0000000000199785
AUTHOR
M. Benali
Measurement of the Generalized Polarizabilities of the Proton at Intermediate $Q^2$
Background: Generalized polarizabilities (GPs) are important observables to describe the nucleon structure, and measurements of these observables are still scarce. Purpose: This paper presents details of a virtual Compton scattering (VCS) experiment, performed at the A1 setup at the Mainz Microtron by studying the $e p \to e p \gamma$ reaction. The article focuses on selected aspects of the analysis. Method: The experiment extracted the $P_{LL} -P_{TT} / \epsilon$ and $P_{LT}$ structure functions, as well as the electric and magnetic GPs of the proton, at three new values of the four-momentum transfer squared $Q^2$: 0.10, 0.20 and 0.45 GeV$^2$. Results: We emphasize the importance of the ca…
Rosenbluth Separation of the π^{0} Electroproduction Cross Section.
We present deeply virtual $\pi^0$ electroproduction cross-section measurements at $x_B$=0.36 and three different $Q^2$--values ranging from 1.5 to 2 GeV$^2$, obtained from experiment E07-007 that ran in the Hall A at Jefferson Lab. The Rosenbluth technique was used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component, and thus is far from the asymptotic limit predicted by perturbative Quantum Chromodynamics. An indication of a non-zero longitudinal contribution is provided by the interference term $\sigma_{LT}$ also measured. Results are compared with several models based on the leading twist approach of G…
A glimpse of gluons through deeply virtual compton scattering on the proton
The internal structure of nucleons (protons and neutrons) remains one of the greatest outstanding problems in modern nuclear physics. By scattering high-energy electrons off a proton we are able to resolve its fundamental constituents and probe their momenta and positions. Here we investigate the dynamics of quarks and gluons inside nucleons using deeply virtual Compton scattering (DVCS)—a highly virtual photon scatters off the proton, which subsequently radiates a photon. DVCS interferes with the Bethe-Heitler (BH) process, where the photon is emitted by the electron rather than the proton. We report herein the full determination of the BH-DVCS interference by exploiting the distinct energ…
New Insight in the $Q^2$-Dependence of Proton Generalized Polarizabilities
Virtual Compton scattering on the proton has been investigated at three yet unexplored values of the four-momentum transfer $Q^2$: 0.10, 0.20 and 0.45 GeV$^2$, at the Mainz Microtron. Fits performed using either the low-energy theorem or dispersion relations allowed the extraction of the structure functions $P_{LL} -P_{TT} / \epsilon$ and $P_{LT}$, as well as the electric and magnetic generalized polarizabilities $\alpha_{E1}(Q^2)$ and $\beta_{M1}(Q^2)$. These new results show a smooth and rapid fall-off of $\alpha_{E1}(Q^2)$, in contrast to previous measurements at $Q^2$ = 0.33 GeV$^2$, and provide for the first time a precise mapping of $\beta_{M1}(Q^2)$ in the low-$Q^2$ region.
Rosenbluth separation of the $\pi^0$ Electroproduction Cross Section off the Neutron
We report the first longitudinal/transverse separation of the deeply virtual exclusive $\pi^0$ electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions $d\sigma_L/dt$, $d\sigma_T/dt$, $d\sigma_{LT}/dt$ and $d\sigma_{TT}/dt$ are extracted as a function of the momentum transfer to the recoil system at $Q^2$=1.75 GeV$^2$ and $x_B$=0.36. The $ed \to ed\pi^0$ cross sections are found compatible with the small values expected from theoretical models. The $en \to en\pi^0$ cross sections show a dominance from the response to transversely polarized photons, and are in good agreement with calculations based on the transversity GPDs of the nucle…
Deeply virtual compton scattering off the neutron.
The present experiment exploits the interference between the Deeply Virtual Compton Scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D$({\vec e},e'\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ and $x_B$=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to $E_q$, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.
The MORA project
The MORA (Matter's Origin from the RadioActivity of trapped and oriented ions) project aims at measuring with unprecedented precision the D correlation in the nuclear beta decay of trapped and oriented ions. The D correlation offers the possibility to search for new CP-violating interactions, complementary to searches done at the LHC and with Electric Dipole Moments. Technically, MORA uses an innovative in-trap orientation method which combines the high trapping efficiency of a transparent Paul trap with laser orientation techniques. The trapping, detection, and laser setups are under development, for first tests at the Accelerator laboratory, JYFL, in the coming years.
"Table 28" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 36" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 17" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 40" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 39" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 9" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 22" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 31" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 34" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 33" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 6" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 11" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 37" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 29" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 1" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 21" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 25" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 2" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 32" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 5" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 16" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 24" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 23" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 14" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 26" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 20" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 8" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 10" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 13" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 27" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 38" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 35" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 15" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 30" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 19" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 12" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 4" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 3" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 18" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.
"Table 7" of "A glimpse of gluons through deeply virtual compton scattering on the proton"
Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.