Computing noncommutative Chern-Simons theory radiative corrections on the back of an envelope

We show that the renormalized U(N) noncommutative Chern-Simons theory can be defined in perturbation theory so that there are no loop corrections to the 1PI functional of the theory in an arbitrary homogeneous axial (time-like, light-like or space-like) gauge. We define the free propagators of the fields of the theory by using the Leibbrandt-Mandelstam prescription --which allows Wick rotation and is consistent with power-counting-- and regularize its Green functions with the help of a family of regulators which explicitly preserve the infinitesimal vector Grassmann symmetry of the theory. We also show that in perturbation theory the nonvanishing Green functions of the elementary fields of the theory are products of the free propagators.Comment: In memory of Professor G. Leibbrand

Quantum Field Kinetics of QCD: Quark-Gluon Transport Theory for Lightcone Dominated Processes

A quantum kinetic formalism is developed to study the dynamical interplay of quantum and statistical-kinetic properties of non-equilibrium multi-parton systems produced in high-energy QCD processes. The approach provides the means to follow the quantum dynamics in both space-time and energy-momentum, starting from an arbitrary initial configuration of high-momentum quarks and gluons. Using a generalized functional integral representation and adopting the `closed-time-path' Green function techniques, a self-consistent set of equations of motions is obtained: a Ginzburg-Landau equation for a possible color background field, and Dyson-Schwinger equations for the 2-point functions of the gluon and quark fields. By exploiting the `two-scale nature' of light-cone dominated QCD processes, i.e. the separation between the quantum scale that specifies the range of short-distance quantum fluctuations, and the kinetic scale that characterizes the range of statistical binary inter- actions, the quantum-field equations of motion are converted into a correspon- ding set of `renormalization equations' and `transport equations'. The former describe renormalization and dissipation effects through the evolution of the spectral density of individual, dressed partons, whereas the latter determine the statistical occurrence of scattering processes among these dressed partons. The renormalization equations and the transport equations are coupled, and hence must be solved self-consistently. This amounts to evolving the multi-parton system, from a specified initial configuration, in time and full 7-dimensional phase-space. This description provides a proba- bilistic interpretation and is therefore of important practical value for the solution of the dynamical equations of motion, e.g. by Monte Carlo simulation.Comment: 70 pages, latex, 12 figures as uu-encoded postscript fil

Gender and 5-years course of psychosis patients: focus on clinical and social variables

Most studies on gender and psychosis have focused on gender differences at illness onset or on the long-term outcome, whereas little is known about the impact of gender on the first years after psychosis onset. A total of 185 first episode psychosis (FEP) patients were followed for 5 years after psychosis onset, and gender differences were explored in psychopathology (PANSS), needs for care (CAN), and insight (SAI-E). Male patients showed more negative symptoms than females over time, whereas female patients showed higher levels of depressive symptoms than males throughout the study period. In addition, female patients presented more functioning unmet needs for care, but higher levels of insight into illness than males. Therapy and rehabilitative programs for FEP patients should be gender-targeted, as gender has proved to impact on psychopathology, needs for care, and insight in the very first years following psychosis onset

Evolution of e p fragmentation and multiplicity distributions in the Breit frame

Low x deep-inelastic ep scattering data, taken in 1994 at the H1 detector at HERA, are analysed in the Breit frame of reference. The evolution of the peak and width of the current hemisphere fragmentation function is presented as a function of Q and compared with e+e- results at equivalent centre of mass energies. Differences between the average charged multiplicity and the multiplicity of e+e- annihilations at low energies are analysed. Invariant energy spectra are compared with MLLA predictions. Distributions of multiplicity are presented as functions of Bjorken-x and Q^2, and KNO scaling is discussed.Comment: 24 pages, 9 Figures, figure 2 correcte