Polarization in K^+ → π^+μ^+μ^−

Abstract

The parity violating asymmetry [(Γ_R−Γ_L)/(Γ_R+Γ_L)], where Γ_R and Γ_L are the rates to produce right handed and left handed μ^+ in the decay K^+ → π^+μ^+μ^−, is discussed. We examine the contribution to this asymmetry from the interference of the "Z-penguin" and "W-box" with the standard one-photon contribution in the minimal standard model and in models with two Higgs doublets. The asymmetry is sensitive to extensions of the Higgs sector. Time reversal violating polarization effects are also considered. We show that the polarization of the μ^+ perpendicular to the μ^+μ^− decay plane is small.

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