Related papers: Uncertainties from Long Range Effects in $B \to K^…
We compute long distance effects on the photon energy spectrum in inclusive radiative decays of $B$ mesons using light-cone expansion and heavy quark effective theory. We show that for sufficiently high photon energy the leading…
BL Lacertae objects are an extreme subclass of AGNs showing rapid and large-amplitude variability, high and variable polarization, and core-dominated radio emissions. If a strong beaming effect is the cause of the extreme observation…
We study the radiative decay B -> gamma l nu_l in the framework of QCD factorization. We demonstrate explicitly that, in the heavy-quark limit and at one-loop order in perturbation theory, the amplitude does factorize, i.e. that it can be…
We reexamine the invariance of two-photon transition matrix elements and corresponding two-photon Rabi frequencies under the "gauge" transformation from the length to the velocity gauge. It is shown that gauge invariance, in the most…
We present a unified general formalism for ultraviolet Lorentz invariance violation (LV) testing through electromagnetic wave propagation, based on both dispersion and rotation measure data. This allows for a direct comparison of the…
We calculate the leading-order matrix element for the decay $B \to K^* \gamma$ in the quenched approximation of lattice QCD on a $24^3 \times 48$ lattice at $\beta=6.2$, using an O(a)-improved fermion action. Extrapolating the quark masses…
In $B \to X_s \gamma $ there are perturbative $QCD$ corrections at order $\alpha_s$ not only to the single quark line process $ b \to s \gamma$ but also coming from a set of diagrams where the weak interaction vertex involves a gluon which…
We study a vector dominance model which predicts a fairly large number of currently interesting decay amplitudes of the types S -> \gamma \gamma, V -> S \gamma and S -> V \gamma, where S and V denote scalar and vector mesons, in terms of…
The b --> s gamma transition proceeds by a loop ``penguin'' diagram. It may be used to measure precisely the couplings of the top quark and to search for the effects of any new particles appearing in the loop. We present a preliminary…
The shape of the lepton spectrum in inclusive semileptonic $B\to X\,\ell\,\bar\nu_\ell$ decay is sensitive to matrix elements of the heavy quark effective theory, $\bar\Lambda$ and $\lambda_1$. From CLEO data we extract…
We present a full calculation of the amplitudes for $B_{d[s]} \to \gamma \gamma$ in a simple ACD model that extends an incomplete one in a previous paper. We find cancellations between the contributions from different KK towers and a small…
Adiabatic perturbations in the cosmology of a quintessential scalar field with exponential potential gravitationally coupled to radiation/matter are investigated in a gauge invariant formalism. The main question addressed in this paper is…
We study changes in the $\gamma$--ray intensity at very high energies observed from the $\gamma$--ray binary HESS J0632+057. Publicly available data collected by Cherenkov telescopes were examined by means of a simple method utilizing…
In modified gravity theories, the gravitational waves propagation are presented in nonstandard ways. We consider a friction term different from GR and constrain the modified gravitational waves propagation from observations. The modified…
One of the experimental tests of Lorentz invariance violation is to measure the helicity dependence of the propagation velocity of photons originating in distant cosmological obejcts. Using a recent determination of the distance of the…
Using a QCD relativistic potential model, previously applied to the calculation of the heavy meson leptonic constants, we evaluate the form factors governing the exclusive decays $B\to\rho\ell\nu$, $B\to K^*\gamma$ and $B\to…
We study the radiative leptonic $B_c\to \gamma\ell\bar\nu$ decays in the nonrelativistic QCD effective field theory, and consider a fast-moving photon. As a result the interactions with the heavy quarks can be integrated out, and thus we…
A sizable right-handed photon polarization in $b\to s\gamma$ is a clear signal for new physics. In this work we point out that the photon helicity in $b\to s\gamma$ can be unambiguously extracted by combining the measurements in $B\to…
Motivated by a recent Belle~II measurement that suggests an excess in the rare decay $B \to K\, E_{\rm miss}$, and building upon our recent differential decay rate likelihood analysis of the existing experimental information, we investigate…
In the paper, we apply the $k_T$ factorization approach to deal with the $B\to K$ transition form factor with tensor current in the large recoil regions. Main uncertainties for the estimation are discussed and we obtain $F_T^{B\to…