We propose to use the High Momentum Spectrometer of Hall C combined with the Neutral Particle Spectrometer (NPS) to perform high precision measurements of the Deeply Virtual Compton Scattering (DVCS) ...cross section using a beam of positrons. The combination of measurements with oppositely charged incident beams is the only unambiguous way to disentangle the contribution of the DVCS
2
term in the photon electroproduction cross section from its interference with the Bethe-Heitler amplitude. This provides a stronger way to constrain the Generalized Parton Distributions of the nucleon. A wide range of kinematics accessible with an 11 GeV beam off an unpolarized proton target will be covered. The
Q
2
-
dependence of each contribution will be measured independently.
The quasifree
photon beam asymmetry,
, has been measured at photon energies,
, from 390 to 610 MeV, corresponding to center of mass energy from 1.271 to 1.424 GeV, for the first time. The data were ...collected in the A2 hall of the MAMI electron beam facility with the Crystal Ball and TAPS calorimeters covering pion center-of-mass angles from 49
to 148
. In this kinematic region, polarization observables are sensitive to contributions from the
and
(1440) resonances. The extracted values of
have been compared to predictions based on partial-wave analyses (PWAs) of the existing pion photoproduction database. Our comparison includes the SAID, MAID and Bonn-Gatchina analyses; while a revised SAID fit, including the new
measurements, has also been performed. In addition, isospin symmetry is examined as a way to predict
photoproduction observables, based on fits to published data in the channels
,
and
.
The quasifree
γ
→
d
→
π
0
n
(
p
)
photon beam asymmetry,
Σ
, has been measured at photon energies,
E
γ
, from 390 to 610 MeV, corresponding to center of mass energy from 1.271 to 1.424 GeV, for the ...first time. The data were collected in the A2 hall of the MAMI electron beam facility with the Crystal Ball and TAPS calorimeters covering pion center-of-mass angles from 49
∘
to 148
∘
. In this kinematic region, polarization observables are sensitive to contributions from the
Δ
(
1232
)
and
N
(1440) resonances. The extracted values of
Σ
have been compared to predictions based on partial-wave analyses (PWAs) of the existing pion photoproduction database. Our comparison includes the SAID, MAID and Bonn–Gatchina analyses; while a revised SAID fit, including the new
Σ
measurements, has also been performed. In addition, isospin symmetry is examined as a way to predict
π
0
n
photoproduction observables, based on fits to published data in the channels
π
0
p
,
π
+
n
and
π
-
p
.
Our main interest in creating a secondary high-quality KL-beam is to investigate hyperon spectroscopy through both formation and production processes. We propose to study two-body reactions induced ...by the KL-beam on the proton target. The experiment should measure both differential cross sections and self-analyzed polarizations of the produced Λ-, Σ-, and Ξ-hyperons using the GlueX detector at the Jefferson Lab Hall D. New data will greatly constrain partial-wave analysis and reduce modeldependent uncertainties in the extraction of strange resonance properties, providing a new benchmark for comparisons with QCD-inspired models and LQCD calculations. The measurements will span c.m. cos θ from −0.95 to 0.95 in c.m. range above W = 1490 MeV and up to 4000 MeV.
Neutral Pion Photoproduction on Neutron Bulychev, S. A.; Kudryavtsev, A. E.; Kulikov, V. V. ...
Physics of atomic nuclei,
12/2017, Letnik:
80, Številka:
9
Journal Article
Recenzirano
The reaction γ
n
→ π
0
n
is investigated both theoretically and experimentally as an important step toward determining the electromagnetic coupling constants of the
N
* and Δ* resonances 1. We ...analyze the data on the collisions of γ quanta with energies between 200 and 800 MeV with a deuterium target collected by the A2 experiment in Mainz, Germany. These complement the data for neutral-pion photoproduction on protons obtained by the same experiment 2.
On the photoproduction reactions γd→πNN Briscoe, William J.; Kudryavtsev, Alexander E.; Strakovsky, Igor I. ...
The European physical journal. A, Hadrons and nuclei,
02/2022, Letnik:
58, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A review of our works providing a theoretical description of incoherent pion photoproduction on the deuteron is presented. The existing
γ
d
→
π
N
N
data are analysed, especially those obtained more ...recently by the CLAS Collaboration at JLab, the A2 Collaboration at MAMI at Mainz, and the PION@MAX-lab Collaboration at Lund. A procedure, which accounts for the final-state interactions (FSI), is applied to extract
γ
n
→
π
N
differential cross sections from the deuteron data. The role of FSI is discussed. We also comment on the results of other works in connection with some discrepancies seen in comparing the model with experiment. The electromagnetic properties of baryon
N
∗
resonances, improved using the extracted
γ
n
→
π
N
differential cross sections are presented. A model description of the cross section data from charged-pion photoproduction reactions
γ
d
→
π
±
N
N
near threshold is also given. The
γ
d
→
π
-
p
p
data are used to extract the
E
0
+
multipole and total cross section of the reaction
γ
n
→
π
-
p
near threshold.
New data on pion-photoproduction off the proton have been included in the partial wave analyses Bonn-Gatchina and SAID and in the dynamical coupled-channel approach Julich-Bonn. All reproduce the ...recent new data well: the double polarization data for E, G, H, P and T in $\gamma p \to \pi^0 p$ from ELSA, the beam asymmetry $\Sigma$ for $\gamma p \to \pi^0 p$ and $\pi^+ n$ from Jefferson Laboratory, and the precise new differential cross section and beam asymmetry data $\Sigma$ for $\gamma p \to \pi^0 p$ from MAMI. The new fit results for the multipoles are compared with predictions not taking into account the new data. Lastly, the mutual agreement is improved considerably but still far from being perfect.
.
New data on pion-photoproduction off the proton have been included in the partial-wave analyses Bonn-Gatchina and SAID and in the dynamical coupled-channel approach Jülich-Bonn. All reproduce the ...recent new data well: the double-polarization data for
E
,
G
,
H
,
P
and
T
in
from ELSA, the beam asymmetry
for
and
from Jefferson Laboratory, and the precise new differential cross section and beam asymmetry data
for
from MAMI. The new fit results for the multipoles are compared with predictions not taking into account the new data. The mutual agreement is improved considerably but still far from being perfect.
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