Evidence for a narrow S = +1 baryon resonance in photoproduction from the neutron.
The gamman-->K(+)K(-)n reaction on 12C has been studied by measuring both K+ and K- at forward angles. A sharp baryon resonance peak was observed at 1.54+/-0.01 GeV/c(2) with a width smaller than 25 MeV/c(2) and a Gaussian significance of 4.6sigma. The strangeness quantum number (S) of the baryon resonance is +1. It can be interpreted as a molecular meson-baryon resonance or alternatively as an exotic five-quark state (uuddsmacr;) that decays into a K+ and a neutron. The resonance is consistent with the lowest member of an antidecuplet of baryons predicted by the chiral soliton model.
Nakano
T
T
Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047, Japan.
Ahn
D S
DS
Ahn
J K
JK
Akimune
H
H
Asano
Y
Y
Chang
W C
WC
Daté
S
S
Ejiri
H
H
Fujimura
H
H
Fujiwara
M
M
Hicks
K
K
Hotta
T
T
Imai
K
K
Ishikawa
T
T
Iwata
T
T
Kawai
H
H
Kim
Z Y
ZY
Kino
K
K
Kohri
H
H
Kumagai
N
N
Makino
S
S
Matsumura
T
T
Matsuoka
N
N
Mibe
T
T
Miwa
K
K
Miyabe
M
M
Miyachi
Y
Y
Morita
M
M
Muramatsu
N
N
Niiyama
M
M
Nomachi
M
M
Ohashi
Y
Y
Ooba
T
T
Ohkuma
H
H
Oshuev
D S
DS
Rangacharyulu
C
C
Sakaguchi
A
A
Sasaki
T
T
Shagin
P M
PM
Shiino
Y
Y
Shimizu
H
H
Sugaya
Y
Y
Sumihama
M
M
Toyokawa
H
H
Wakai
A
A
Wang
C W
CW
Wang
S C
SC
Yonehara
K
K
Yorita
T
T
Yoshimura
M
M
Yosoi
M
M
Zegers
R G T
RG