Related papers: The $c \to u \gamma$ Contribution to Weak Radiativ…
The charmless $B_{c}$ $\to$ $PP$, $PV$~(where $P$ and $V$ denote the light pseudoscalar and vector mesons, respectively) decays can occur only via the weak annihilation diagrams within the Standard Model and provide, therefore, an ideal…
We show that the presence of intrinsic charm in the hadrons' light-cone wave functions, even at a few percent level, provides new, competitive decay mechanisms for B decays which are nominally CKM-suppressed. For example, the weak decays of…
We evaluate the branching ratios of the radiative decays $B \to K^* \gamma $, and $B \to K_1 \gamma $ in the framework of three-point function QCD sum rules. We find: $ \Gamma(B \to K^* \gamma) / \Gamma(b \to s \gamma) = 0.17 \pm 0.05$ and…
We report on the progress of our ongoing project to quantify the role of the charm quark in the non-leptonic decay of a kaon into two pions. The effect of its associated mass scale in the dynamics underlying the \Delta I = 1/2 rule can be…
Flavour changing neutral current (FCNC) transitions $c\to u\gamma$ and $c\to ul^+l^-$ are very rare in the standard model and present an interesting probe for the physics beyond it. We study long distance contamination to these short…
We present a detailed theoretical study of nonfactorizable contributions of the charm-quark loop to the amplitude of the $B_s\to \gamma\,\gamma$ decay. This contribution involves the $B$-meson three-particle Bethe-Salpeter amplitude,…
We investigate the radiative $B_{c} \to D_{s1} \gamma$ transition in the framework of QCD sum rules. In particular, we calculate the transition form factors responsible for this decay in both weak annihilation and electromagnetic penguin…
Exclusive B decays can be factorized as convolutions of hard scattering amplitudes involving the weak interaction with universal hadron distribution amplitudes, thus providing a new QCD-based phenomenology. In addition, semi-leptonic decay…
The flavor changing transitions in the c->u gamma, c->u gamma gamma and c->u l+ l- offer the possibility to search for new physics in the charm sector. We investigate dominant decay mechanisms in the radiative decays D->V gamma, D->P(V) l+…
The radiative leptonic $B\to \gamma\ell\nu_{\ell}$ decay serves as an ideal platform to determine the $B$-meson inverse moment which is a fundamental nonperturbative parameter for the $B$ meson. In this paper, we explore precise QCD…
The perturbative QCD corrections to the nonleptonic decay rate of the $b$ quark are discussed. By considering the limit where the final charmed quarks are slow, it is argued that the coefficients of the $\alpha_s^2$ terms, corresponding to…
We compute for the first time the long-distance penguin contribution to the double radiative $B$-meson decays due to the purely hadronic operators acting with the electromagnetic current in the background soft-gluon field from first…
We have calculated the decay amplitude for the process $K_{S}$ $\to$ $\gamma \gamma$ at one loop order in chiral perturbation theory. As a new improvement we have included the weak mass term which is only relevant for processes with…
We perform a comprehensive study of a number of rare charm decays, incorporating the first evaluation of the QCD corrections to the short distance contributions, as well as examining the long range effects. For processes mediated by the…
The heavy quark expansion implemented through an operator product expansion provides us with a treatment of inclusive decays of beauty and charm hadrons that is genuinely derived from QCD,though it requires one additional assumption, namely…
The calculation of QCD corrections beyond the leading logarithmic approximation for the short-distance dominated rare decay $K^+\to\pi^+\nu\bar\nu$ is summarized. This analysis requires the complete ${\cal O}(\alpha_s)$ corrections to the…
We study the spectra of the bottomonium and B_c states within perturbative QCD up to order alpha_s^4. The O(Lambda_QCD) renormalon cancellation between the static potential and the pole mass is performed in the epsilon-expansion scheme. We…
We revisit the rare decays of the Higgs boson to two different quarks in the Standard Model, which arise at the one-loop level. We perform Taylor series expansions to the complete form factors of the decay amplitudes, according to their…
Weak radiative hyperon decays are considered in the framework of a quark model. The phenomenological model includes 1-quark transitions with the effective $sd\gamma$-vertex and 2-quark ones with the W-exchange $s+u\to u+d+\gamma$ and turns…
Using data recorded at centre-of-mass energies around 183 GeV and 189 GeV with the OPAL detector at LEP, the fundamental coupling of the charm quark to the W boson has been studied. The ratio Rc^W = Gamma(W -> cX)/Gamma(W -> hadrons) has…