Factorization in exclusive quarkonium production

초록

We present factorization theorems for two exclusive heavy-quarkonium production processes: production of two quarkonia in e(+)e(-) annihilation and production of a quarkonium and a light meson in B-meson decays. We describe the general proofs of factorization and supplement them with explicit one-loop analyses, which illustrate some of the features of the soft-gluon cancellations. We find that violations of factorization are generally suppressed relative to the factorized contributions by a factor nu(2)m(c)/Q for each S-wave charmonium and a factor m(c)/Q for each L-wave charmonium with L > 0. Here, nu is the velocity of the heavy quark or antiquark in the quarkonium rest frame, Q = root s for e(+)e(-) annihilation, Q = m(B) for B-meson decays, root s is the e(+)e(-) center-of-momentum energy, m(c) is the charm-quark mass, and m(B) is the B-meson mass. There are modifications to the suppression factors if quantum-number restrictions apply for the specific process.

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