QCD factorization at twist-3: the two parton contributions

Chinese Journal of Physics Taipei, 2008

The 1/m b corrections from the three parton qqg Fock state of the final state light meson in B → P P decays are evaluated by means of a collinear expansion method. The impacts of these corrections on the CP averaged branching ratios of the B → πK decays are analyzed.

2024

We study the nonleptonic decays of B → PP in the modified perturbative QCD approach, where P stands for pseudoscalar mesons. Transverse momenta of partons and the Sudakov factor are included, which help to suppress the contributions of soft interactions. The wave function of the B meson obtained from the relativistic potential model is used, and then the contributions in the infrared region cannot be suppressed completely. So a soft cutoff scale and soft form factors are introduced. The contributions with the scale higher than the soft cutoff scale are calculated with perturbative QCD, while the contributions lower than the cutoff scale are replaced by the soft form factors. To explain experimental data, we find that contributions of color-octet operators for the quark-antiquarks in the mesons in the final state need to be considered. The contributions of the color-octet operators are parametrized by a few parameters with the help of SU(3) flavor symmetry and symmetry breaking. These parameters for color-octet contributions are universal for all the nonleptonic decay modes of the B meson, where the mesons in the final state belong to the same flavor SU(3) nonet. Both the branching ratios and CP violations are studied. We find that the theoretical calculation can well explain the experimental data of B factories.

Physical Review D, 2006

We study O(α 2 s β 0 ) perturbative corrections to matrix elements entering two-body exclusive decays of the form B → ππ, πK in the QCD factorization formalism, including chirally enhanced power corrections, and discuss the effect of these corrections on direct CP asymmetries, which receive their first contribution at O(α s ). We find that the O(α 2 s β 0 ) corrections are often as large as the O(α s ) corrections. We find large uncertainties due to renormalization scale dependence as well as poor knowledge of the non-perturbative parameters. We assess the effect of the perturbative corrections on the direct CP violation parameters of B 0 → π + π -.

AIP Conference Proceedings, 2001

By using the recent experimental measurements of B → ππ and B → Kπ branching ratios, we find that the amplitudes computed at the leading order of the Λ QCD /m b expansion disagree with the observed BRs, even taking into account the uncertainties of the input parameters. Beyond the leading order, Charming and GIM penguins allow to reconcile the theoretical predictions with the data. Because of these large effects, we conclude, however, that it is not possible, with the present theoretical and experimental accuracy, to determine the CP violation angle γ from these decays. We compare our results with those obtained with the parametrization of the chirally enhanced nonperturbative contributions by BBNS. We also predict large asymmetries for several of the particleantiparticle BRs, in particular BR(B + → K + π 0), BR(B d → K + π −) and BR(B d → π + π −).

Nuclear Physics B, 2002

The next-to-next-to-leading order (NNLO) corrections in massless perturbative QCD are derived for the parton distributions of the photon and the deep-inelastic structure functions F γ 1 and F γ 2. We present the full photonic coefficient functions at order αα s and calculate the first six even-integer moments of the corresponding O(αα 2 s) photon-quark and photon-gluon splitting functions together with the moments of the αα 2 s coefficient functions which enter only beyond NNLO. These results are employed to construct parametrizations of the splitting functions which prove to be sufficiently accurate at least for momentum fractions x > ∼ 0.05. We also present explicit expressions for the transformation from the MS to the DIS γ factorization scheme and write down the solution of the evolution equations. The numerical impact of the NNLO corrections is discussed in both schemes.

The European Physical Journal C, 2002

We study two-body charmless hadronic decays of B mesons to a pseudoscalar meson (P) and a tensor meson (T) in the frameworks of both flavor SU(3) symmetry and generalized factorization. Certain ways to test validity of the generalized factorization are proposed, based on the flavor SU(3) analysis. We present a set of relations between a flavor SU(3) amplitude and a corresponding amplitude in the generalized factorization which bridge both approaches in B → P T decays. The branching ratios and CP asymmetries are calculated using the full effective Hamiltonian including all the penguin operators and the form factors obtained in the non-relativistic quark model of Isgur, Scora, Grinstein and Wise. We identify the decay modes in which the branching ratios and CP asymmetries are expected to be relatively large.

Journal of Physics G: Nuclear and Particle Physics, 2018

Using collinear factorization, we have calculated twist-six corrections to ηγ and η ′ γ transition form factors in QCD. Only a subset of light-cone operators of twist-six which can be factorized as a product of two gauge invariant operators has been considered. Resulting power corrections start as 1/Q 4 but coefficients are smaller compared to their counterparts for twist-four operators. Matrix element of pseudoscalar quark densities for u-and d-quarks between vacuum and meson state, h q , has considerable influence on the result. Results obtained by superimposing our results on those obtained in literature for leading and sub-leading power corrections for lower twists have been plotted and compared with data.

Physics Letters B, 1997

2012

We present the estimate of the branching ratio for the rare decay ¯ B 0 → D ∗ γ. We use QCD factorization approach in order to compute the amplitude of the process. The calculation is carried out with the leading order accuracy. The appearing non-perturbative matrix elements have been estimated using the large−Nc limit and QCD sum rule approach. We obtained that B ( ¯ B 0 → D ∗ γ) ≃ 1.52 × 10 −7. Such value of the branching fraction is too small in order to be measured at present experiments. ∗ On leave of absence from St. Petersburg Nuclear Physics Institute, 188350, Gatchina, Russia 1 1

Physical Review D, 2008

Two-body charmed decays B ðsÞ ! D ðsÞ P, D Ã ðsÞ P, D ðsÞ V, and D Ã ðsÞ V, where P and V denote the light pseudoscalar meson and vector meson, respectively, are analyzed in the perturbative QCD (pQCD) approach. Using the experimental data of six B ! DP channels, we test the D meson wave function by 2 fit. We give the branching ratios of all the charmed B decay channels, most of which agree with experiments amazingly well. The predicted B s decays can be confronted with the future experimental data. By straightforward calculations, our pQCD approach gives the right relative strong phase of a 2 =a 1 that agrees with experiments. We also predict the percentage of transverse polarizations in B ðsÞ ! D Ã V decay channels.