H-dibaryon and hypernucleus formation in the Ξ-12C reaction at rest

KEK-PS E224 Collaboration

Ahn J.K.

Aoki S.

Chung K. S.

Chung M. S.

En'yo H.

Fukuda T.

Funahashi H.

Goto Y.

Higashi A.

Ieiri M.

Iijima T.

Iinuma Masataka

Imai K.

Itow Y.

Lee J. M.

Makino S.

Masaike A.

Matsuda Y.

Matsuyama Y.

Mihara S.

Nagoshi C.

Nomura I.

Park I. S.

Saito N.

Sekimoto M.

Shin Y. M.

Sim K. S.

Susukita R.

Takashima R.

Takeutchi F.

Tlustý P.

Weibe S.

Yokkaichi S.

Yoshida K.

Yoshida M.

Yoshida T.

Yamashita S.

Physical Review C - Nuclear Physics

Stopped-Ξ-12C reactions have been investigated with respect to H-dibaryon and hypernucleus formation with a scintillating fiber detector. Out of 5.5×103 tagged Ξ- particles via the (K-,K+) reaction we obtained 72 stopping Ξ- events with 6.7+1.1-1.4 background events after imposing kinematic constraints. Hypernuclear production has been studied by observing free Λ decays in the stopped-Ξ- reactions. From the observed Λ momentum spectrum, we have found the hypernuclear production rates to be 18±13, 65±6, and 17±12 % for double/twin-A hypernucleus, single-Λ hypernucleus, and no hypernucleus cases, respectively. With the same sample, we set upper limits on R (stopped-Ξ-12C→HX /stopped-Ξ-12C→ all) for H decaying into Λn, Σ-p, and Λpπ-, for H masses just below ΛΛ mass threshold and for H lifetime range 10-11≤τH≤10-8 s. The upper limits on R are ∼0.1-0.2, assuming all of the H decay into each decay mode. Our results give a tight constraint on the existence of the bound H, in comparison with the theoretical estimates of Aerts and Dover, albeit with different target nuclei.

英語

American Physical Society

Copyright (c) 2000 The American Physical Society.

[ISSN] 0556-2813

[DOI] 10.1103/PhysRevC.62.055201

[NCID] AA00773613

[DOI] http://dx.doi.org/10.1103/PhysRevC.62.055201