We have measured the neutron spin asymmetry A1n with high precision at three kinematics in the deep inelastic region at Bjorken x=0.33, 0.47, and 0.60, and Q2=2.7, 3.5, and 4.8 (GeV/c)2, respectively. Our results unambiguously show, for the first time, that A1n crosses zero around x=0.47 and becomes significantly positive at x=0.60. Combined with the world proton data, polarized quark distributions were extracted. Our results, in general, agree with relativistic constituent quark models and with perturbative quantum chromodynamics (PQCD) analyses based on the earlier data.
COBISS.SI-ID: 18749479
In this investigation we have performed the first measurements of the p(e,ep)gamma cross sections in the deeply virtual Compton scattering (DVCS) regime and the valence quark region. The Q2 dependence (from 1.5 to 2.3 GeV2) of the helicity-dependent cross section indicates the twist-2 dominance of DVCS, proving that generalized parton distributions (GPDs) are accessible to experiment at moderate Q2. The helicity-independent cross section has also been measured at Q2=2.3 GeV2.
COBISS.SI-ID: 1966948
In this experimental work we have performed a series of new measurements of the parity-violating asymmetry APV in elastic scattering of 3 GeV electrons off hydrogen and 4He targets at small laboratory angles (low Q2). We have obtained the 4He asymmetries and H asymmetries with unprecedented accuracies superior to those from any other laboratory. These results significantly improve constraints on the electric and magnetic strange form factors GEs and GEm.
COBISS.SI-ID: 1968228
In this landmark set of measurements we measured angular distributions of recoil-polarization response functions for neutral pion electroproduction for W=1.23 GeV at Q2=1.0 (GeV/c)2, obtaining 14 separated response functions plus 2 Rosenbluth combinations; of these, 12 have been observed for the first time. Dynamical models do not describe quantities governed by imaginary parts of interference products well, indicating the need for adjusting magnitudes and phases for nonresonant amplitudes.
COBISS.SI-ID: 1855844
In this paper we report on a set of new precise measurements of the H(e,ep)pi0 process at the Delta(1232) resonance at Q2 = 0.127 (GeV/c)2 obtained at the MIT-Bates out-of-plane scattering facility which are particularly sensitive to the transverse electric amplitude (E2) of the N to Delta transition. The new data have been analyzed together with those of earlier measurements to yield precise quadrupole to dipole amplitude ratios: we obtain highly precise values on the Re(E1+/M1+) and Re(S1+/M1+) ratios.
COBISS.SI-ID: 1842788
We have measured the neutron spin asymmetry A1n with high precision at three kinematics in the deep inelastic region at Bjorken x=0.33, 0.47, and 0.60, and Q2=2.7, 3.5, and 4.8 (GeV/c)2, respectively. Our results unambiguously show, for the first time, that A1n crosses zero around x=0.47 and becomes significantly positive at x=0.60. Combined with the world proton data, polarized quark distributions were extracted. Our results, in general, agree with relativistic constituent quark models and with perturbative quantum chromodynamics (PQCD) analyses based on the earlier data.
COBISS.SI-ID: 18749479
In this investigation we have performed the first measurements of the p(e,ep)gamma cross sections in the deeply virtual Compton scattering (DVCS) regime and the valence quark region. The Q2 dependence (from 1.5 to 2.3 GeV2) of the helicity-dependent cross section indicates the twist-2 dominance of DVCS, proving that generalized parton distributions (GPDs) are accessible to experiment at moderate Q2. The helicity-independent cross section has also been measured at Q2=2.3 GeV2.
COBISS.SI-ID: 1966948
In this experimental work we have performed a series of new measurements of the parity-violating asymmetry APV in elastic scattering of 3 GeV electrons off hydrogen and 4He targets at small laboratory angles (low Q2). We have obtained the 4He asymmetries and H asymmetries with unprecedented accuracies superior to those from any other laboratory. These results significantly improve constraints on the electric and magnetic strange form factors GEs and GEm.
COBISS.SI-ID: 1968228
In this landmark set of measurements we measured angular distributions of recoil-polarization response functions for neutral pion electroproduction for W=1.23 GeV at Q2=1.0 (GeV/c)2, obtaining 14 separated response functions plus 2 Rosenbluth combinations; of these, 12 have been observed for the first time. Dynamical models do not describe quantities governed by imaginary parts of interference products well, indicating the need for adjusting magnitudes and phases for nonresonant amplitudes.
COBISS.SI-ID: 1855844
In this paper we report on a set of new precise measurements of the H(e,ep)pi0 process at the Delta(1232) resonance at Q2 = 0.127 (GeV/c)2 obtained at the MIT-Bates out-of-plane scattering facility which are particularly sensitive to the transverse electric amplitude (E2) of the N to Delta transition. The new data have been analyzed together with those of earlier measurements to yield precise quadrupole to dipole amplitude ratios: we obtain highly precise values on the Re(E1+/M1+) and Re(S1+/M1+) ratios.
COBISS.SI-ID: 1842788