ar X iv : c on d - m at / 9 70 90 44 v 1 4 S ep 1 99 7 Geometrical Properties of Cumulant Expansions

ar X iv : c on d - m at / 9 60 90 54 v 1 5 S ep 1 99 6 Cumulant Expansions and the Spin - Boson Problem ∗

The dynamics of the dissipative two-level system at zero temperature is studied using three different cumulant expansion techniques. The relative merits and drawbacks of each technique are discussed. It is found that a new technique, the non-crossing cumulant expansion, appears to embody the virtues of the more standard cumulant methods. PACS-number(s): 05.30.-d, 05.40.+j, 72.15.Qm submitted to...

ar X iv : h ep - l at / 9 70 90 10 v 1 5 S ep 1 99 7 1 HUPD - 9715 NRQCD Results on Form Factors ∗

We report results on fB and semi-leptonic B decay form factors using NRQCD. We investigate 1/M scaling behavior of decay amplitudes. For fB Effect of higher order relativistic correction terms are also studied.

ar X iv : q - a lg / 9 70 90 01 v 1 1 S ep 1 99 7 Bilinear identity for q - hypergeometric integrals

ar X iv : c on d - m at / 9 90 90 44 v 1 3 S ep 1 99 9 Systematic low temperature expansion in Ginzburg - Landau model

Consistent perturbation theory for thermodynamical quantities in strongly type II superconductors in magnetic field at low temperatures is developed. It is complementary to the existing expansion valid at high temperatures. Magnetization and specific heat are calculated to two loop order and compare well with existing Monte Carlo simulations, other theories and experiments. Typeset using REVTEX 1

ar X iv : h ep - t h / 99 12 07 5 v 1 9 D ec 1 99 9 SMI - 15 - 99 Two - Loop Diagrams in Noncommutative φ 44 theory

Explicit two-loop calculations in noncommutative ϕ 4 4 theory are presented. It is shown that the model is two-loop renormalizable.