Speaker
Описание
The talk is devoted to three latest results.
First is a search for the axion like particles in the decay
$K^+ \to \pi^+ \pi^0 a$:
A high statistics data sample of the K+ decays is recorded by the OKA collaboration. A missing mass analysis
is performed to search for a light invisible pseudoscalar axion-like particle (ALP) in the decay $K^+ \to \pi^+ \pi^0 a$. No signal is observed, the upper limits for the branching ratio of the decay are calculated. The 90% confidence level upper limit is changing from $2.5\times10^{-6}$ to $2\times10^{-7}$ for the ALP mass from 0 to 200 MeV.
Second is $K^+ \to \mu^+ \nu g$ decay study and measurement of FV - FA :
A new precise measurement of the vector and axial-vector form factor diff erence FV − FA in the $K^+ \to \mu^+ \nu_{\mu} \gamma$ decay is presented. About 144 K events of $K^+ \to \mu^+ \nu_{\mu} \gamma$ are selected in the OKA experiment.
The result is FV − FA = 0.135 ± 0.017(stat) ± 0.024(syst). The result is considered as preliminary.
The third is $K^+ \to \mu^+ \nu \pi^0 g$ decay study.
The $K^+ \to \pi^0 \mu^+ \nu \gamma (K_{\mu 3\gamma})$ is measured with OKA setup at the RF-separated 17.7 GeV/c momentum kaon beam of the U-70 accelerator. The data corresponds to the flux of $2.62 \times 10^10$ «live» kaons entering the decay volume. More than 900 signal events are found with 30-60 MeV energy of the emitted photon in the rest frame of the decaying kaon. Using $4.48 \times 10^6$ events of the decay $K^+ \to \pi^0 \mu^+ \nu (K_{\mu 3})$ the branching ratio Br(Kµ3γ)/Br(Kµ3) is found to be (4.45 ± 0.25(stat)) × 10$^{−4}$. From this value, using Br($K_{\mu 3}$) = 3.352% we get Br($K_{\mu 3\gamma}$) = (1.492 ± 0.085(stat)) × 10$^{−5}$. Our result is preliminary, with systematic errors being estimated.
