3,750 research outputs found
Ds+ -- Ds- Asymmetry in Photoproduction
Considering of the possible difference in strange and antistrange quark
distributions inside nucleon, we investigate the Ds+ -- Ds- asymmetry in
photoproduction in the framework of heavy-quark recombination mechanism. We
adopt two distribution models of strange sea, those are the light-cone
meson-baryon fluctuation model and the effective chiral quark model. Our
results show that the asymmetry induced by the strange quark distributions is
distinct, which is measurable in experiments. And, there are evident
differences between the predictions of our calculation and previous estimation.
Therefore, the experimental measurements on the Ds+ -- Ds- asymmetry may impose
a unique restriction on the strange-antistrange distribution asymmetry models.Comment: 11 page, 5 figure
Asymmetry in Photoproduction
By adopting two models of strange and antistrange quark distributions inside
nucleon, the light-cone meson-baryon fluctuation model and the effective chiral
quark model, we calculate the asymmetry in photoproduction in
the framework of heavy-quark recombination mechanism. We find that the effect
of asymmetry of strange sea to the asymmetry is considerable and
depending on the different models. Therefore, we expect that with the further
study in electroproduction, e.g. at HERA and CEBAF, the experimental
measurements on the asymmetry may impose a strong restriction
on the strange-antistrange distribution asymmetry models.Comment: 4 pages, talk presented by I. Caprini at the International Conference
on QCD and Hadronic Physics, June 16-20 2005, Beijin
Exclusive Decays to Charmonium and a Light Meson at Next-to-Leading Order Accuracy
In this paper the next-to-leading order (NLO) corrections to meson
exclusive decays to S-wave charmonia and light pseudoscalar or vector mesons,
i.e. , , , and , are performed within non-relativistic (NR)
QCD approach. The non-factorizable contribution is included, which is absent in
traditional naive factorization (NF). And the theoretical uncertainties for
their branching ratios are reduced compared with that of direct tree level
calculation. Numerical results show that NLO QCD corrections markedly enhance
the branching ratio with a K factor of 1.75 for and 1.31 for . In order to
investigate the asymptotic behavior, the analytic form is obtained in the heavy
quark limit, i.e. . We note that annihilation topologies
contribute trivia in this limit, and the corrections at leading order in expansion come from form factors and hard spectator interactions. At
last, some related phenomenologies are also discussed.Comment: 20 pages, 7 figures and 5 table
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