A. I. Onishchenko

Three-loop universal anomalous dimension of the Wilson operators in N = 4 SUSY Yang-Mills model

Abstract We present results for the three-loop universal anomalous dimension γuni(j) of Wilson twist-2 operators in the N =4 Supersymmetric Yang–Mills model. These expressions are obtained by extracting the most complicated contributions from the three loop non-singlet anomalous dimensions in QCD which were calculated recently. Their singularities at j=1 coincide with the predictions obtained from the BFKL equation for N =4 SYM in the next-to-leading order. The asymptotics of γuni(j) at large j is in an agreement with the expectations based on an interpolation between week and strong coupling regimes in the framework of the AdS/CFT correspondence.

Semileptonic Bc-meson decays in sum rules of QCD and NRQCD

The semileptonic B_c-meson decays into the heavy quarkonia J/\psi (\eta_c) and a pair of leptons are investigated in the framework of three-point sum rules of QCD and NRQCD. Calculations of analytical expressions for the spectral densities of QCD and NRQCD correlators with account for the Coulomb-like \alpha_s/v terms are presented. The generalized relations due to the spin symmetry of NRQCD for the form factors of B_c\to J/\psi (\eta_c)l\nu_l transitions with l denoting one of the leptons e, \mu or \tau, are derived at the recoil momentum close to zero. This allows one to express all NRQCD form factors through a single universal quantity, an analogue of Isgur-Wise function at the maximal invariant mass of lepton pair. The gluon condensate corrections to three-point functions are calculated both in full QCD in the Borel transform scheme and in NRQCD in the moment scheme. This enlarges the parameteric stability region of sum rule method, that makes the results of the approach to be more reliable. Numerical estimates of widths for the transitions of B_c\to J/\psi (\eta_c)l\nu_l are presented.Abstract The semileptonic Bc-meson decays into the heavy quarkonia J/ψ(ηc) and a pair of leptons are investigated in the framework of three-point sum rules of QCD and NRQCD. Calculations of analytical expressions for the spectral densities of QCD and NRQCD correlators with account for the Coulomb-like αs/v terms are presented. The generalized relations due to the spin symmetry of NRQCD for the form factors of Bc→J/ψ(ηc)lνl transitions with l denoting one of the leptons e,μ or τ, are derived at the recoil momentum close to zero. This allows one to express all NRQCD form factors through a single universal quantity, an analogue of Isgur–Wise function at the maximal invariant mass of lepton pair. The gluon condensate corrections to three-point functions are calculated both in full QCD in the Borel transform scheme and in NRQCD in the moment scheme. This enlarges the parameteric stability region of sum rule method that makes the results of the approach to be more reliable. Numerical estimates of widths for the transitions of Bc→J/ψ(ηc)lνl are presented.

Bosonic corrections to Delta r at the two loop level

The details of the recent calculation of the two-loop bosonic corrections to the muon lifetime in the Standard Model are presented. The matching on the Fermi theory is discussed. Renormalisation in the on-shell and in the MS scheme is studied and transition between the schemes is shown to lead to identical results. High precision numerical methods are compared with mass difference and large mass expansions.

Spectator effects and lifetimes of heavy hadrons

We present a calculation of subleading 1/m{sub b} corrections to spectator effects in the ratios of beauty hadron lifetimes in heavy-quark expansion. We find that these effects are sizable and should be taken into account in systematic analyses of heavy hadron lifetimes. In particular, the inclusion of 1/m{sub b} corrections brings into agreement the theoretical predictions and experimental observations of the ratio of lifetimes of {lambda}{sub b} baryon and B{sub d} meson. We obtain {tau}(B{sub u})/{tau}(B{sub d})=1.06{+-}0.02, {tau}(B{sub s})/{tau}(B{sub d})=1.00{+-}0.01, {tau}({lambda}{sub b})/{tau}(B{sub d})=0.86{+-}0.05.

Doubly charmed baryon production in hadronic experiments

In the leading order of perturbative QCD one calculates the total and differential cross-sections for the hadronic production of doubly charmed baryons

Two-loop sunset diagrams with three massive lines

\Xi_{cc}

Lambda(b) lifetime puzzle in heavy quark expansion

and

On soft theorems and form factors in \( \mathcal{N}=4 \) SYM theory

\Xi_{cc}^*

Pion form-factor and QCD sum rules: Case of axial current

in different experiments. The experimental evaluation of cross-sections for the

Heavy mass expansion, light by light scattering and the anomalous magnetic moment of the muon

J/\Psi +D + \bar D