Coward, D.H.
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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.


Measurement of the vector analyzing power in elastic electron proton scattering as a probe of double photon exchange amplitudes.

The SAMPLE collaboration Wells, S.P. ; Averett, T. ; Barkhuff, D. ; et al.
Phys.Rev.C 63 (2001) 064001, 2001.
Inspire Record 524209 DOI 10.17182/hepdata.31444

We report the first measurement of the vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q^2 = 0.1 (GeV/c)^2 and large scattering angles. This quantity should vanish in the single virtual photon exchange, plane wave impulse approximation for this reaction, and can therefore provide information on double photon exchange amplitudes for electromagnetic interactions with hadronic systems. We find a non-zero value of A=-15.4+/-5.4 ppm. No calculations of this observable for nuclei other than spin 0 have been carried out in these kinematics, and the calculation using the spin orbit interaction from a charged point nucleus of spin 0 cannot describe these data.

1 data table
Table 1

Polarized beam.


Parity violation in elastic electron proton scattering and the proton's strange magnetic form-factor.

The SAMPLE collaboration Spayde, D.T. ; Averett, T. ; Barkhuff, D. ; et al.
Phys.Rev.Lett. 84 (2000) 1106-1109, 2000.
Inspire Record 507265 DOI 10.17182/hepdata.31230

We report a new measurement of the parity-violating asymmetry in elastic electron scattering from the proton at backward scattering angles. This asymmetry is sensitive to the strange magnetic form factor of the proton as well as electroweak axial radiative corrections. The new measurement of A=-4.92 +- 0.61 +- 0.73 ppm provides a significant constraint on these quantities. The implications for the strange magnetic form factor are discussed in the context of theoretical estimates for the axial corrections.

1 data table
Table 1

Polarized beam. FORMFACTOR(NAME=GM_S) is the strange quark contribution. FORMFACTOR(NAME=GM_S) is in nucleon magnetic FF.


Measurement of the proton's neutral weak magnetic form factor.

The SAMPLE collaboration Mueller, B. ; Beck, D.H. ; Beise, E.J. ; et al.
Phys.Rev.Lett. 78 (1997) 3824-3827, 1997.
Inspire Record 440739 DOI 10.17182/hepdata.31349

We report the first measurement of the parity-violating asymmetry in elastic electron scattering from the proton. The asymmetry depends on the neutral weak magnetic form factor of the proton which contains new information on the contribution of strange quark-antiquark pairs to the magnetic moment of the proton. We obtain the value $G_M~Z= 0.34 \pm 0.09 \pm 0.04 \pm 0.05$ n.m. at $Q~2=0.1$ (GeV/c)${}~2$.

1 data table
Table 1

Polarized beam. FORMFACTOR(NAME=GZM) = (1/4)*(GM_P-GM_N) - SIN2TW*GM_P - (1/4)*GM_S, whereFORMFACTOR(NAME=GM_S) is the strange quark contribution. FORMFACTOR(NAME=GZM) and FORMFACTOR(NAME=GM_S) are in nucleon magnetic FF.


A COMPARISON OF ELECTRON - PROTON AND POSITRON - PROTON ELASTIC SCATTERING AT FOUR MOMENTUM TRANSFERS UP TO 5.0-GeV/c**2

Mar, J. ; Barish, Barry C. ; Pine, Jerome ; et al.
Phys.Rev.Lett. 21 (1968) 482-484, 1968.
Inspire Record 52726 DOI 10.17182/hepdata.21724

Measurements of the ratio (R) of positron-proton and electron-proton elastic-scattering cross sections have been made, with the square of the four-momentum transfer (q2) equal to 0.20, 0.69, 0.73, 1.54, 2.44, 3.27, 3.79, and 5.00 (GeV/c)2. The measurements, after radiative corrections, are consistent with R=1, with standard errors ranging from ±0.016 to ±0.123. The results give limits for the size of the two-photon effects.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


MEASUREMENT OF THE RATIO OF THE PROTON FORM-FACTORS, G(E) / G(M), AT HIGH MOMENTUM TRANSFERS AND THE QUESTION OF SCALING

Litt, J. ; Buschhorn, G. ; Coward, D.H. ; et al.
Phys.Lett.B 31 (1970) 40-44, 1970.
Inspire Record 54895 DOI 10.17182/hepdata.28767

Electron-proton elastic scattering cross sections have been measured at the Stanford Linear Accelerator Center at four-momentum transfers squared (q 2 ) of 1.0, 1.5, 2.0, 2.5and 3.75 (GeV/ c ) 2 . The angular distributions at q 2 = 2.5 and 3.75 (GeV/ c ) 2 are sufficient to provide values of the ratio G E / G M independent of the results from other laboratories. Our results are compatible with scaling, G E (q 2 ) = G M (q 2 )/ μ , within the experimental errors.

6 data tables
Table 1

No description provided.

Table 2

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Table 3

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Elastic electron - Proton Scattering at Large Four Momentum Transfer

Kirk, Paul N. ; Breidenbach, Martin ; Friedman, Jerome I. ; et al.
Phys.Rev.D 8 (1973) 63-91, 1973.
Inspire Record 73424 DOI 10.17182/hepdata.21999

Electron-proton elastic-scattering cross sections have been measured at the Stanford Linear Accelerator Center for four-momentum transfers squared q 2 from 1.0 to 25.0 (GeVc)2. The electric (GEp) and magnetic (GMp) form factors of the proton were not separated, since angular distributions were not measured at each q 2. However, values for GMp were derived assuming various relations between GEp and GMp. Several theoretical models for the behavior of the proton magnetic form factor at high values of q 2 are compared with the data.

22 data tables
Table 1

No description provided.

Table 2

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Table 3

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