Abstract
The Next-To-Leading-Order (NLO) QCD corrections to J/ψ production via S-wave color-octet states at the Tevatron and LHC are calculated. There are only slight changes to the transverse momentum pt distributions of J/ψ production and polarization. By fitting the pt distribution of J/ψ production measured at Tevatron with both color-singlet and color-octet included, we obtain the color-octet matrix elements at NLO. The resulting pt distribution of J/ψ polarization still does not coincide with the experimental data. Therefore, we have reached the conclusion that the large discrepancy of J/ψ polarization between theory and experimental data cannot be solved by just including NLO corrections within non-relativistic QCD framework and then one has to explore solution from different angles.
Highlights
Making every endeavor to achieve precision determinations of heavy-to-light transition form factors is of utmost importance to, on the one hand, test the CKM sector of the Standard Model, and on the other side to sharpen our knowledge towards diverse facets of the theory of strong interaction (QCD)
To demonstrate the stability of the LCSR predictions we show the dependencies of fB+π (q2) on the “internal” sum rule parameters M2 and s0 in Fig. 6 where the two plots on the top are obtained from NLL resummation improved sum rules (78) with fπ extracted from the experimental data as explained before; while the two-point QCD sum rules of fπ are substituted in the LCSR to produce the two plots on the bottom
For the first time, perturbative corrections to B → π form factors from the QCD LCSR with B-meson distribution amplitudes (DAs) proposed in [1,2] where the sum rules for heavy-to-light form factors were established at tree level including contributions from both two-particle and three-particle DAs
Summary
Making every endeavor to achieve precision determinations of heavy-to-light transition form factors is of utmost importance to, on the one hand, test the CKM sector of the Standard Model, and on the other side to sharpen our knowledge towards diverse facets of the theory of strong interaction (QCD). Computations of B → π form factors with TMD factorization approach have been pushed to O(αs) for twist-2 [24,25] and twist-3 [26] contributions of pion DAs. one needs to be aware of the fact that TMD factorization of hard exclusive processes becomes extraordinarily delicate due to complex infrared subtractions beyond the leading order in αs [27] and a complete understanding of TMD factorization for exclusive processes with large momentum transfer has not been achieved to date on the conceptual side. We generalize factorization proof of the correction function to the one-loop order in Section 3 by showing a complete cancellation of soft contributions to the one-loop QCD diagrams and infrared subtractions determined by convolutions of the one-loop partonic DAs of the B-meson and the tree-level hard-scattering kernel, at leading power in /mb. Spectral representations of the convolution integrals for constructing the LCSR with B-meson DAs and two-point QCD sum rules for the decay constants of the B-meson and the pion are collected in Appendices B and C
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