ρ-meson longitudinal leading-twist distribution amplitude within QCD background field theory

Abstract

We revisit the ρ-meson longitudinal leading-twist distribution amplitude (DA) φ 2;ρ by using the QCD sum rules approach within the background field theory. To improve the accuracy of the sum rules for its moments ξ n;ρ , we include the next-to-leading order QCD correction to the perturbative part and keep all non-perturbative condensates up to dimension-six consistently within the background field theory. The first two moments read ξ 2;ρ |1GeV = 0.241(28) and ξ 4;ρ |1GeV = 0.109(10), indicating a double humped behavior for φ 2;ρ at small energy scale. As an application, we apply them to the B → ρ transition form factors within the QCD light-cone sum rules, which are key components for the decay width Γ(B → ρℓν ℓ ). To compare with the world-average of Γ(B → ρℓν ℓ ) issued by Particle Data Group, we predict |V ub | = 3.19 +0.65 −0.62 , which agrees with the BABAR and Omnès parameterization prediction within errors.

Light-cone distribution amplitudes of vector meson in a large momentum effective theory

“…The LCDAs for vector mesons, e.g., the ρ meson, are more complex since the vector meson can be either longitudinally or transversely polarized. The LCDAs of vector mesons have been studied in various approaches, e.g, the QCD sum rules [5][6][7], the lattice QCD (LQCD) calculation, etc. However, at present the LCDAs of ρ meson are only calculated up to the second moment in LQCD approach [8,9].A novel strategy of evaluating light-cone correlators is the large momentum effective theory (LaMET), in which the full x (x is the longitudinal momentum fraction) dependence can be calculated [10,11].…”

Longitudinal leading-twist distribution amplitude of the J/ψ meson within the background field theory

“…to do the LCSR calculation on the TFFs, one can suppress the contributions from other LCDAs and highlight the contributions from the longitudinal leading-twist LCDA φ 2;J/ψ , thus showing the properties of φ 2;J/ψ via a more transparent way. Thus the LCSRs derived by using the left-handed chiral correlator [24,25] inversely provide good platforms for testing the behavior of φ 2;J/ψ .…”

“…The four B c → J/ψ TFFs V (q 2 ), A 0 (q 2 ), A 1 (q 2 ) and A 2 (q 2 ), as mentioned in the Introduction, can be read from Refs. [24,25], which are either directly or indirectly related to the twist-2 LCDA φ 2;J/ψ .…”

Generalized Parton Distributions from charged current meson production

“…where the coefficients a 2n µ 2 have mild multiplicative dependence on the factorization scale µ and are frequently used to characterize the shape of the distribution amplitude. At present it is expected that the coefficients a 2n should be small, with current estimates [14,15]…”