Exclusive decays χcJ→K∗(892)K\chi_{cJ}\to K^*(892)K within the effective field theory framework

We study hadronic decays $\chi_{cJ}\rightarrow K^*(892)\bar{K}$ within the effective field theory framework. We consider the colour-singlet and colour-octet contributions and study their properties using (p)NRQCD effective theory. We show that infrared singularities in collinear integrals of the colour-singlet amplitudes can be absorbed into the renormalisation of the colour-octet matrix elements. The heavy quark spin symmetry allows us to establish a relation between the colour-octet matrix elements and to define the spin symmetry breaking corrections which are free from infrared singularities. We apply obtained results for a phenomenological description of the branching fractions.Comment: 25 pages, 7 figures, typos corrected, text improved, version accepted for publication in EPJ

A study of relativistic corrections to J/ψ→ppˉ J/\psi\rightarrow p\bar{p} decay

We study relativistic corrections in exclusive $S$-wave charmonium decays into proton-antiproton final state. We calculate the NRQCD corrections to the dominant decay amplitude, which depend on the nucleon twist-3 light-cone distribution amplitudes only. It is shown that in this case the collinear factorisation is also valid beyond the leading-order approximation. Our numerical estimates show that relativistic correction of relative order $v^2$ provides large numerical impact.Comment: 22 pages, 2 figure

Relativistic corrections to ψ(nS)→ρπ\psi(nS)\to\rho\pi exclusive decays and their role in the understanding of the ρπ\rho\pi-puzzle

We study relativistic corrections to exclusive $S$-wave charmonium decays into $\rho\pi$ and $\gamma\pi$ final states. The contribution of relative order $v^2$ and the set of associated higher order corrections are calculated using NRQCD and collinear factorisation framework. Numerical estimates show that the dominant effect is provided by the corrections of relative order $v^2$. The numerical values of these contributions are of the same order as the leading-order ones. These results suggest a scenario where the sum of relativistic and radiative QCD corrections could explain the $\rho\pi$-puzzle.Comment: 15 pages, 1 figure, few typos are corrected, the text is improved and the discussion $\gamma \pi$ is extended. Accepted for publication in Phys.Rev.

A study of power suppressed contributions in

The power suppressed amplitude which describes the Pauli ($$\sigma ^{\mu \nu }$$) coupling in the $$J/\psi \rightarrow p\bar{p}$$ decay is calculated within the effective field theory framework. It is shown that at the leading-order approximation this contribution is factorisable and the overlap with the hadronic final state can be described by collinear matrix elements. The obtained contribution depends on the nucleon light-cone distribution amplitudes of twist-3 and twist-4. This result is used for a qualitative phenomenological analysis of existing data for $$J/\psi \rightarrow p\bar{p}$$ decay: branching ratio and the angular distribution in the cross section $$e^+e^-\rightarrow J/\psi \rightarrow p\bar{p}$$. It is found that the power corrections provide a large numerical effect

Wide Angle Compton Scattering within the SCET factorization Framework

Existing data for the electromagnetic proton form factors and for the cross section of the wide angle Compton scattering (WACS) show that the hard two-gluon exchange mechanism (collinear factorization) is still not applicable in the kinematical region where Mandelstam variables s ~ −t ~ −u are about few GeV2. On the other hand these observables can be described in phenomenological models where spectator quarks are soft which assumes a large contribution due to the soft-overlap mechanism. It turns out that the simple QCD factorization picture is not complete and must also include the soft-overlap contribution which can be described as a certain matrix element in the soft collinear effective theory (SCET). Then the leading power contribution to WACS amplitude is described as a sum of the hard- and soft-spectator contributions. The existing experimental data allows one to check certain conclusions based on the assumption about dominant role of the soft-spectator mechanism

Erratum to: A study of power suppressed contributions in

Few typos and two mistakes has been found in the text of the published version of the paper. Unfortunately these errors provide a strong impact on the numerical results and therefore some of the discussed observations has been changed. The updated text includes the corrected formulas, updated numerical results and conclusions. It is found that the computed power suppressed contribution provides important numerical effect for the observable $$\alpha$$ but the absolute value of the power suppressed amplitude is considerably smaller than one obtained before. The obtained numerical estimates are more consistent with the effective field theory power counting and provide a better agreement with the existing data

CALCULATION OF 1/N-DECOMPOSITIONS OF CRITICAL INDICES IN GROSS-NEVE MODEL BY A CONFORMAL BOOTSTRAP METHOD

The critical conformal invariance of the Green function for the Gross-Neve model has been proved. The critical indices with accuracy 1/N*992 and 1/N*993 have been calculated in the free space dimensionality by a conformal bootstrap method. The anomal dimensionalities of the mass and field have been calculated with five-loop accuracyAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Wide Angle Compton Scattering within the SCET factorization Framework

Existing data for the electromagnetic proton form factors and for the cross section of the wide angle Compton scattering (WACS) show that the hard two-gluon exchange mechanism (collinear factorization) is still not applicable in the kinematical region where Mandelstam variables s ~ −t ~ −u are about few GeV2. On the other hand these observables can be described in phenomenological models where spectator quarks are soft which assumes a large contribution due to the soft-overlap mechanism. It turns out that the simple QCD factorization picture is not complete and must also include the soft-overlap contribution which can be described as a certain matrix element in the soft collinear effective theory (SCET). Then the leading power contribution to WACS amplitude is described as a sum of the hard- and soft-spectator contributions. The existing experimental data allows one to check certain conclusions based on the assumption about dominant role of the soft-spectator mechanism