Proton spin structure in the resonance region.
We have examined the spin structure of the proton in the region of the nucleon resonances (1.085 GeV<W<1.910 GeV) at an average four momentum transfer of Q2=1.3 GeV2. Using the Jefferson Lab polarized electron beam, a spectrometer, and a polarized solid target, we measured the asymmetries A|| and A(perpendicular) to high precision, and extracted the asymmetries A1 and A2, and the spin structure functions g1 and g2. We found a notably nonzero A(perpendicular), significant contributions from higher-twist effects, and only weak support for polarized quark-hadron duality.
Wesselmann
F R
FR
University of Virginia, Charlottesville, VA 22903, USA.
Slifer
K
K
Tajima
S
S
Aghalaryan
A
A
Ahmidouch
A
A
Asaturyan
R
R
Bloch
F
F
Boeglin
W
W
Bosted
P
P
Carasco
C
C
Carlini
R
R
Cha
J
J
Chen
J P
JP
Christy
M E
ME
Cole
L
L
Coman
L
L
Crabb
D
D
Danagoulian
S
S
Day
D
D
Dunne
J
J
Elaasar
M
M
Ent
R
R
Fenker
H
H
Frlez
E
E
Gan
L
L
Gaskell
D
D
Gomez
J
J
Hu
B
B
Jones
M K
MK
Jourdan
J
J
Keith
C
C
Keppel
C E
CE
Khandaker
M
M
Klein
A
A
Kramer
L
L
Liang
Y
Y
Lichtenstadt
J
J
Lindgren
R
R
Mack
D
D
McKee
P
P
McNulty
D
D
Meekins
D
D
Mkrtchyan
H
H
Nasseripour
R
R
Niculescu
I
I
Normand
K
K
Norum
B
B
Pocanic
D
D
Prok
Y
Y
Raue
B
B
Reinhold
J
J
Roche
J
J
Rohe
D
D
Rondón
O A
OA
Savvinov
N
N
Sawatzky
B
B
Seely
M
M
Sick
I
I
Smith
C
C
Smith
G
G
Stepanyan
S
S
Tang
L
L
Testa
G
G
Vulcan
W
W
Wang
K
K
Warren
G
G
Wood
S
S
Yan
C
C
Yuan
L
L
Yun
J
J
Zeier
M
M
Zhu
H
H