TY - JOUR
T1 - KT factorization is violated in production of high-transverse-momentum particles in hadron-hadron collisions
AU - Collins, John
AU - Qiu, Jian Wei
PY - 2007/6/28
Y1 - 2007/6/28
N2 - We show that hard-scattering factorization is violated in the production of high-pT hadrons in hadron-hadron collisions, in the case that the hadrons are back-to-back, so that kT factorization is to be used. The explicit counterexample that we construct is for the single-spin asymmetry with one beam transversely polarized. The Sivers function needed here has particular sensitivity to the Wilson lines in the parton densities. We use a greatly simplified model theory to make the breakdown of factorization easy to check explicitly. But the counterexample implies that standard arguments for factorization fail not just for the single-spin asymmetry but for the unpolarized cross section for back-to-back hadron production in QCD in hadron-hadron collisions. This is unlike corresponding cases in e+e- annihilation, Drell-Yan, and deeply inelastic scattering. Moreover, the result endangers factorization for more general hadroproduction processes.
AB - We show that hard-scattering factorization is violated in the production of high-pT hadrons in hadron-hadron collisions, in the case that the hadrons are back-to-back, so that kT factorization is to be used. The explicit counterexample that we construct is for the single-spin asymmetry with one beam transversely polarized. The Sivers function needed here has particular sensitivity to the Wilson lines in the parton densities. We use a greatly simplified model theory to make the breakdown of factorization easy to check explicitly. But the counterexample implies that standard arguments for factorization fail not just for the single-spin asymmetry but for the unpolarized cross section for back-to-back hadron production in QCD in hadron-hadron collisions. This is unlike corresponding cases in e+e- annihilation, Drell-Yan, and deeply inelastic scattering. Moreover, the result endangers factorization for more general hadroproduction processes.
UR - http://www.scopus.com/inward/record.url?scp=34347401005&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34347401005&partnerID=8YFLogxK
U2 - 10.1103/PhysRevD.75.114014
DO - 10.1103/PhysRevD.75.114014
M3 - Article
AN - SCOPUS:34347401005
SN - 1550-7998
VL - 75
JO - Physical Review D - Particles, Fields, Gravitation and Cosmology
JF - Physical Review D - Particles, Fields, Gravitation and Cosmology
IS - 11
M1 - 114014
ER -