Search

χcJ (J=0, 1, 2) production associated with a charm quark pair in hadron collisions is calculated in the framework of nonrelativistic QCD at the Tevatron and LHC. It is found that the color-singlet contribution is small and the color-octet contribution may be dominant in the large pT region. The differential cross section of pp¯ →χc+cc¯ is at least 1 order of magnitude smaller than the next-to-leading order result of χcJ inclusive production pp¯ → χc+X; therefore χcJ production in pp¯ → χc+cc¯ may have negligible influence on the ratio Rχc=σχc2/σχc1 measured by CDF Collaboration at the Tevatron. The feed-down contribution from χcJ+c+c¯ to J/Ψ+c+c¯ is found to be large compared with J/Ψ direct production and may have important influence on the measurement of J/Ψ+c+c¯. The validity of fragmentation approximation for the process is also discussed. [ABSTRACT FROM AUTHOR]

We study O(αsv2) corrections to decays of 1S0 heavy quarkonium into light hadrons and two photons within the framework of nonrelativistic QCD and find these O(αsv2) corrections to have significant contributions especially for the decay into light hadrons. With these new results, experimental measurements of the hadronic width and the γγ width of ηc can be described more consistently. By fitting experimental data, we find the long-distance matrix elements of ηc to be ∣Rηc(0)∣2=0.834-0.197+0.281??GeV3 and «v2»ηc=0.232-0.098+0.121. Moreover, ηc(2S) is also discussed and the γγ decay width is predicted to be 3.34-2.10+2.06??KeV. [ABSTRACT FROM AUTHOR]

We extract the pion valence quark distribution qπv(x) from lattice QCD (LQCD) calculated matrix elements of spacelike correlations of one vector and one axial vector current analyzed in terms of QCD collinear factorization, using a new short-distance matching coefficient calculated to one-loop accuracy. We derive the Ioffe time distribution of the two-current correlations in the physical limit by investigating the finite lattice spacing, volume, quark mass, and higher-twist dependencies in a simultaneous fit of matrix elements computed on four gauge ensembles. We find remarkable consistency between our extracted qvπ(x) and that obtained from experimental data across the entire x range. Further, we demonstrate that the one-loop matching coefficient relating the LQCD matrix computed in position space to the qvπ(x) in momentum space has well-controlled behavior with Ioffe time. This justifies that LQCD-calculated current-current correlations are good observables for extracting partonic structures by using QCD factorization, which complements to the global effort to extract partonic structure from experimental data. [ABSTRACT FROM AUTHOR]