相关论文: Mass Corrections to the Vector Current Correlator
We compute the one-loop QCD amplitudes for the decay of an off-shell vector boson with vector couplings into a quark-antiquark pair accompanied by two gluons keeping, for the first time, all orders in the number of colours. Together with…
We construct an improved version of nonrelativistic QCD for use in lattice simulations of heavy quark physics, with the goal of reducing systematic errors from all sources to below 10\%. We develop power counting rules to assess the…
We compute the QCD corrections at next-to-leading order for the process $gg \rightarrow ZH$, including both the virtual two-loop terms and real-emission contributions. The two-loop box diagrams in the virtual corrections are approximated…
In this paper, we study the next-to-next-to-leading-order (NNLO) QCD corrections for the process $e^+e^- \to J/\psi+J/\psi$ at the $B$ factories. By including the NNLO corrections, the cross section turns negative due to the poor…
Quenched and partially quenched chiral perturbation theory for vector mesons is developed and is used to extract chiral loop correction to the $\rho$ meson mass. Connections to fully quenched and totally unquenched chiral perturbation…
We investigate two exclusive processes, e+ e- -> eta_c + gamma and e+ e- -> J/psi + J/psi, at the center-of-momentum energy sqrt{s}=10.58 GeV within the framework of the nonrelativistic QCD factorization approach. A class of relativistic…
We calculate the next-to-leading order QCD corrections to $B$ to scalar meson form factors from QCD light-cone sum rules with $B$ meson light-cone distribution amplitudes. We demonstrate that the $B$ meson-to-vacuum correlation functions…
The two-loop QCD radiative corrections to the $B_c$ meson leptonic decay rate are calculated in the framework of NRQCD factorization formalism. Two types of master integrals appearing in the calculation are obtained analytically for the…
We compute three-loop corrections of $\mathcal{O}(\alpha_{s}^3)$ to form factors with one massive and one massless quark coupling to an external vector, axialvector, scalar, pseudoscalar, or tensor current. We obtain analytic results for…
The transverse momentum spectra of weak gauge bosons and their ratios probe the underlying dynamics and are crucial in testing our understanding of the Standard Model. They are an essential ingredient in precision measurements, such as the…
We calculate the QCD corrected effective Hamiltonian for $B\bbar$--Mixing in heavy quark effective theory including corrections of the order $\Lambda_{QCD} / m_b$. The matrix elements of the subleading operators are estimated using the…
We calculated the complete next-to-leading order(NLO) QCD corrections to the $t\bar t b \bar b$ production process at a $\gamma \gamma$ collider in the standard model(SM). The calculation of the one-loop QCD correction includes the…
This talk presents details of the calculation of two-loop corrections to heavy baryon currents containing one heavy quark in leading order of the $1/m_Q$-expansion, i.e. in the limit of Heavy Quark Symmetry (HQS). The calculations lead to…
We calculate the radiative corrections to the current-current correlator of the hybrid current $g\bar q(x)\gamma_{\nu}iG_{\mu\nu}^aT^aq(x)$. Based on this new result we use the QCD sum rule approach to estimate lower bounds on the masses of…
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…
Cross sections of the heavy quarkonium production process $e^+e^-\to H + \gamma$ at the c.m. energy of $Z^0$-boson resonance are calculated at leading order in $\alpha_s$ with relativistic corrections resummed within the framework of…
Perturbative QCD corrections to hadronic $\tau$ decays and $e^+e^-$ annihilation into hadrons below charm are obtained from the Adler function, which at present is known in the chiral limit to five-loop accuracy. Extractions of the strong…
We compute corrections to the gyromagnetic factor of an electron bound in a hydrogen-like ion at order alpha^2(Z alpha)^5. This result removes a major uncertainty in predictions for silicon and carbon ions, used to determine the atomic mass…
We compute the one-loop (hard) matching correction to heavy-to-light transition currents in soft-collinear effective theory (SCET) to sub-leading power in the SCET expansion parameter for an arbitrary Dirac structure of the QCD weak…
We discuss the one-loop radiative corrections to the reaction e^+ e^- -> X^+_a X^-_b, for a,b=1,2 where X^+_{1,2} are the charginos of the minimal supersymmetric standard model. We calculate the leading one loop radiative corrections…