Photoproduction of eta mesons off protons for 0.75 GeV<E(gamma)<3 GeV.
Total and differential cross sections for the reaction p(gamma,eta)p have been measured for photon energies in the range from 750 MeV to 3 GeV. The low-energy data are dominated by the S11 wave which has two poles in the energy region below 2 GeV. Eleven nucleon resonances are observed in their decay into peta. At medium energies we find evidence for a new resonance N(2070)D15 with (M,Gamma)=(2068+/-22, 295+/-40) MeV. At gamma energies above 1.5 GeV, a strong peak in the forward direction develops, signaling the exchange of vector mesons in the t channel.
Credé
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Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Nussallee 14-16, D-53115 Bonn, Germany.
Bartholomy
O
O
Anisovich
A V
AV
Anton
G
G
Bantes
R
R
Beloglazov
Yu
Y
Bogendörfer
R
R
Castelijns
R
R
Ehmanns
A
A
Ernst
J
J
Fabry
I
I
Flemming
H
H
Fösel
A
A
Freiesleben
H
H
Fuchs
M
M
Funke
Ch
Ch
Gothe
R
R
Gridnev
A
A
Gutz
E
E
Höffgen
S K
SK
Horn
I
I
Hössl
J
J
Joosten
R
R
Junkersfeld
J
J
Kalinowsky
H
H
Klein
F
F
Klempt
E
E
Koch
H
H
Konrad
M
M
Kopf
B
B
Krusche
B
B
Langheinrich
J
J
Löhner
H
H
Lopatin
I
I
Lotz
J
J
Matthäy
H
H
Menze
D
D
Messchendorp
J
J
Morales
C
C
Novinski
D
D
Ostrick
M
M
van Pee
H
H
Radkov
A
A
Reinnarth
J
J
Sarantsev
A V
AV
Schadmand
S
S
Schmidt
Ch
Ch
Schmieden
H
H
Schoch
B
B
Suft
G
G
Sumachev
V
V
Szczepanek
T
T
Thoma
U
U
Walther
D
D
Weinheimer
Ch
Ch