Status report on weak matrix element calculations

ar X iv : h ep - l at / 9 51 20 06 v 1 4 D ec 1 99 5 1 Status Report on Weak Matrix Element Calculations ∗

This talk presents results of weak matrix elements calculated from simulations done on 170 32 × 64 lattices at β = 6.0 using quenched Wilson fermions. We discuss the extraction of pseudoscalar decay constants fπ, fK , fD, and fDs , the form-factors for the rare decay B → K ∗γ, and the matrix elements of the 4-fermion operators relevant to BK , B7, B8. We present an analysis of the various sourc...

Reliability of K → ππ matrix element calculations

I demonstrate that the short distance contribution to K → ππ decays must be supplemented with large distance effects. A hybrid calculation is outlined based on QCD diagrams supplemented by chiral contributions and π–π phaseshifts.

Anatomy of a Weak Matrix Element

Although the weak nonleptonic amplitudes of the Standard Model are notoriously difficult to calculate, we have produced a modified weak matrix element which can be analyzed using reliable methods. This hypothetical nonleptonic matrix element is expressible in terms of the isovector vector and axialvector spectral functions ρV(s) and ρA(s), which can be determined in terms of data from tau lepto...

On Nonlinear Preservers of Weak Matrix Majorization

Status Report of NNLO QCD Calculations

We review recent progress in next-to-next-to-leading order (NNLO) perturbative QCD calculations with special emphasis on results ready for phenomenological applications. Important examples are new results on structure functions and jet or Higgs boson production. In addition, we describe new calculational techniques based on twistors and their potential for efficient calculations of multiparticl...