Related papers: Hard spectator interactions in B to pi pi at order…
The next-to-next-to-next-to-leading order (N^3LO) Hamiltonian of potential nonrelativistic QCD is derived. The complete matching of the Hamiltonian and the contribution from the ultrasoft dynamical gluons relevant for perturbative…
In this work, we give a detailed discussion for QCD factorization involved the complete chirally enhanced power corrections for B decays to two light pseudoscalar mesons, and present some detailed calculations of radiative corrections at…
In this paper we perform a systematic study for the three $B \to (\pi^+\pi^-,\pi^+\pi^0,\pi^0\pi^0)$ decays in the perturbative QCD (pQCD) factorization approach with the inclusion of all currently known next-to-leading order (NLO)…
We investigate the soft spectator scattering contribution for the FF $F_{1}$. We focus our attention on factorization of the hard-collinear scale $\sim Q\Lambda$ corresponding to transition from SCET-I to SCET-II. We compute the leading…
We present the results of our lattice QCD study of the $\pi\gamma\to\pi\pi$ process, where the $\rho$ resonance appears as an enhancement in the transition amplitude. We use $N_f=2+1$ clover fermions on a lattice of $L=3.6$ fm and a pion…
We investigate the $I=1$ $\pi \pi$ interaction using the HAL QCD method in lattice QCD. We employ the (2+1)-flavor gauge configurations on $32^3 \times 64$ lattice at the lattice spacing $a \approx 0.0907$ fm and $m_{\pi} \approx 411$ MeV,…
We evaluate in the next-to-leading approximation the forward impact factor for the virtual photon to light vector meson transition in the case of longitudinal polarization. We find that in the hard kinematic domain, both in the leading and…
We report on the perturbative $O(\alpha_s)$ correction to the light-cone QCD sum rule for the $B\to \pi$ transition form factor $f^+$. The correction to the product $f_Bf^+$ in leading twist approximation is found to be about 30%, that is…
In this paper, we investigate the vertex corrections and spectator hard scattering contributions to $B \to \chi_{c0,2}K$ decays, which has no leading contribution from naive factorization scheme. A non-zero binding energy $b=2m_c-M$ is…
The present calculations in perturbative QCD reach the order $\alpha_s^4$ for several correlators calculated to five loops, and the huge computational difficulties make unlikely the full six-loop calculation in the near future. This…
A recent lattice QCD study has shown that the $N-J/\psi$ potential is attractive at all distances, and its long-range tail is well described by two-pion exchange. Here, we study to what extent the long-range part of the attraction can be…
Lattice QCD studies of hadron-hadron interactions are performed by computing the energy levels of the system in a finite box. The shifts in energy levels proportional to inverse powers of the volume are related to scattering parameters in a…
We reanalyze deep inelastic scattering data of BCDMS Collaboration by including proper cuts of ranges with large systematic errors. We perform also the fits of high statistic deep inelastic scattering data of BCDMS, SLAC, NM and BFP…
Various exclusive and inclusive decays of B mesons are studied, at present, with dedicated experiments at ``B factories''. In order to compete with the experimental accuracy, we need a reliable theoretical framework to compute strong…
Exclusive non-leptonic two-body decays of $B$ mesons have been studied extensively in the past two decades within the framework of factorization. However, the exploration of the corresponding three-body case has only started recently, in…
We analyze the analytic structure of the Covariant Spectator Theory (CST) contribution to the self-energy amplitude for a scalar particle in a \phi^2 \chi-theory. To this end we derive dispersion relations in 1+1 and in 3+1 dimensional…
We computed the static potential and Wilson loops to $O(\alpha^2)$ in perturbation theory for different lattice quark and gluon actions. In general, we find short distance lattice data to be well described by ``boosted perturbation…
I describe how to calculate cross sections for hard-scattering processes in high energy collisions at next to leading order in QCD. I consider infrared-safe quantities and I assume that the scattering amplitudes are known in analytic form…
We perform a perturbative QCD analysis of the nucleon's Pauli form factor $F_2(Q^2)$ in the asymptotically large $Q^2$ limit. We find that the leading contribution to $F_2(Q^2)$ has a $1/Q^6$ power behavior, consistent with the well-known…
The calculations for the production of heavy quarks in deeply inelastic scattering (DIS) can be seen as an illustrative example in the framework of perturbative Quantum Chromo Dynamics (pQCD). In this thesis, I give an overview of all steps…