Kinematical Constraints on QCD Factorization in the Drell-Yan Process
We study factorization schemes for parton shower models in hadron-hadron collisions. As an example, we calculate lepton pair production mediated by a virtual photon in quark--anti-quark annihilation, and we compare factorized cross sections obtained in the conventional $\bar{\rm MS}$ scheme with those obtained in a factorization scheme in which a kinematical constraint due to parton radiation is taken into account. We discuss some properties of factorized cross sections.
This paper discusses the dynamical properties of p-spin models with Kac interactions. For large but finite interaction range R one finds two different well separated time scales for relaxation. A first short time scale, roughly independent of R, on which the system remains confined to limited regions of the configuration space and an R dependent long time scale on which the system is able to escape from the confining regions. I will argue that the R independent time scales can be described through dynamical mean field theory, while non-perturbative new techniques have to be used to deal with the R dependent scales.