Lattice matrix elements confronting the experimental value of eps'/eps

Abstract

A new lattice estimate of K -> 2 pi transitions claims, contrary to all other computations, that the hadronic matrix element for the gluon penguin operator Q_6 has opposite sign and, in addition, is much larger than the vacuum saturation approximation. We comment under what conditions (if any) it is possible to reconcile this lattice result with the experimental value of eps'/eps. The dramatic impact of new physics in the kaon system that seems to be required is not easily accommodated within our present theoretical understanding.

Comments: JHEP.cls, 1 figure