reexamining charmless B ---> PV decays in QCD factorization approach
Using the QCD factorization approach, we reexamine the two-body hadronic charmless $B$-meson decays to final states involving a pseudoscalar~($P$) and a vector~($V$) meson, with inclusion of the penguin contractions of spectator-scattering amplitudes induced by the $b\to D g^\ast g^\ast$~(where $D=d$ or $s$, and $g^\ast$ denotes an off-shell gluon) transitions, which are of order $\alpha_s^2$. Their impacts on the CP-averaged branching ratios and CP-violating asymmetries are examined. We find that these higher order penguin contraction contributions have significant impacts on some specific decay modes. Since $B\to \pi K^{\ast}$, $K \rho$ decays involve the same electro-weak physics as $B\to \pi K$ puzzles, we present a detailed analysis of these decays and find that the five R-ratios for $B\to \pi K^{\ast}$, $K \rho$ system are in agreement with experimental data except for $R(\pi K^*)$. Generally, these new contributions are found to be important for penguin-dominated $B\to PV$ decays.
125172218
Charmless anti-B(s) ---> VV decays in QCD factorization
98875889
Isospin dependent global neutronnucleus optical model potential
Abstract In this paper, we construct a new phenomenological isospin dependent global neutron–nucleus optical model potential. Based on the existing experimental data of elastic scattering angular distributions for neutron as projectile, we obtain a set of the isospin dependent global neutron–nucleus optical model potential parameters, which can basically reproduce the experimental data for target nuclei from 24 Mg to 242 Pu with the energy region up to 200 MeV.
54218524
Quadrupole-octopole alignment of CMB related to the primordial power spectrum with dipolar modulation in anisotropic spacetime
The WMAP and Planck observations show that the quadrupole and octopole orientations of the CMB might align with each other. We reveal that the quadrupole-octopole alignment is a natural implication of the primordial power spectrum in an anisotropic spacetime. The primordial power spectrum is presented with a dipolar modulation. We obtain the privileged plane by employing the "power tensor" technique. At this plane, there is maximum correlation between quadrupole and octopole. The probability for the alignment is much larger than that in the isotropic universe. We find that this model would lead to deviations from the statistical isotropy only for low-e multipoles.
119265455
Symmetry, causal structure and superluminality in Finsler spacetime
The superluminal behaviors of neutrinos were reported by the OPERA collaboration recently. It was also noticed by Cohen and Glashow that, in standard quantum field theory, the superluminal neutrinos would lose their energy via the Cherenkov-like process rapidly. Finslerian special relativity may provide a framework to cooperate with the OPERA neutrino superluminality without Cherenkov-like process. We present clearly the symmetry, causal structure and superluminality in Finsler spacetime. The principle of relativity and the causal law are preserved. The energy and momentum are well defined and conserved in Finslerian special relativity. The Cherenkov-like process is proved to be forbidden kinematically and the superluminal neutrinos would not lose energy in their distant propagations from CERN to the Gran Sasso Laboratory. The energy dependence of neutrino superluminality is studied based on the reported data of the OPERA collaboration as well as other groups.
118442016
Extracting the nuclear symmetry potential and energy from neutron-nucleus scattering data
Abstract According to the Hugenholtz–Van Hove theorem, the symmetry energy and its density slope can be decomposed uniquely in terms of the single-nucleon potential in asymmetric nuclear matter which, at normal density, can be constrained by the nucleon optical model potential extracted from analyzing the nucleon–nucleus scattering data. To more accurately extract information on the symmetry energy and its density slope at normal density from neutron–nucleus scattering data, going beyond the well-known Lane potential, we include consistently the second-order terms in isospin asymmetry in both the optical model potential and the symmetry energy decomposition. We find that the strength of the second-order symmetry potential U sym , 2 in asymmetric nuclear matter is significant compared to the first-order one U sym , 1 , especially at high nucleon momentum. While the U sym , 1 at normal density decreases with nucleon momentum, the U sym , 2 is found to have the opposite behavior. Moreover, we discuss effects of the U sym , 1 and U sym , 2 on determining the density dependence of the symmetry energy, and we find that the available neutron–nucleus scattering data favor a softer density dependence of the symmetry energy at normal density with a negligible contribution from the U sym , 2 .
118861755
Constraints from Type IA Supernovae on {\lambda}-CDM Model in Randers-Finsler Space
Abstract Gravitational field equations in Randers-Finsler space of approximate Berwald type are investigated. A modified Friedmann equation and a new luminosity distance-redshift relation is proposed. A best-fit to the Type Ia supernovae (SNe) observations yields that the ΩΛ in the Λ-CDM model is suppressed to almost zero. This fact indicates that the astronomical observations on the Type Ia SNe can be described well without invoking any form of dark energy. The best-fit age of the universe is given. It is in agreement with the age of our galaxy.