High-p⊥p_\perp Jets in Diffractive Electroproduction

The diffractive production of high-$p_{\perp}$ jets in deep-inelastic scattering is studied in the semiclassical approach. The $p_{\perp}$-spectra of $q {\bar q}$ and $q {\bar q} g$ diffractive final states are found to be qualitatively different. For $q {\bar q}$ final states, which are produced by `hard' colour-singlet exchange, the $p_{\perp}$-spectrum is much softer than for $q {\bar q} g$ final states, where the colour neutralization is `soft'. Furthermore, the two different final states can be clearly distinguished by their diffractive mass distributions.Comment: 9 pages, latex, 5 figure

Combined analysis of diffractive and inclusive structure functions in the semiclassical framework

Small-x DIS is described as the scattering of a partonic fluctuation of the photon off a superposition of target color fields. Diffraction occurs if the emerging partonic state is in a color singlet. Introducing a specific model for the averaging over all relevant color field configurations, both diffractive and inclusive parton distributions at some low scale Q_0^2 can be calculated. A conventional DGLAP analysis results in a good description of diffractive and inclusive structure functions at higher values of Q^2.Comment: 3 pages LaTeX, 3 figures, talk presented at the 7th International Workshop on Deep Inelastic Scattering and QCD (DIS99), Zeuthen, Germany, April 19-23, 199

Leptogenesis for Pedestrians

During the process of thermal leptogenesis temperature decreases by about one order of magnitude while the baryon asymmetry is generated. We present an analytical description of this process so that the dependence on the neutrino mass parameters becomes transparent. In the case of maximal CP asymmetry all decay and scattering rates in the plasma are determined by the mass M_1 of the decaying heavy Majorana neutrino, the effective light neutrino mass tilde{m}_1 and the absolute mass scale bar{m} of the light neutrinos. In the mass range suggested by neutrino oscillations, m_{sol} \simeq 8*10^{-3} eV \lesssim \tilde{m}_1 \lesssim m_{atm} \simeq 5*10^{-2} eV, leptogenesis is dominated just by decays and inverse decays. The effect of all other scattering processes lies within the theoretical uncertainty of present calculations. The final baryon asymmetry is dominantly produced at a temperature T_B which can be about one order of magnitude below the heavy neutrino mass M_1. We also derive an analytical expression for the upper bound on the light neutrino masses implied by successful leptogenesis.Comment: 55 pages, 14 figures include

Towards the Theory of Diffractive DIS

The large rapidity gap events, observed at HERA, have changed considerably our physical picture of deep inelastic scattering during the past years. We review the present theoretical understanding of diffractive DIS with emphasis on the close relation to inclusive DIS. This includes success and limitations of the leading twist description, the connection between diffractive and inclusive parton distributions in the semiclassical approach, the colour structure of the proton and comparison with data. The progress report concludes with a list of open questions.Comment: 19 pages, 8 figures; presented at `New Trends in HERA Physics', Ringberg Workshop, June 199

Quantum mechanics of baryogenesis

The cosmological baryon asymmetry can be explained as remnant of heavy Majorana neutrino decays in the early universe. We study this out-of-equilibrium process by means of Kadanoff-Baym equations which are solved in a perturbative expansion. To leading order the problem is reduced to solving a set of Boltzmann equations for distribution functions.Comment: 12 pages, 2 figures, typos corrected. To be published in Physics Letter