HEPData Search

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Study on the cross section asymmetry of deuteron photodisintegration induced by low energy polarized γ quanta

Barannik, V.P. ; Gorbenko, V.G. ; Gushchin, V.A. ; et al.

Yad.Fiz. 38 (1983) 1108-1100, 1983.

Inspire Record 1408810 DOI 10.17182/hepdata.17732

Results are presented on measured asymmetry parameter in the cross sections of the deuteron photodesintegration by linearly polarized photon beam in the energy range 40-70 MeV for the proton emission angles of 75 and 90 deg in the c. m. s. The experimental data are compared with the theoretical calculations by Partovi, Arenhovel, as well as with calculations performed within an invariant approach with gauge-invariant amplitudes in the pole approximation. The results of the calculation by Arenhovel and the present calculations satisfactorily agree with the experimental data, while the Partovi theory does not describe the asymmetry parameter measurements for photon energies above 40 MeV

1 data table

Table 1

No description provided.

Angular dependence of the asymmetry of the cross sections for the reactions $^{4}$He($\gamma , p$)T and $^{4}$He($\gamma , n$)$^{3}$He induced by 40-, 60-, and 80-MeV linearly polarized photons

Lyakhno, Yu.P. ; Voloshuchuk, V.I. ; Ganenko, V.B. ; et al.

Phys.Atom.Nucl. 59 (1996) 14-18, 1996.

Inspire Record 1392928 DOI 10.17182/hepdata.17187

None

1 data table

Table 1

THE ASYMMETRY SIGMA HAS BEEN DETERMINED BY THE FORMULA: D(SIG)/D(OMEGA)=D(SIG0)/D(OMEGA)*(1+P*SIGMA*COS(PHI)), WHERE D(SIG0)/D(OMEGA) - CROSS SECTION ON U NPOLARIZED PHOTON BEAM, P - BEAM POLARIZATION, PHI - ASIMUTHAL ANGLE BETWEEN POLARIZATION VECTOR OF BEAM AND THE PLANE OF THE REACTION.

The Q2-dependence of the neutron spin structure function g2(n) at low Q2.

Kramer, K. ; Armstrong, D.S. ; Averett, T.D. ; et al.

Phys.Rev.Lett. 95 (2005) 142002, 2005.

Inspire Record 684137 DOI 10.17182/hepdata.31614

We present the first measurement of the Q^2-dependence of the neutron spin structure function g_2^n at five kinematic points covering 0.57 (GeV/c)^2 <= Q^2 <= 1.34 (GeV/c)^2 at x~0.2. Though the naive quark-parton model predicts g_2=0, non-zero values for g_2 occur in more realistic models of the nucleon which include quark-gluon correlations, finite quark masses or orbital angular momentum. When scattering from a non-interacting quark, $g_2^n$ can be predicted using next-to-leading order fits to world data for g_1^n. Deviations from this prediction provide an opportunity to examine QCD dynamics in nucleon structure. Our results show a positive deviation from this prediction at lower Q^2, indicating that contributions such as quark-gluon interactions may be important. Precision data obtained for g_1^n are consistent with next-to-leading order fits to world data.

1 data table

Table 1

Measured values of G1N ang G2N.

Backward electroproduction of pi0 mesons on protons in the region of nucleon resonances at four momentum transfer squared Q2 = 1.0-GeV2.

The JLab Hall A collaboration Laveissiere, G. ; Degrande, N. ; Jaminion, S. ; et al.

Phys.Rev.C 69 (2004) 045203, 2004.

Inspire Record 625669 DOI 10.17182/hepdata.25226

Exclusive electroproduction of pi0 mesons on protons in the backward hemisphere has been studied at Q**2 = 1.0 GeV**2 by detecting protons in the forward direction in coincidence with scattered electrons from the 4 GeV electron beam in Jefferson Lab's Hall A. The data span the range of the total (gamma* p) center-of-mass energy W from the pion production threshold to W = 2.0 GeV. The differential cross sections sigma_T+epsilon*sigma_L, sigma_TL, and sigma_TT were separated from the azimuthal distribution and are presented together with the MAID and SAID parametrizations.

12 data tables

Table 1

Cross section SIG(T) + EPSILON*SIG(L) for COS(THETA*) = -0.975.

Table 2

Cross section SIG(T) + EPSILON*SIG(L) for COS(THETA*) = -0.925.

Table 3

Cross section SIG(T) + EPSILON*SIG(L) for COS(THETA*) = -0.875.

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The transverse asymmetry A(T') from quasielastic polarized He-3(pol.)(e(pol.),e') process and the neutron magnetic form factor.

Xu, W. ; Dutta, D. ; Xiong, F. ; et al.

Phys.Rev.Lett. 85 (2000) 2900-2904, 2000.

Inspire Record 531416 DOI 10.17182/hepdata.31474

We have measured the transverse asymmetry from inclusive scattering of longitudinally polarized electrons from polarized 3He nuclei at quasi-elastic kinematics in Hall A at Jefferson Lab with high statistical and systematic precision. The neutron magnetic form factor was extracted based on Faddeev calculations with an experimental uncertainty of less than 2 %.

1 data table

Table 1

Ratio of neutron magnetic form-factor to dipole value.

Measurement of the neutral weak form factors of the proton.

The HAPPEX collaboration Aniol, K.A. ; Armstrong, D.S. ; Baylac, M. ; et al.

Phys.Rev.Lett. 82 (1999) 1096-1100, 1999.

Inspire Record 478059 DOI 10.17182/hepdata.31319

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The kinematic point (theta_lab = 12.3 degrees and Q^2=0.48 (GeV/c)^2) is chosen to provide sensitivity, at a level that is of theoretical interest, to the strange electric form factor G_E^s. The result, A=-14.5 +- 2.2 ppm, is consistent with the electroweak Standard Model and no additional contributions from strange quarks. In particular, the measurement implies G_E^s + 0.39G_M^s = 0.023 +- 0.034 (stat) +- 0.022 (syst) +- 0.026 (delta G_E^n), where the last uncertainty arises from the estimated uncertainty in the neutron electric form factor.

1 data table

Table 1

Longitudinally polarized beam. C=L and C=R means left- and right polarization. The second systematic uncertainty arises from the estimated uncertainty inthe neutron electromagnetic from factor.