Target and beam-target spin asymmetries in exclusive pion electroproduction for Q2>1 GeV2. II. ep→eπ0p
2017
Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive
π
0
electroproduction reaction
γ
∗
p
→
p
π
0
, expanding an analysis of the
γ
∗
p
→
n
π
+
reaction from the same experiment. The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic ranges covered are
1.1
<
W
<
3
GeV and
1
<
Q
2
<
6
GeV
2
. Results were obtained for about 5700 bins in
W
,
Q
2
,
cos
(
θ
∗
)
, and
ϕ
∗
. The beam-target asymmetries were found to generally be greater than zero, with relatively modest
ϕ
∗
dependence. The target asymmetries exhibit very strong
ϕ
∗
dependence, with a change in sign occurring between results at low
W
and high
W
, in contrast to
π
+
electroproduction. Reasonable agreement is found with phenomenological fits to previous data for
W
<
1.6
GeV, but significant differences are seen at higher
W
. When combined with cross-sectional measurements, as well as
π
+
observables, the present results will provide powerful constraints on nucleon resonance amplitudes at moderate and large values of
Q
2
, for resonances with masses as high as 2.4 GeV.
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