Forward-backward asymmetry inK+→π+l+

Abstract

We study the forward-backward asymmetries in the decays of K + → π + ℓ + ℓ − (ℓ = e and µ) in the presence of scalar or tensor terms. We find that with the scalar (tensor) type interaction the asymmetry can be up to O(10 −3 ) (O(10 −1 )) and arbitrary large for the electron and muon modes, respectively, without conflict with the experimental data. We also discuss the cases in the minimal supersymmetric standard model where the scalar terms can be induced. In particular we show that the asymmetry in K + → π + µ + µ − can be as large as O(10 −3 ) in the large tan β limit, which can be tested in future experiments such as CKM at Fermilab.

New measurement of the K±→π±μ+μ− decay

“…It corresponds to an upper limit of |A F B | < 2.3 × 10 −2 at 90% CL. The achieved precision does not reach the upper limits for the SM contribution via the two-photon intermediate state K ± → π ± γ * γ * → π ± µ + µ − [29] and MSSM contribution [18], which are both of the order of 10 −3 .…”

“…A F B is expected to be sensitive to non-SM effects, and to be enhanced in the K πµµ decay with respect to the K πee decay [18]. Due to the limited size of the data sample, only the asymmetry integrated over the z variable is considered in the present analysis.…”

The Higgs Penguin and Its Applications: An Overview

“…This category includes the master application have been studied in [58], [59] and [60], respectively, and the lepton polarization asymmetry in B → ll or K → ll decays has been studied in [61] and [62], respectively.…”

Measurement of the FCNC decays $K^{\pm} \rightarrow \pi^{\pm} \ell^+ \ell^-$ from NA48

“…Unlike the K ± → π ± e + e − case, the full kinematic z range is accessible, and effects of radiative corrections are suppressed. In addition to spectrum, rate and CPV measurements, the first measurement of the forward-backward asymmetry, which can be enhanced with respect to K ± → π ± e + e − in both SM and MSSM [15], is performed.…”