/ 92 09 05 6 v 2 7 O ct 1 99 2 Tree Amplitudes in Noncritical

X iv : h ep - t h / 92 05 02 0 v 1 8 M ay 1 99 2 Divergences of Discrete States Amplitudes and Effective Lagrangian in 2 D String Theory . I . Ya

Scattering amplitudes for discrete states in 2D string theory are considered. Pole divergences of tree-level amplitudes are extracted and residues are interpreted as renormalized amplitudes for discrete states. An effective Lagrangian generating renormalized amplitudes for open string is written and corresponding Ward identities are presented. A relation of this Lagrangian with homotopy Lie alg...

x / 99 10 05 8 v 1 2 7 O ct 1 99 9 Rare Φ Decays and Exotic Hadrons

/ 92 05 09 6 v 1 2 7 M ay 1 99 2 Thermal history of the string universe

Thermal history of the string universe based on the Brandenberger and Vafa’s scenario is examined. The analysis thereby provides a theoretical foundation of the string universe scenario. Especially the picture of the initial oscillating phase is shown to be natural from the thermodynamical point of view. A precise description is also given of the transition process from the stringy phase to the...

ar X iv : h ep - p h / 99 05 38 5 v 1 1 8 M ay 1 99 9 1 Steps towards NNLO QCD calculations : collinear factorization at O ( α 2 S ) ∗

The properties of QCD in the soft and collinear limits play an important role in doing higher order calculations. The singularities arising in these limits prevents a straightforward integration of matrix elements to obtain physical cross sections. However, as far as NLO calculations are concerned, the universality property of these singularities provided a method to solve these problems. The s...

/ 99 09 18 7 v 2 2 6 O ct 1 99 9 Constant field strengths on T

We analyse field strength configurations in U(N) Yang-Mills theory on T 2n that are diagonal and constant, extending early work of Van Baal on T 4. The spectrum of fluctuations is determined and the eigenfunctions are given explicitly in terms of theta functions on tori. We show the relevance of the analysis to higher dimensional D-branes and discuss applications of the results in string theory...