XXXV International Workshop on High Energy Physics "From Quarks to Galaxies: Elucidating Dark Sides"

Recent results on kaon physics from the OKA experimen

29 нояб. 2023 г., 15:35

45m

Particle Physics: Experiment and Phenomenology Afternoon session 29/11/2023

Speaker

Vladimir Obraztsov (NRC KI - Logunov IHEP, Protvino)

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 $2.5\times {10}^{-6}$ to $2\times {10}^{-7}$ 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 $2.62\times {10}^{1}0$ «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.

Presentation materials

OKA_IWHEP23.pdf