Study of the decay $K^{+}\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^{+}{\hat{I}}^3$ in the OKA experiment

Abstract

A high statistics data sample of the decays of $K^{+}$ mesons to three charged particles was accumulated by the OKA experiment in 2012 and 2013. This allowed to select a clean sample of about 450 events with $K^{+}\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^{+}{\hat{I}}^3$ decays with the energy of the photon in the kaon rest frame greater than 30 MeV. The measured branching fraction of the $K^{+}\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^{+}{\hat{I}}^3$, with $E_γ^{*}$ > 30 MeV is $(0.71\pm 0.05)\times 10^{-5}$. The measured energy spectrum of the decay photon is compared with the prediction of the chiral perturbation theory to O$(p^4)$. A search for an up-down asymmetry of the photon with respect to the hadronic system decay plane is also performed.

9 pages, 7 figures, 1 table