Related papers: Analysis of the QCD-improved factorization in B ->…
We discuss applications of QCD sum rules on the light-cone to the form factors of the exclusive transitions $B \rightarrow \pi$ and $D\rightarrow \pi$, and to the $B^*B \pi$ and $D^*D \pi$ coupling constants. In the light of our results we…
We prove that in the limit $m_b, m_c\to\infty$ with $m_c/m_b$ fixed, factorization holds at order $\alpha_s$ for the decay $\Lambda_b^0\to\Lambda_c^+\pi^-$. This proof is done in the infinite-momentum frame in which the momenta of $\pi$,…
We prove $k_T$ factorization theorem in perturbative QCD (PQCD) for exclusive processes by considering $\pi\gamma^*\to \gamma(\pi)$ and $B\to\gamma(\pi) l\bar\nu$. The relevant form factors are expressed as the convolution of hard…
We study two-body exclusive decays of the form B -> D^(*) L (L = \pi, \rho) in the heavy quark limit. We perform a renormalon analysis of such processes to determine the order at which nonperturbative factorization-breaking power…
We report on the computation of the $B_s$ meson decay constant in Heavy Quark Effective Theory on the lattice. The next to leading order corrections in the HQET expansion are included non-perturbatively. We estimate higher order…
We use the new symmetries in the heavy quark limit to calculate the exclusive B-decays $B \rightarrow K \psi ({\psi}^{\prime})$ and $B \rightarrow K^* \psi ({\psi}^{\prime})$. The estimated decay rates are compared with experimental values.…
We point out that current estimates of form factors fail to explain the non-leptonic decays $B \to \psi K(K^{\ast})$ and that the combination of data on the semi-leptonic decays $D \to K(K^{\ast})\ell \nu$ and on the non-leptonic decays $B…
These lectures describe the most important theoretical methods in b-physics. We discuss the formalism of effective weak Hamiltonians, heavy quark effective theory, the heavy quark expansion for inclusive decays of b-hadrons and, finally,…
We carry out a comprehensive analysis of the full set of $\bar{B}_q \to D_q^{(*)}$ form factors for spectator quarks $q=u,d,s$ within the framework of the Heavy-Quark Expansion (HQE) to order $\mathcal{O}(\alpha_s, 1/m_b, 1/m_c^2)$. In…
I review important aspects of the perturbative QCD approach to exclusive $B$ meson decays, concentrating on factorization theorem, gauge invariance, end-point singularities, $k_T$ and threshold resummations, power counting, penguin…
We perform perturbative QCD factorization of infrared radiations associated with an energetic $b$ quark from a polarized top quark decay, taking the semi-leptonic channel as an example. The resultant formula is expressed as a convolution of…
In the present thesis I discuss the hard spectator interaction amplitude in $B\to\pi\pi$ at NLO i.e. at $\mathcal{O}(\alpha_s^2)$. This special part of the amplitude, whose LO starts at $\mathcal{O}(\alpha_s)$, is defined in the framework…
We have studied charmless two-body B decays involving $\eta$ and $\eta'$ in the framework of QCD improved factorization appraoch. The spectator hard scattering mechanism for $\eta'$ production have been re-examined and extended, which…
Applications of QCD factorization to $B\to\phi K$, charmless $B\to VV$, $B\to J/\psi K(K^*)$ and semi-inclusive decays $B\to MX$ are discussed.
The perturbative QCD (PQCD) approach based on $k_T$ factorization has made a great achievement for the QCD calculation of the hadronic B decays. Regulating the endpoint divergence by the transverse momentum of quarks in the propagators, one…
A method of deriving bounds on the weak meson form factors, based on perturbative QCD, analyticity and unitarity, is generalized in order to fully exploit heavy quark spin symmetry in the ground state $(L=0)$ doublet of pseudoscalar $(B)$…
We report on recent progress on perturbative QCD calculations of certain exclusive rare weak $B$ meson decays involving hard photons. In the limit of a photon energy $E_\gamma$ much larger than $\Lambda_{QCD}$, the amplitudes for such…
High-energy factorization in QCD is investigated beyond leading order and its relationship to the factorization theorem of mass singularities is established to any collinear accuracy. Flavour non-singlet observables are shown to be regular…
The energy range and quality of strong-interaction data from recent years demand the study of higher orders in perturbative QCD, and of nonperturbative effects. I discuss a selection of recent progress in the theory of QCD at high energy,…
It is shown that up to an over all scale the lowest-order QCD corrections to $t\to H^+b$ and to $t\to W^+b$ are the same in the heavy top limit. Asymptotically, they are given by $-{4\alpha_s\over 3\pi}[{\pi^2\over 3}-{5\over 4}]$,…