First Measurement of the Gerasimov-Drell-Hearn Sum Rule for 1H from 0.7 to 1.8 GeV at ELSA.

Authors :: Dutz H
Helbing K
Krimmer J
Speckner T
Zeitler G
Ahrens J
Altieri S
Annand JR
Anton G
Arends HJ
Beck R
Bock A
Bradtke C
Braghieri A
v Drachenfels W
Frommberger F
Godo M
Goertz S
Grabmayr P
Hasegawa S
Hansen K
Harmsen J
Heid E
Hillert W
Holvoet H
Horikawa N
Iwata T
Van Hoorebeke L
d'Hose N
Jennewein P
Kiel B
Klein F
Kondratiev R
Lang M
Lannoy B
Leukel R
Lisin V
Menze D
Meyer W
Michel T
Naumann J
Panzeri A
Pedroni P
Pinelli T
Preobrajenski I
Radtke E
Reicherz G
Rohlof C
Rostomyan T
Sauer M
Schoch B
Schumacher M
Tamas G
Thomas A
van de Vyver R
Weihofen W
Zapadtka F
Source :: Physical review letters [Phys Rev Lett] 2003 Nov 07; Vol. 91 (19), pp. 192001. Date of Electronic Publication: 2003 Nov 04.
Publication Year :: 2003
Abstract: To verify the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the first time experimentally, we measured the helicity dependent total photoabsorption cross section with circularly polarized real photons and longitudinally polarized nucleons in the photon energy range 0.68-1.82 GeV with the tagged photon facility at ELSA. The experiment was carried out with a 4pi detection system, a circularly polarized tagged photon beam, and a frozen spin polarized proton target. The contribution to the GDH sum rule in this photon energy range is [49.9+/-2.4(stat)+/-2.2(syst)] microb.

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