T. Akaishi, H. Asano, X. Chen, A. Clozza, C. Curceanu, R. Del Grande, C.D. Han, T. Hashimoto, M. Iliescu, Kentaro Inoue, S. Ishimoto, K. Itahashi, M. Iwasaki, Y. Ma, R. Murayama, H. Noumi, H. Ohnìshì, S Okada, H. Outa, K. Piscicchia, Akira Sakaguchi, F. Sakuma, Masaki Sato, A. Scordo, K. Shirotori, D. Sirghi, Florin Sirghi, S. Suzuki, K. Tanida, T. Toda, T. Yamaga, X. Q. Yuan, P. Zhang, Y.P. Zhang, H. Zhang
Light $s$-shell hypernuclei ($^{3,4}_Λ\text{H}$) and their ground-state properties are crucial benchmarks in hypernuclear physics. In particular, comparing the production cross sections of $^{3}_Λ\text{H}$ and $^{4}_Λ\text{H}$ provides insights into the $ΛN$ interaction in different isospin configurations, which can help address recent discrepancies in the reported $Λ$ binding energy of hypertriton. We present the first measurement of the production cross sections for $^{3}_Λ\text{H}$ and $^{4}_Λ\text{H}$ using the in-flight $(K^-, π^0)$ reaction at a beam momentum of 1.0 GeV/$c$ with an identical experimental setup. The production cross sections in the laboratory frame, for the angular range from 0$^{\circ}$ to 20$^{\circ}$, are measured to be $15.0~\pm~2.6~(\text{stat.})~^{+2.4}_{-2.8}~(\text{syst.})~μ\text{b} $ and $49.9~\pm~2.1~(\text{stat.})~^{+7.8}_{-8.0}~(\text{syst.})~μ\text{b}$ for the ground-state of $^{3}_Λ\text{H}$ and $^{4}_Λ\text{H}$, respectively. Using the ratio of these cross sections and comparing it with theoretical calculations, we evaluate the $Λ$ binding energy of hypertriton, yielding a value consistent with the picture of a loosely bound system.