Related papers: The Rare Decay D^0 -> gamma gamma

We present main results of the investigation of the rare decay mode D^0 -->gamma gamma, in which the long distance contributions are expected to be dominant. Using the Heavy Quark Chiral Lagrangian we have considered the anomaly…

We present a calculation of the rare decay modes D^0 -> e^+ e^- gamma and D^0 -> mu^+ mu^- gamma in the framework of Standard Model. For the short distance part, we have derived QCD corrections to the Wilson coefficients involved, including…

The weak radiative Cabibbo allowed decays D^+ -> anti K^0 pi^+ gamma and D^0 -> K^- pi^+ gamma with nonresonant K pi are investigated by relying on the factorization approximation for the nonleptonic weak transitions and the model which…

The short-distance contribution due to the $c\to u\gamma$ penguin as well as long-distance contributions are considered in an analysis of $D\to V\gamma$ decays, the latter being dominant. The matrix elements for nine $D\to V\gamma$…

We have observed the rare decay K+ --> pi+ mu+ mu- and measured the branching ratio Gamma(K+ --> pi+ mu+ mu-)/Gamma(K+ --> all) = (5.0 +/- 0.4 (stat.) +/- 0.7 (sys.) +/- 0.6 (theor.)) x 10^{-8}. We compare this result with predictions from…

The radiative B -> tau^+ tau^- gamma decay is investigated in the framework of the Standard Model. When only short (short and long together) distance contributions are taken into account, the Branching Ratio is found as 9.54x10^(-9)…

We evaluate the rare radiative kaon decays K_{L,S} -> 3 gamma. Applying the requirements of gauge invariance and Bose symmetry, we derive a general form of the decay amplitude, including both parity-conserving and parity-violating…

We present an analysis on the exclusive rare radiative decay modes Sigma_b->Sigma gamma and Xi_b->Xi gamma. The transition form factors which parameterize these processes are calculated using QCD light-cone sum rules. The decay widths we…

We present the estimate of the branching ratio for the rare decay $\bar B^0\to D^*\gamma$. We use QCD factorization approach in order to compute the amplitude of the process. The calculation is carried out with the leading order accuracy. %…

The recently observed mass difference of the $D^0-\overline{D^0}$ mixing is used to predict the branching ratios of the rare top quark decays $t\to u\gamma$ and $t\to ug$ in a model independent way using the effective Lagrangian approach.…

Using the most general, model independent form of the effective Hamiltonian rare decays (B -> l^+ l^- gamma (l=mu, tau)) are studied. The sensitivity of the photon energy distribution and branching ratio to the new Wilson coefficients is…

The radiative decays D^0 -> K^0(bar) P^0 gamma with nonresonant K^0(bar) P^0 (P^0 = pi^0, eta, eta') are considered within the framework which combines heavy quark effective theory and the chiral Lagrangian. Due to neutral mesons the…

We consider the rare decay $\eta\to\pi^0\pi^0\gamma\gamma$ and calculate the non-resonant contribution to the amplitude to one loop in Chiral Perturbation Theory. We display our result as both a diphoton energy spectrum and a partial decay…

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…

In this work, the radiative Bc -> D*_s gamma decay is investigated in the framework of QCD sum rules. The transition form factors responsible for the decay are calculated. The branching ratio for this decay is estimated to be order of 10^-5…

The rare decay B^+ \to D_s^+ \bar K^{*0} can occur only via annihilation diagrams in the Standard Model. We calculate the branching ratio in perturbative QCD approach based on k_T factorization theorem. We found that the branching ratio of…

The branching ratio for the rare two-body B_s -> rho gamma decay is calculated using the factorization assumption. This transition is dominated by the annihilation diagrams and, in principle, prone to receiving substantial contributions…

In many extensions of the standard model an additional up-like heavy quark appears. Its appearance induces flavour changing neutral current transition in the up-quark region at the tree level. We investigate possible effects of these models…

A class of meson decay modes sensitive to only one quark topology at leading G_F order (annihilation of valence quarks through a W) is described. No experimental observations, nor even upper limits, have been reported for these decays. This…

The various decay modes of the type $B \to \gamma D^* $ are dynamically different. In general there are factorizable contributions, and there are pole diagrams and pseudoscalar exchange contributions at meson level. The purpose of this…