Study of $$K^+ \rightarrow \pi ^{0} e^{+} \nu \gamma $$ decay with OKA setup

A. Yu. Polyarush, S. A. Akimenko, A. V. Artamonov, A. M. Blik, V. S. Burtovoy, V. N. Bychkov, S. V. Donskov, V. A. Duk, A. P. Filin, S. N. Filippov, A. M. Gorin, E. N. Gushchin (+25 others)
2021 European Physical Journal C: Particles and Fields  
AbstractResults of a study of the $$K^+ \rightarrow \pi ^{0} e^{+} \nu \gamma $$ K + → π 0 e + ν γ decay at OKA setup are presented. More than 32,000 events of this decay are observed. The differential spectra over the photon energy and the photon–electron opening angle in kaon rest frame are presented. The branching ratios, normalized to that of $$K_{e3}$$ K e 3 decay are calculated for different cuts on $$E^*_\gamma $$ E γ ∗ and $$cos\Theta ^{*}_{e\gamma }$$ c o s Θ e γ ∗ . In particular, the
more » ... branching ratio for $$E^{*}_{\gamma }>30$$ E γ ∗ > 30 MeV and $$\Theta ^{*}_{e \gamma }>20^{\circ }$$ Θ e γ ∗ > 20 ∘ is measured R = $$\frac{Br(K^+ \rightarrow \pi ^{0} e^{+} \nu _{e} \gamma ) }{Br(K^+ \rightarrow \pi ^{0} e^{+} \nu _{e})} $$ B r ( K + → π 0 e + ν e γ ) B r ( K + → π 0 e + ν e ) = = (0.587±0.010(stat.)±0.015(syst.))$$\times 10^{-2}$$ × 10 - 2 , which is in a good agreement with ChPT $$O(p^{4})$$ O ( p 4 ) calculations.
doi:10.1140/epjc/s10052-021-08895-2 fatcat:wzbwof4chfaank3gmvssj2ncde