Related papers: Tree-level contribution to \bar{B} -> X_d gamma us…
We argue that the process $pp \to (\text{jet} \gamma)X$, for which a photon is observed inside a fully reconstructed jet and is treated as part of the jet, offers new probes of the so far little known fragmentation functions for photons. We…
I study bottom quark fragmentation in the Standard Model Higgs decay H->b bbar, within the framework of perturbative fragmentation functions. I resum large collinear logarithms ln(m_H^2/m_b^2) in the next-to-leading logarithmic (NLL)…
We present a preliminary determination of the inclusive branching fraction for the rare radiative penguin transition B -> X_{s} gamma. The measurement is based on a data sample of 60 million BB pairs collected between 1999 and 2001 with the…
We present a QCD-based approach to the endpoint region of the lepton spectrum in $\bar B\to X_u\,\ell\,\bar\nu$ decays. We introduce a genuinely nonperturbative form factor, the shape function, which describes the fall-off of the spectrum…
A simple quark-diquark model for nucleon and $\Lambda$ structure is used to calculate leading twist light-cone fragmentation functions for a quark to inclusively decay into P or $\Lambda$. The parameters of the model are determined by…
We compute the perturbative component of the fragmentation function of the $b$ quark to the best of the present theoretical knowledge. The fixed-order calculation to order $\alpha_s^2$ of the fragmentation function at the initial scale is…
Inclusive radiative decays $B_c\to\gamma u\bar{d}$ are considered. It is shown that photon emission allows one to bypass the chiral suppression and leads the increase of the branching fraction by about four orders of magnitude. The…
In this work, we study the radiative leptonic decays of $B^-$ and $D^-$ mesons using factorization approach. Factorization is proved to be valid explicitly at 1-loop level at any order of $O(\Lambda_{\rm QCD}\left/m_Q\right.)$. We consider…
The moments of the photon spectrum in the inclusive $B\to X_s\,\gamma$ decay can be calculated to order $\alpha_s$ accuracy at present, without knowing the $\alpha_s$ corrections to the effective Hamiltonian. We discuss the standard model…
Using methods of effective field theory, a systematic analysis of the fragmentation functions D_{a/H}(x,m_Q) of a hadron H containing a heavy quark Q is performed (with a=Q,Q_bar,q,q_bar,g). By integrating out pair production of virtual and…
Measuring the photon energy spectrum in radiative B decays provides essential help for gaining theoretical control over semileptonic B transitions. The hadronic recoil mass distribution in B -> X_u \ell\nu promises the best environment for…
We analyze the double radiative B-meson decays B_s -> gamma gamma and B_d -> gamma gamma in QCD factorization based on the heavy-quark limit m_b >> Lambda_QCD. We systematically discuss the various contributions to these exclusive…
We derive the QCD$\times$QED factorization theorem governing the leptonic decay $B^-\to\mu^-\bar\nu_\mu(\gamma)$ at all orders in $\alpha_s$ and $\alpha$. Electromagnetic corrections to this decay probe multiple scales, which we disentangle…
We review the theoretical understanding of the branching ratio and photon-energy spectrum in B -> Xs gamma decays at next-to-leading order in QCD, including consistently the effects of Fermi motion. For the Standard Model, we obtain B(B ->…
We present a measurement of the branching fraction and photon energy spectrum for the decay B --> X_s gamma using data from the BaBar experiment. The data sample corresponds to an integrated luminosity of 210 fb^{-1}, from which…
We review the main aspects of the fragmentation of bottom quarks in top quark decay. The NLO b-quark energy spectrum presents large mass logarithms ln(m_t^2/m_b^2), which can be resummed by the use of the approach of perturbative…
Fragmentation functions for charged particles in Z -> qq(bar) events have been measured for bottom (b), charm (c) and light (uds) quarks as well as for all flavours together. The results are based on data recorded between 1990 and 1995…
An analytic result for the O(alpha_s corrections to the triple differential B -> X_u l nu decay rate is presented, to leading order in the heavy-quark expansion. This is relevant for computing partially integrated decay distributions with…
We study the inclusive $H_b \to X_s \gamma$ decay with $H_b$ a beauty baryon, in particular $\Lambda_b$, employing an expansion in the heavy quark mass at $\mathit{O}(m_b^{-3})$ at leading order in $\alpha_s$, keeping the dependence on the…
Employing the QCD factorization formalism we compute $B_{u}^{-} \to \gamma^{\ast} \, \ell \, \bar \nu_{\ell}$ form factors with an off-shell photon state possessing the virtuality of order $m_b \, \Lambda_{\rm QCD}$ and $m_b^2$,…