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C.h.Kim, C.T.Sachrajda
(Submitted on 16 Mar 2010)
Abstract: We propose a new method to evaluate the Lellouch-Luescher factor which relates the Delta I=3/2 K -> pi pi matrix elements computed on a finite lattice to the physical (infinite-volume) decay amplitudes. The method relies on the use of partially twisted boundary conditions, which allow the s-wave pi pi phase shift to be computed as an almost continuous function of the centre-of-mass relative momentum and hence for its derivative to be evaluated. We successfully demonstrate the feasibility of the technique in an exploratory computation.
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