Experimental study of

Quasi-bound systems of antikaon and nucleus, K̅ -nuclei, have been considered as a natural extension of the interpretation that Λ(1405) is the K̅-N hadronic molecule. The lightest K̅-nucleus, K̅NN quasi-bound state, is particularly important to be investigated for confirmation of the existence of such an exotic nuclear state containing a meson. We conducted an experiment, JPARC E15, to search for K̅NN(Iz=+1/2) by the in-flight K− induced reaction on 3He, and finally observed a clear signal of K̅NN(Iz=+1/2) for the first time. To robustly confirm the existence of K̅-nuclei, we have planned systematic measurements for various K̅ -nuclei at J-PARC

1-Methylcyclopropene Maintains Firmness and Peel Color and Reduces Decay Area of Artificially Wounded Fruits in Mature Japanese Pear (Pyrus pyrifolia Nakai ‘Shizukisui’)

Recently, there has been an increasing need to prolong the quality of matured fruits to promote the distribution of fresh fruits to consumers and processing facilities. Studies have shown that 1-methylcyclopropene (1-MCP), an inhibitor of ethylene, can maintain the firmness and quality of several fruits for a long duration. Therefore, the aim of this study was to examine the effect of 1-MCP treatment on the firmness, rind color, and decay rate of the Japanese pear ‘Shizukisui’. Results showed that 1-MCP treatment alone and 1-MCP treatment after precooling significantly maintained the firmness of mature fruits compared with untreated fruits. However, the presence or absence of ethylene addition did not significantly affect fruit firmness; moreover, 1-MCP treatment after precooling tended to reduce moisture loss in immature fruits. Regarding the peel color of the fruits, 1-MCP treatment alone and 1-MCP after precooling treatment increased the L*, b*, and C* values of mature fruits but reduced the values in immature fruits. Compared with the control group, the 1-MCP treatment caused a decrease in the decay area of wounded ‘Shizukisui’ and ‘Kosui’ fruits and decreased the decay rate of wounded ‘Kosui’. Overall, this study showed that 1-MCP treatment maintained the firmness and peel color of Japanese pear and reduced its decay rate

Comparison of

Recent heavy-ion collision experiments reported a surprisingly short lifetime for the hypertriton, which has been recognized as the hypertriton lifetime puzzle. Our J-PARC E73 experiment contributes to solve this puzzle with an independent experimental method by employing 3He(K−, π0) 3ΛH reaction. In this contribution, we will demonstrate our capability to provide 3ΛH binding energy information by deriving the production cross section ratio, σ3ΛH/σ4ΛH. The production cross section data for 3ΛH and 4ΛH are already available as the pilot run of E73 experiment and data analysis is in progress

Study of the elementary (K−, n) reactions to search for the K¯NN bound state via the 3He (K−, n) reaction at J-PARC

We have searched for the simplest kaonic nuclear state, K̄NN, using the in-flight 3He (K-, n) reaction at the J-PARC hadron experimental facility. In the semi-inclusive neutron missing-mass spectrum at θnlab=0°, an excess of yield was observed just below the K- pp mass-threshold, which cannot be explained by any elementary reactions [PTEP 2015, 061D01]. To understand the missing-mass spectrum of 3He (K-, n) X, we investigated the elementary (K-, n) reactions using hydrogen and deuterium targets. The p (K-, n) X missing-mass spectrum was well described by the charge-exchange reaction. However, in the d (K-, n) X spectrum, we observed an excess of yield just below the K- p mass-threshold, which was similar to that in the 3He (K-, n) X spectrum

Summary of the

The possible existence of deeply-bound $\bar K$-nuclear bound states, kaonic nuclei, has been widely discussed as products of the strongly attractive $\bar K$N interaction in I = 0 channels. Investigations of those exotic states will provide us unique information of the $\bar K$N interaction below the threshold, which is still not fully understood so far. Recently, we observed the simplest kaonic nuclei, $\bar K$NN, having a much deeper binding energy than normal nuclei via inflight (K−, N) reactions at the J-PARC E15 experiment. For further studies, we have proposed a series of experimental programs for the systematic investigation of light kaonic nuclei, from $\bar K$N (Λ(1405)) to $\bar K$NNNN. We will measure the $\bar K$NNN (A = 3) system at the new experiment approved as J-PARC E80, as a first step toward a comprehensive study