New Measurement of the Properties of the Rare Decay $K^{+} \to π^{+} e^{+} e^{-}$

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29 November 1999

journal article
research article
Published by American Physical Society (APS) in Physical Review Letters

Vol. 83 (22) , 4482-4485
https://doi.org/10.1103/physrevlett.83.4482

Abstract

A low-background sample of 10 300 events has been collected for the decay mode

K^{+} \to π^{+} e^{+} e^{-}

by experiment E865 at the Brookhaven Alternating Gradient Synchrotron. The branching ratio is measured to be

[2.94 \pm 0.05 (stat) \pm 0.13 (syst) \pm 0.05 (model)] \times 10^{- 7}

, the vector nature of this decay is firmly established, and the decay form factor

f (z) {= f}_{0} (1 + δ z) ({z = M}_{ee}^{2} {/ m}_{K}^{2})

is determined to have

δ = 2.14 \pm 0.13 \pm 0.15

. The experiment is described and results discussed in the context of chiral perturbation theory.

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