Factorization at fixed Q^2(1-x)
Abstract
We consider QCD factorization between hard and soft subprocesses in inclusive reactions where the momentum fraction x of one parton approaches unity as the hard scale Q^2 -> \infty, such that Q^2(1-x) is fixed. In this "BB limit" the entire (multi-parton) Fock state containing the high x parton is coherent with the hard subprocess. The soft contribution is given by a forward multiparton matrix element. The BB limit corresponds to a fixed (large or small) missing mass and is thus closely connected to exclusive production. We analyze the Drell-Yan process h + N -> \gamma^* + X in detail, explaining why the virtual photon is longitudinally polarized for h = \pi and transversely polarized for h = p. The BB limit may be relevant also for other phenomena observed at high x, such as the large single spin asymmetries of p p -> \Lambda^\uparrow X and in p p^\uparrow -> \pi X.
Cite
@article{arxiv.0808.0626,
title = {Factorization at fixed Q^2(1-x)},
author = {Paul Hoyer and Matti Jarvinen and Samu Kurki},
journal= {arXiv preprint arXiv:0808.0626},
year = {2009}
}
Comments
18 pages, 6 figures. v2: Version published in JHEP. Text modified as suggested by the referee