Speaker
Dr
Tadashi Hashimoto
(RIKEN)
Description
The investigation of antikaon(Kbar) nuclear bound states is one of the hottest topics in strangeness nuclear physics since observations of such states give quite unique information on the sub-threshold KbarN interaction[1]. However, the existence of Kbar nuclear-states has not been established so far, even for the simplest system, K ̄pp[2].
Our approach is to search for the K ̄pp bound state via the 3He(K ̄,n) reaction at a kaon momentum of 1 GeV/c(J-PARC E15[3]). In this reaction, most of background processes such as multi-nucleon processes and hyperon decays are separable thanks to the inflight kinematics. A helium-3 target enlarges the chance to reconstruct full kinematics of the reaction by detecting the expected decay, “K ̄pp” → Λp → π ̄pp. To realize such a measurement, we constructed a spectrometer system composed of a beam spectrometer, a large acceptance cylindrical detector system (CDS) surrounding a liquid helium-3 target, and a forward neutron detection system at the K1.8BR experimental area in the J-PARC hadron experimental facility[4].
The first physics data were taken in May, 2013, with ∼5 × 10^9 kaons on the helium-3 target. The main goal of the data-taking was to search for a signal of the K ̄pp bound state in the (semi-)inclusive neutron analysis, which requires much less kaon irradiation than the exclusive Λpn measurement. The new spectrometer system worked well as expected, and we successfully obtained the 3He(K ̄,n)X missing-mass spectrum at forward angle with a resolution of ∼10 MeV/c^2 at around the K ̄ + p + p mass threshold. The spectrum was obtained by requiring at least one charged track in the CDS to reconstruct the vertex position, and has a good signal-to-noise ratio of ∼100 : 1 at the quasi-free K ̄“N”→KbarN reaction peak. The analysis will soon be finalized.
In this contribution, the latest results of the first physics data in J-PARC E15 will be discussed, focusing on the K ̄pp bound region in the semi-inclusive 3He(K ̄,n) spectrum.
[1] Y. Akaishi and T. Yamazaki. Phys. Rev. C 65 044005 (2002).
[2] M. Agnello, et al., Phys. Rev. Lett 94, 212303 (2005);
T. Yamazaki, et al., Phys. Rev. Lett 104, 132502 (2010);
L. Fabbietti, et al., Nucl. Phys. A 914, 60 (2013);
A. O. Tokiyasu et al. Phys. Lett. B 728, 616 (2014).
[3] M. Iwasaki and T. Nagae (E15 collaboration), J-PARC E15 proposal,
(http://j-parc.jp/NuclPart/pac 0606/pdf/p15-Iwasaki.pdf).
[4] K. Agari, et al., Prog. Theor. Exp. Phys. 02B011 (2012).
Primary author
Dr
Tadashi Hashimoto
(RIKEN)
Co-authors
Dr
Akihisa toyoda
(KEK)
Dr
Alessandro scordo
(INFN Frascati)
Dr
Antonio romero vidal
(INFN Frascati)
Prof.
Atsushi sakaguchi
(Osaka University)
Dr
Barbara Wuenschek
(Stefan-Meyer-Institut)
Dr
Carlo guaraldo
(INFN Frascati)
Prof.
Catalina Curceanu
(INFN Frascati)
Dr
Dai tomono
(Kyoto University)
Dr
Diana Sirghi
(INFN Frascati)
Dr
Diego faso
(INFN Torino)
Prof.
Eberhard widmann
(Stefan-Meyer-Institut)
Dr
Florin Sirghi
(INFN Frascati)
Dr
Fuminori sakuma
(RIKEN)
Prof.
George Beer
(University of Victoria)
Dr
Haruhiko outa
(RIKEN)
Dr
Hexi Shi
(Stefan-Meyer-Institut)
Dr
Hideyuki tatsuno
(The University of Tokyo)
Dr
Hiroaki ohnishi
(RIKEN)
Prof.
Hiroshi Kou
(Tokyo Institute of Technology)
Prof.
Hiroyuki Noumi
(RCNP, Osaka University)
Dr
Hiroyuki fujioka
(Kyoto University)
Prof.
Hyoungchan Bhang
(Seoul National University)
Dr
Johann marton
(Stefan-Meyer-Institut)
Prof.
Johann zmeskal
(Stefan-Meyer-Institut)
Dr
Ken suzuki
(Stefan-Meyer-Institut)
Dr
Kenta itahashi
(RIKEN)
Mr
Kentaro inoue
(Osaka University)
Prof.
Kiyoshi tanida
(Seoul National University)
Dr
Kristian piscicchia
(INFN Frascati)
Dr
Kyo tsukada
(Tohoku University)
Dr
Luigi busso
(INFN Torino)
Mr
Makoto tokuda
(Tokyo Institute of Technology)
Dr
Marco poli lener
(INFN Frascati)
Dr
Mario Bragadireanu
(INFN IH)
Ms
Masaaki iwai
(KEK)
Dr
Masaharu sato
(RIKEN)
Prof.
Masahiko iwasaki
(RIKEN)
Dr
Masami iio
(KEK)
Dr
Michael Cargnelli
(Stefan-Meyer-Institut)
Dr
Michiko sekimoto
(KEK)
Dr
Mihai iliescu
(INFN Frascati)
Dr
Ombretta morra
(INFN Torino)
Dr
Oton Vazquez Doce
(INFN Frascati)
Dr
Paul Buehler
(Stefan-Meyer-Institut)
Mr
Qi Zhang
(RIKEN)
Prof.
Ryugo hayano
(The University of Tokyo)
Prof.
Seonho Choi
(Seoul National University)
Dr
Shigeru ishimoto
(KEK)
Mr
Shingo kawasaki
(Osaka University)
Dr
Shinji okada
(RIKEN)
Mr
Shoji suzuki
(KEK)
Prof.
Shuhei Ajimura
(RCNP, Osaka University)
Mr
Shun enomoto
(RCNP, Osaka University)
Dr
Takashi Ishikawa
(The University of Tokyo)
Dr
Takatoshi suzuki
(The University of Tokyo)
Mr
Takumi yamaga
(Osaka University)
Prof.
Tomofumi nagae
(Kyoto University)
Dr
Tomoichi ishiwatari
(Stefan-Meyer-Institut)
Prof.
Tomokazu fukuda
(Osaka Electro-Communication University)
Mr
Toshihiko hiraiwa
(RCNP, Osaka University)
Prof.
Toshimitsu yamazaki
(The University of Tokyo/RIKEN)
Prof.
Yasuyuki matsuda
(The University of Tokyo)
Mr
Yosuke ishiguro
(Kyoto University)
Dr
Yue Ma
(RIKEN)
Ms
Yuko kato
(RIKEN)
Mr
Yuta sada
(Osaka University)
Dr
Yutaka mizoi
(Osaka Electro-Communication University)
Mr
Yuya fujiwara
(The University of Tokyo)
