J-PARC E27 Experiment to Search for a K−pp Bound State

Ichikawa, Y.; Nagae, T.; Bhang, H.; Bufalino, S.; Ekawa, H.; Evtoukhovitch, P.; Feliciello, A.; Fujioka, Hiroyuki; Hasegawa, Shoichi; Hayakawa, Shuhei; Honda, Ryumon; Hosomi, K.; Ishimoto, S.; Joo, C.; Kanatsuki, Shunsuke; Kiuchi, R.; Koike, T.; Kumawat, H.; Matsumoto, Y.; Miwa, K.; Moritsu, Manabu; Naruki, M.; Niiyama, M.; Nozawa, Y.; Ota, Ryosuke; Sakaguchi, A.; Sako, H.; Самойлов, В. Н.; Sato, Susumu; Shirotori, K.; Sugimura, Hitoshi; Suzuki, S.; Takahashi, T.; Takahashi, T.; Tamura, H.; Tanaka, Toshiyuki; Tanida, K.; Tokiyasu, A. O.; Tsamalaidze, Z.; Roy, B. J.; Ukai, M.; Yamamoto, T. O.; Yang, S. B.

doi:10.7566/jpscp.8.021020

Cited by 6 publications

(14 citation statements)

References 16 publications

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“…We have made a comparison of the current results with experimental results searching for the K − pp quasi-bound state. By a naive comparison, it is quite obvious that our results can not explain the results of earlier experiments such as FINUDA [8], DISTO [9], and J-PARC E27 [10], which reported signals around 100 MeV below theKNN threshold. As for the latest result of J-PARC E15 (second run, J-PARC E15 2nd ), the reported binding energy, ∼ 50 MeV [16], could be explained by the results calculated with phenomenological potential, and somehow by our result obtained with a chiral-type potential employing the particle picture.…”

Section: Summary and Future Prospectscontrasting

confidence: 80%

“…The symbol of a red square represents the result of J-PARC E15 2nd experiment, which is plotted with a interpretation that the observed signal is a K − pp quasi-bound state. It is noted that results of other earlier experiments (FINUDA [8], DISTO [9] and J-PARC E27 [10]) can not be plotted on this figure because the reported binding energy is more than 90 MeV, if they are interpreted as a K − pp quasi-bound state.…”

Section: Discussionmentioning

confidence: 98%

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Fully coupled-channel study of K−pp resonance in a chiral SU(3)-based K¯N potential

2018

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Nuclear system with antikaons, so-called kaonic nuclei, has been a longstanding issue in strange nuclear physics and hadron physics, because they might have exotic nature; In particular, they could be a doorway to the dense matter due to the strong attraction between antikaon and nucleon. Among kaonic nuclei, the three-body system composed of two protons and a single K − meson, K − pp, is the most essential. In this article 1 , we will report on the recent situation of K − pp studies in both theoretical and experimental sides. Afterwards, we will explain our latest study of the K − pp with a fully coupled-channel complex scaling method (Full ccCSM) using a chiral SU(3)-basedKN(-πY) potential. In Full ccCSM, the K − pp is completely treated as a resonant state of aKNN-πΣN-πΛN coupled-channel system. The energy dependence involved in the chiral potential is handled with a selfconsistent calculation in which two extreme ansatzes are examined: field picture and particle picture. With our chiral SU(3)-based potential constrained by the precise data of kaonic hydrogen atom (SIDDHARTA experiment), the K − pp resonance is obtained as a shallowly bound state measured from theKNN threshold with a narrow width, if the field picture is employed in the calculation: the binding energy is 14 − 28 MeV and half value of the mesonic decay width are 8 − 15 MeV. On the other hand, if the particle picture is employed, it is found that the binding energy could be as large as about 50 MeV, even though such a chiral potential is used. Based on these results of Full ccCSM calculation, we have discussed on the possibility for kaonic nuclei to form a dense matter and on the latest experimental result reported by J-PARC E15 collaboration.Thus, kaonic nuclei are expected to be an exotic system. In order to reveal the properties of kaonic nuclei, many researchers have focused on the K − pp, which is a three-body system composed of a single K − meson and two protons. Certainly, general kaonic nuclei might possess interesting properties. However, it is difficult to investigate such a strongly-interacting quantum many-body system. Therefore, before proceeding to general systems, the simple three-body system, K − pp, has been investigated eagerly from both theoretical and experimental sides. As mentioned in the previous paragraph, the Λ(1405) is a quasi-bound state of two-bodyKN system. In our viewpoint, the Λ(1405) is a building block of kaonic nuclei, and the K − pp is a prototype of kaonic nuclei, which means the most essential kaonic nucleus. The K − pp could be a bridge from the excited hyperon Λ(1405) to general systems of kaonic nuclei.The current situation of the K − pp study is as follows. There have been many experiments to search for the K − pp quasi-bound states. However, the results are different in each experiment. In an early experiment by FINUDA collaboration [8], a bump structure was reported in the observed Λp invariant-mass distribution at far below thē KNN threshold. In addition, DISTO [9] and J-PARC E27 [10] collaborations re...

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Section: Summary and Future Prospectscontrasting

confidence: 80%

Section: Discussionmentioning

confidence: 98%

Fully coupled-channel study of K−pp resonance in a chiral SU(3)-based K¯N potential

2018

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“…One step forward in the evaluation of the width was given in [21], where two-nucleonK absorption was explicitly considered. In that study a binding of [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] MeV was found, together with a width of the order of 80 MeV. The fact that the width is larger than the binding energy is shared by most of the theoretical approaches.…”

Section: Introductionmentioning

confidence: 99%

On the structure observed in the in-flight 3He(K−,Λp)n reaction at J-PARC

Sekihara

Oset

Ramos

2016

Prog. Theor. Exp. Phys.

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A theoretical investigation is done to clarify the origin of the peak structure observed near the K − pp threshold in the in-flight 3 He(K − , Λp)n reaction of the J-PARC E15 experiment, which could be a signal of the lightest kaonic nuclei, that is, the KN N (I = 1/2) state. For the investigation, we evaluate the Λp invariant mass spectrum assuming two possible scenarios to interpret the experimental peak. One assumes that the Λ(1405) resonance is generated after the emission of an energetic neutron from the absorption of the initial K − , not forming a bound state with the remaining proton. This uncorrelated Λ(1405)p system subsequently decays into the final Λp. The other scenario implies that, after the emission of the energetic neutron, a KN N bound state is formed, decaying eventually into a Λp pair. Our results show that the experimental signal observed in the in-flight 3 He(K − , Λp)n reaction at J-PARC is qualitatively well reproduced by the assumption that a KN N bound state is generated in the reaction, definitely discarding the interpretation in terms of an uncorrelated Λ(1405)p state.

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“…Following recent searches for aKNN I(J P )= 1 2 (0 − ) quasibound state (loosely termed K − pp) in Frascati [22,23], SPring-8 [24] and GSI [25,26], Iwasaki reported in MESON2016 on dibaryon candidates EPJ Web of Conferences from J-PARC Experiments E27 [27,28] and E15 [29,30], with binding energies given by…”

Section: Strange Dibaryonsmentioning

confidence: 99%

“…J-PARC E27 d(π + , K + )X missing-mass spectra at p π + = 1.69 GeV/c. Left: small-angle K + inclusive quasi-free spectrum [27]. Right: Σ 0 p decay branch of a pp coincidence spectrum [28].…”

Section: Strange Dibaryonsmentioning

confidence: 99%