1,876 research outputs found
Ultrasoft contribution to heavy-quark pair production near threshold
We compute the third-order correction to the heavy-quark current correlation
function due to the emission and absorption of an ultrasoft gluon. Our result
supplies a missing contribution to top-quark pair production near threshold and
the determination of the bottom quark mass from QCD sum rules.Comment: 10 pages, LaTe
Quarkonium polarization as a test of non-relativistic effective theory
I compare current approaches to quarkonium production with regard to what
they tell us about quarkonium polarization. Predictions for
polarization in hadron-hadron and photon-hadron collisions are summarized.Comment: 6 pages, LaTeX, 3 figures included via epsf.sty, uses sprocl.sty
(provided
Spectator scattering at NLO in non-leptonic B decays: Tree amplitudes
We compute the 1-loop (alpha_s^2) correction to hard spectator scattering in
non-leptonic B decay tree amplitudes. This forms part of the NNLO contribution
to the QCD factorization formula for hadronic B decays, and introduces a new
rescattering phase that corrects the leading-order result for direct CP
asymmetries. Among the technical issues, we discuss the cancellation of
infrared divergences, and the treatment of evanescent four-quark operators. The
infrared finiteness of our result establishes factorization of spectator
scattering at the 1-loop order. Depending on the values of hadronic input
parameters, the new 1-loop correction may have a significant impact on
tree-dominated decays such as B -> pi pi.Comment: 28 pages, 5 figures, LaTe
Signatures of Color-Octet Quarkonium Production
I briefly review the nonrelativistic QCD picture of quarkonium production and
its confrontation with experiment in various production processes.Comment: 17 pages, LaTeX, 1 figure, sprocl.sty provided (To appear in the
Proceedings of the Second Workshop on Continuous Advances in QCD,
Minneapolis, U.S.A., March 1996
CP Violation
Several pieces of direct and indirect evidence now suggest that the
Kobayashi-Maskawa mechanism plays a distinguished role for CP violation at the
electroweak scale. This talk provides a general overview of CP violation in its
various contexts, emphasizing CP violation in flavour-violating interactions,
such as due to the Kobayashi-Maskawa mechanism. I then review a few recent
theoretical developments relevant to the interpretation of CP violation.Comment: 27 pages, LaTeX; plenary talk presented at the International
Europhysics Conference on High Energy Physics, Budapest, July 2001;
manuscript has some overlap with hep-lat/020101
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