相关论文: Two-loop current-current operator contribution to …
Strong penguin operators are singlets under the right-handed flavor symmetry group SU(3)_R. However, they do not remain singlets when the operator is embedded in (partially) quenched QCD, but instead they become linear combinations of two…
We review recent progress in next-to-next-to-leading order (NNLO) perturbative QCD calculations with special emphasis on results ready for phenomenological applications. Important examples are new results on structure functions and jet or…
We make a further study of $CP$ asymmetries in the pure penguin-induced decay modes $B^{-}_{u}\rightarrow K^{(*)0} + K^{(*)-}$ and $B^{-}_{u} \rightarrow \bar{K}^{(*)0} + (\pi^{-}, \rho^{-}, a^{-}_{1})$ by using the two-loop…
We study the next-to-next-to-leading order (NNLO) evolution of flavour non-singlet quark densities and structure functions in massless perturbative QCD. Present information on the corresponding three-loop splitting functions is used to…
A careful quark-diagram analysis shows that a number of two-body nonleptonic $B$ decays can occur through the so-called hairpin diagram, a QCD loop-induced graph different from penguin in final-state hadronization of valence quarks. Using…
Motivated by the large difference between the direct CP asymmetries $A_{CP}(B^-\to \pi^0 K^-)$ and $A_{CP}(\bar{B}^{0}\to \pi^{+} K^{-})$, we combine the up-to-date experimental information on $B\to\pi K$, $\pi K^{\ast}$ and $\rho K$ decays…
We present the two-loop helicity amplitudes contributing to the next-to-next-to-leading order QCD predictions for W-boson production in association with two photons at the Large Hadron Collider. We derived compact analytic expressions for…
We present an analytical calculation of the two-loop QCD corrections to the electromagnetic form factor of heavy quarks. The two-loop contributions to the form factor are reduced to linear combinations of master integrals, which are…
We compute the two-loop massless QCD corrections to the helicity amplitudes for the production of two massive vector bosons in quark-antiquark annihilation, allowing for an arbitrary virtuality of the vector bosons: $q \bar q' \to V_1V_2$.…
The Bc -> BP,BV decays are studied with the QCD factorization approach (where P and V denote pseudoscalar and vector mesons, respectively). Considering the contributions of both current-current and penguin operators, the amplitudes of…
We present the next-to-next-to-next-to-leading order (N^3LO) contributions to the non-singlet splitting functions for both parton distribution and fragmentation functions in perturbative QCD. The exact expressions are derived for the terms…
Based on the most recent data in charmless B decays including the very recently reported large direct CP violations, it is shown that the weak phase gamma can well be extracted without two-fold ambiguity even only from two decay modes…
We present the three-loop calculations of the nonrelativistic QCD (NRQCD) current renormalization constants and corresponding anomalous dimensions, and the matching coefficients for the spatial-temporal tensor and spatial-spatial…
We report on recent progress on five-loop calculations in perturbative QCD. We discuss the computation of the perturbative quark condensate, decoupling in QCD, and the precision determination of charm and bottom quark masses. For the…
We discuss the correlations of charming penguin contributions to $B\to\pi\pi$, $\pi K$ and KK using approximate flavor SU(3) symmetry. Strong constraints are found from the direct CP asymmetries especially in $\pi K$ modes. We make a global…
We compute the two-loop corrections to the coefficient of the b --> s gamma magnetic penguin present in the limits of heavy top and/or heavy higgs. This kind of corrections affects in a significant way the observables measured at LEP. On…
Heavy--light QCD currents are matched with HQET currents at two loops and leading order in $1/m$. A single formula applies to all current matchings. As a by--product, a master formula for the two--loop anomalous dimension of the QCD current…
Strengthening constraints on new physics from the B -> X_s gamma branching ratio requires improving accuracy in the measurements and the Standard Model predictions. To match the expected Belle-II accuracy, Next-to-Next-to-Leading Order…
In the framework of analytic approach to QCD the nonperturbative contributions in running coupling of strong interaction up to 4-loop order are obtained in an explicit form. For all $Q>\Lambda$ they are shown to be represented in the form…
Using the approach based on conformal symmetry we calculate the two-loop coefficient function for the axial-vector contributions to two-photon processes in the $\overline{\rm MS}$ scheme. This is the last missing element for the complete…