Transverse beam spin asymmetries in forward-angle elastic electron-proton scattering.
We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely polarized 3 GeV electrons from unpolarized protons at Q2=0.15, 0.25 (GeV/c)2. The results are inconsistent with calculations solely using the elastic nucleon intermediate state and generally agree with calculations with significant inelastic hadronic intermediate state contributions. A(n) provides a direct probe of the imaginary component of the 2gamma exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments.
Armstrong
D S
DS
Department of Physics, College of William and Mary, Williamsburg, Virginia 23187, USA.
Arvieux
J
J
Asaturyan
R
R
Averett
T
T
Bailey
S L
SL
Batigne
G
G
Beck
D H
DH
Beise
E J
EJ
Benesch
J
J
Bimbot
L
L
Birchall
J
J
Biselli
A
A
Bosted
P
P
Boukobza
E
E
Breuer
H
H
Carlini
R
R
Carr
R
R
Chant
N
N
Chao
Y-C
YC
Chattopadhyay
S
S
Clark
R
R
Covrig
S
S
Cowley
A
A
Dale
D
D
Davis
C
C
Falk
W
W
Finn
J M
JM
Forest
T
T
Franklin
G
G
Furget
C
C
Gaskell
D
D
Grames
J
J
Griffioen
K A
KA
Grimm
K
K
Guillon
B
B
Guler
H
H
Hannelius
L
L
Hasty
R
R
Allen
A Hawthorne
AH
Horn
T
T
Johnston
K
K
Jones
M
M
Kammel
P
P
Kazimi
R
R
King
P M
PM
Kolarkar
A
A
Korkmaz
E
E
Korsch
W
W
Kox
S
S
Kuhn
J
J
Lachniet
J
J
Lee
L
L
Lenoble
J
J
Liatard
E
E
Liu
J
J
Loupias
B
B
Lung
A
A
Marchand
D
D
Martin
J W
JW
McFarlane
K W
KW
McKee
D W
DW
McKeown
R D
RD
Merchez
F
F
Mkrtchyan
H
H
Moffit
B
B
Morlet
M
M
Nakagawa
I
I
Nakahara
K
K
Neveling
R
R
Ong
S
S
Page
S
S
Papavassiliou
V
V
Pate
S F
SF
Phillips
S K
SK
Pitt
M L
ML
Poelker
M
M
Porcelli
T A
TA
Quéméner
G
G
Quinn
B
B
Ramsay
W D
WD
Rauf
A W
AW
Real
J-S
JS
Roche
J
J
Roos
P
P
Rutledge
G A
GA
Secrest
J
J
Simicevic
N
N
Smith
G R
GR
Spayde
D T
DT
Stepanyan
S
S
Stutzman
M
M
Sulkosky
V
V
Tadevosyan
V
V
Tieulent
R
R
Van de Wiele
J
J
van Oers
W T H
WT
Voutier
E
E
Vulcan
W
W
Warren
G
G
Wells
S P
SP
Williamson
S E
SE
Wood
S A
SA
Yan
C
C
Yun
J
J
Zeps
V
V