Precise lifetime measurement of ${}_{\hat{I}}^4›$H hypernucleus using in-flight ${}^4$He$(K^{-},\ddot{I}{€}^0{)}_{\hat{I}}^4›$H reaction

Abstract

We present a new measurement of the ${}_{\hat{I}}^4›$H hypernuclear lifetime using in-flight $K^{-}$ + ${}^4$He $\to$ ${}_{\hat{I}}^4›$H + $\ddot{I}{€}^0$ reaction at the J-PARC hadron facility. We demonstrate, for the first time, the effective selection of the hypernuclear bound state using only the ${\hat{I}}^3$-ray energy decayed from $\ddot{I}{€}^0$. This opens the possibility for a systematic study of isospin partner hypernuclei through comparison with data from ($K^{-}$, $\ddot{I}{€}^{-}$) reaction. As the first application of this method, our result for the ${}_{\hat{I}}^4›$H lifetime, $\ddot{I}„{(}_{\hat{I}}^4›\mathrm{H})=206\pm 8(stat.)\pm 12(syst.)\mathrm{ps}$, is one of the most precise measurements to date. We are also preparing to measure the lifetime of the hypertriton (${}_{\hat{I}}^3›$H) using the same setup in the near future.