The problem of the vacuum energy decay is studied for both signs of the cosmological constant, through the analysis of the vacuum survival amplitude, defined in terms of the conformal time, z, by Aðz; z0Þ hvac zjvac z0i. Transition amplitudes are computed for finite time span, Z z0 z, and their late time behavior (directly related to the putative decay width of the state), and the transients ar...

Variation of constants in the very early universe can generate inflation. We consider a scenario where the strong coupling constant was changing in time and where the gluon condensate underwent a phase transition ending the inflation.

Ordinary and Radiative Muon Capture Reactions are reviewed with regards to the evidence for a renormalization of the induced pseudoscalar coupling constant inside the nucleus. Emphasis is placed on the new results which have become available since the WEIN-92 conference.

A brief review on the status of unpolarized parton densities and the determination of the QCD scale ΛQCD from deep-inelastic scattering data is presented.

The mechanism of gaugino condensation has emerged as a prime candidate for supersymmetry breakdown in low energy effective supergravity (string) models. One of the open questions in this approach concerns the size of the gauge coupling constant which is dynamically fixed through the vev of the dilaton. We argue that a nontrivial gauge kinetic function f(S) could solve the potential problem of a...

Inverted hybrid inflation (in which the inflaton field slowly rolls away from the origin, giving a spectral index n ∼ < 1) is an appealing variant of the more usually studied hybrid model. Analysing the model alongside the ordinary hybrid case, we show that, in order to provide the correct density perturbations consistent with the COBE measurements, the dimensionless coupling constants of the i...

We argue that accounting for higher order corrections in QCD by integrating a running coupling constant through an infrared region can be most easily done with making use of a scheme without the Landau pole. Within this approach the entire ambiguity of the answer is identical to that of the choice of renormalization scheme. The uncertainties for the τ lepton width resulting from such a techniqu...

We analyze the allowed spectrum of electric and magnetic charges carried by dyons in (toroidally compactified) heterotic string theory in four dimensions at arbitrary values of the string coupling constant and θ angle. The spectrum is shown to be invariant under electric-magnetic duality transformation, thereby providing support to the conjecture that this is an exact symmetry in string theory.

A review is given of the latest results on jet production and studies of event shape variables in deep inelastic scattering at HERA. Jet cross sections studies for inclusive jet and dijet events are presented and compared to next-to-leading order QCD calculations. Extraction of the strong coupling constant αs is discussed.

We study matrix string scattering amplitudes and matrix string instantons on a marked Riemann surface in the limit of a vanishing string coupling constant. We give an explicit parameterization of the moduli space of such instantons. We also give a description of the set of fermionic supermoduli. The integration over the supermoduli leads to the inclusion of picture changing operators at the int...