منابع مشابه
Υ decay into charmonium and the color octet mechanism
A factorization theorem for P -wave quarkonium production, recently derived by Bodwin, Braaten, Yuan and Lepage, is applied to Υ → χcJ +X, where χcJ labels the PJ charmonium states. The widths for χcJ production through color-singlet P -wave and color-octet S-wave cc̄ subprocesses are computed each to leading order in αs. Experimental data on Υ → J/ψ+X is used to obtain an upper bound on a nonpe...
متن کاملTwo–Spin Asymmetry for ψ Photoproduction with Color–Octet Mechanism
We studied the photoproduction of ψ in the forward regions in polarized γp collisions at relevant HERA energies. We found that this reaction is very effective to test the color–octet mechanism which is based on the NRQCD factorization formalism. Furthermore we found that the value of the NRQCD matrix elements can be severely constrained by measuring the two–spin asymmetry, though the process de...
متن کاملColor-octet quarkonia production.
Gluon fragmentation represents the dominant source of high energy prompt quarkonia at hadron colliders. Fragmentation approximations break down, however, when a quarkonium’s transverse momentum becomes comparable to its mass. In this paper, we identify a large class of color-octet diagrams that mediate quarkonia production at all energies and reduce to the dominant set of gluon fragmentation gr...
متن کاملColor-octet quarkonia production. II.
We calculate the lowest order hadronic cross sections for producing colored heavy quark-antiquark pairs in L = S = 0 and L = S = 1 configurations. Such QQ[S (8) 0 ] and QQ[P (8) J ] states hadronize into ψQ quarkonia at the same order in the NRQCD velocity expansion as previously considered QQ[S (8) 1 ] pairs. Their contributions to prompt Psi and Upsilon production at the Tevatron bring the sh...
متن کاملColor - Octet ψ ′ Production at Low p ⊥
We study contributions from color-octet quarkonium formation mechanisms to p ⊥-integrated ψ ′ production cross sections in pion-nucleon reactions. The observed polarization of the ψ ′ is not reproduced by the lowest-order leading-twist color-singlet and color-octet mechanisms. This suggests that there are important quarkonium production mechanisms beyond leading twist.
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ژورنال
عنوان ژورنال: Physical Review D
سال: 1996
ISSN: 0556-2821,1089-4918
DOI: 10.1103/physrevd.54.4312