$B_K$ from twisted mass QCD

Abstract

We present some preliminary results for $B_K$ at $\beta =6.0$, using the twisted mass QCD formalism for the computation of bare matrix elements of the $\Delta S=2$ operator. The main advantage of the method is that mixing with other $d=6$ operators under renormalisation is avoided. Moreover the operator renormalisation is performed in the Schrödinger functional (SF) framework, using earlier results of our collaboration for the corresponding step scaling function.

Comments: Lattice2003(matrix), 3 pages, 2 figures