ar X iv : h ep - p h / 96 05 20 5 v 1 2 M ay 1 99 6 HU - SEFT R 1996 - 11 QCD Coupling Constant at Finite Temperature ∗

ar X iv : h ep - p h / 96 05 28 2 v 1 1 1 M ay 1 99 6 TWO TOPICS IN PARTICLE - ANTIPARTICLE MIXING

ar X iv : h ep - p h / 96 05 31 0 v 1 1 5 M ay 1 99 6 O ( α 2 G F m 2 t ) Contributions to H → γγ

The rare decay H → γγ is a promising detection channel for an intermediate mass Higgs boson. We compute its two-loop O(αGFm 2 t ) correction in the standard model and find that it is much smaller than the corresponding QCD correction. The analogous correction to the amplitude for gg → H is recovered as a special case. The generalization of our result to other models is also briefly indicated.

ar X iv : h ep - t h / 96 05 13 9 v 1 2 1 M ay 1 99 6 Differential Renormalization of QCD in the Background - Field Method

A short outline is given on the application of differential regularization to QCD in the background-field method. The derivation of the propagators in the background gluon field as short-distance expansions is described and the renormalization of the theory is mentioned.

ar X iv : h ep - t h / 96 05 08 6 v 1 1 3 M ay 1 99 6 Curvature expansion for the background – induced gluodynamics string

Using cumulant expansion for an averaged Wilson loop we derive an action of the gluodynamics string in the form of a series in powers of the correlation length of the vacuum. In the lowest orders it contains the Nambu–Goto term and the rigidity term with the coupling constants computed from the bilocal correlator of gluonic fields. Some higher derivative corrections are calculated.

ar X iv : h ep - p h / 96 05 42 4 v 1 2 8 M ay 1 99 6 More nonperturbative corrections to the fine and hyperfine splitting in the heavy quarkonium

More nonperturbative corrections to the fine and hyperfine splitting in the heavy quarkonium Abstract The leading nonperturbative effects to the fine and hyperfine splitting (for n=2) have been calculated recently. We point out that a contribution of the same order O(Λ 4 QCD /m 3 α 2 s) has been overlooked. We calculate it in this paper.