Precise lifetime measurement of Λ4H hypernucleus using in-flight 4He(K

Takao Akaishi, H. Asano,Xiao Chen, A. Clozza, C. Curceanu,R. Del Grande, C. Guaraldo, C. Han, T. Hashimoto, M. Iliescu,Kentaro Inoue,S. Ishimoto, K. Itahashi, M. Iwasaki,Y. Ma,Marco Miliucci, R. Murayama, H. Noumi, H. Ohnìshì, S. Okada,H. Outa, K. Piscicchia,A. Sakaguchi, F. Sakuma,Masaharu Sato, A. Scordo,K. Shirotori, D. Sirghi, F. Sirghi, S. Suzuki, K. Tanida,Taiga Toda, Miwa Tokuda, T. Yamaga,Xiaohui Yuan, P. Zhang, Y. Zhang, H. Zhang

We present a new measurement of the Λ4H hypernuclear lifetime using in-flight K− + 4He → Λ4H + π0 reaction at the J-PARC hadron facility. We demonstrate, for the first time, the effective selection of the hypernuclear bound state using only the γ-ray energy decayed from π0. This opens the possibility for a systematic study of isospin partner hypernuclei through comparison with data from (K−, π−) reaction. As the first application of this method, our result for the Λ4H lifetime, τ(HΛ4)=206±8(stat.)±12(syst.)ps, is one of the most precise measurements to date. We are also preparing to measure the lifetime of the hypertriton (Λ3H) using the same setup in the near future.