Regular Article - Theoretical Physics
Analyticity constraints on the strangeness changing vector current and applications to τ→Kπντ and τ→Kππντ
Groupe de Physique Théorique, Institut de Physique Nucléaire, CNRS/IN2P3, Université Paris-Sud 11, 91406, Orsay, France
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Revised: 22 October 2007
Published online: 29 November 2007
We discuss matrix elements of the strangeness changing vector current using their relation, due to analyticity, with πK scattering in the P-wave. We take into account experimental phase-shift measurements in the elastic channel as well as results, obtained by the LASS collaboration, on the details of inelastic scattering, which show the dominance of two quasi-two-body channels at medium energies. The associated form factors are shown to be completely determined, up to one flavor symmetry breaking parameter, imposing boundary conditions at t=0 from chiral and flavor symmetries and at t→∞ from QCD. We apply the results to the τ→Kπντ and τ→Kππντ amplitudes and compare the former to recent high statistics results from B factories.
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