The charge form factor of the neutron from the reaction H-2(pol.)(e(pol.),e' n)p.

Passchier, I. ; Alarcon, R. ; Bauer, T.S. ; et al.
Phys.Rev.Lett. 82 (1999) 4988-4991, 1999.
Inspire Record 504073 DOI 10.17182/hepdata.31239

We report on the first measurement of spin-correlation parameters in quasifree electron scattering from vector-polarized deuterium. Polarized electrons were injected into an electron storage ring at a beam energy of 720~MeV. A Siberian snake was employed to preserve longitudinal polarization at the interaction point. Vector-polarized deuterium was produced by an atomic beam source and injected into an open-ended cylindrical cell, internal to the electron storage ring. The spin correlation parameter A^V_{ed} was measured for the reaction \pol{2H}(\pol{e},e'n)p at a four-momentum transfer squared of 0.21 (GeV/c)^2 from which a value for the charge form factor of the neutron was extracted.

1 data table

No description provided.


First Measurement of Form Factors of the Decay Xi0->Sigma+ e- anti-nu/e

The KTeV collaboration Alavi-Harati, A. ; Alexopoulos, T. ; Arenton, M. ; et al.
Phys.Rev.Lett. 87 (2001) 132001, 2001.
Inspire Record 556399 DOI 10.17182/hepdata.43756

We present the first measurement of the form factor ratios g1/f1 (direct axial-vector to vector), g2/f1 (second class current) and f2/f1 (weak magnetism) for the decay Xi0 -> Sigma+ e- anti-nu/e using the KTeV (E799) beam line and detector at Fermilab. From the Sigma+ polarization measured with the decay Sigma+ -> p pi0 and the e- - anti-nu/e correlation, we measure g1/f1 to be 1.32 +0.21-0.17(stat.) +/- 0.05(syst.), assuming the SU(3)f (flavor) values for g2/f1 and f2/f1. Our results are all consistent with exact SU(3)f symmetry.

1 data table

Vector(F1) to axial(G1) formfactor ratio. Total systematic error is 0.054.


Measurement of the Sigma- charge radius by Sigma- electron elastic scattering.

The SELEX collaboration Gough Eschrich, Ivo M. ; Kruger, H. ; Simon, J. ; et al.
Phys.Lett.B 522 (2001) 233-239, 2001.
Inspire Record 558329 DOI 10.17182/hepdata.42898

The Sigma^- mean squared charge radius has been measured in the space-like Q^2 range 0.035-0.105 GeV^2/c^2 by elastic scattering of a Sigma^- beam off atomic electrons. The measurement was performed with the SELEX (E781) spectrometer using the Fermilab hyperon beam at a mean energy of 610 GeV/c. We obtain <r^2> = (0.61 +/- 0.12 (stat.) +/- 0.09 (syst.)) fm^2. The proton and pi^- charge radii were measured as well and are consistent with results of other experiments. Our result agrees with the recently measured strong interaction radius of the Sigma^-.

1 data table

Total systematic errors are given.


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

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

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.


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

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


Measurement of the neutron electric form factor G(E,n) in the quasifree H-2(e(pol.),e' n(pol.))p reaction.

Ostrick, M. ; Herberg, C. ; Andresen, H.G. ; et al.
Phys.Rev.Lett. 83 (1999) 276-279, 1999.
Inspire Record 506748 DOI 10.17182/hepdata.19444

The electric form factor of the neutron GE,n has been measured in the quasifree 2H(e→,e′n→)p reaction using the 855 MeV polarized cw electron beam of the Mainz Microtron MAMI. The polarization of the scattered neutrons was analyzed in a polarimeter consisting of two walls of plastic scintillators. The precession of the neutron spin in a magnetic field was used for the first time to circumvent the measurement of the effective analyzing power of the polarimeter and the beam polarization. In this way GE,n could be determined with little model dependence and experimental uncertainties. The result GE,n(0.34GeV2/c2)=0.0611±0.0069stat({+0.0069}{−0.0055})syst is larger than previously assumed.

1 data table

No description provided.


Electroproduction of the Delta Resonance at High Momentum Transfer

Frolov, V.V. ; Adams, G.S. ; Ahmidouch, A. ; et al.
Phys.Rev.Lett. 82 (1999) 45-48, 1999.
Inspire Record 475116 DOI 10.17182/hepdata.41616

We studied the electroproduction of the Delta(1232) resonance via the reaction p(e,e'p)\pi0 at four-momentum transfers Qsq = 2.8 and 4.0 GeV^2. This is the highest Qsq for which exclusive resonance electroproduction has ever been observed. Decay angular distributions for Delta to p-pi0$ were measured over a wide range of barycentric energies covering the resonance. The $N-\Delta$ transition form factor G*_M and ratios of resonant multipoles E{1+}/M{1+} and S{1+}/M{1+} were extracted from the decay angular distributions. These ratios remain small, indicating that perturbative QCD is not applicable for this reaction at these momentum transfers.

4 data tables

CONST(NAME=E1+/M1+) and CONST(NAME=S1+/M1+) are the ratios of the electric quadrupole moment to magnetic dipole moment and Coulomb quadrupole moment to magnetic dipole moment, respectively (see paper). Resonance only.

CONST(NAME=E1+/M1+) and CONST(NAME=S1+/M1+) are the ratios of the electric quadrupole moment to magnetic dipole moment and Coulomb quadrupole moment to magnetic dipole moment, respectively (see paper). Resonance only.

CONST(NAME=E1+/M1+) and CONST(NAME=S1+/M1+) are the ratios of the electric quadrupole moment to magnetic dipole moment and Coulomb quadrupole moment to ma gnetic dipole moment, respectively (see paper). Resonance + background.

More…

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

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.


Electromagnetic proton form-factors at squared four momentum transfers between 1-GeV/c**2 and 3-GeV/c**2

Bartel, W. ; Busser, F.W. ; Dix, W.R. ; et al.
Phys.Lett.B 33 (1970) 245-248, 1970.
Inspire Record 63047 DOI 10.17182/hepdata.45284

Electron-proton elastic scattering cross sections have been measured at four-momentum transfers between 1.0 and 3.0 (GeV/ c ) 2 and at electron scattering angles between 10° and 20° and at about 86° in the laboratory. The proton electromagnetic form factors G E and G M were determined. The results indicate that G E ( q 2 ) decreases faster with increasing q 2 than G M ( q 2 ).

2 data tables

Axis error includes +- 2.5/2.5 contribution (Due to counting statisticss, separation of elastic events, beam monitoring, incident energy, scattering angle, proton absorption, solid angle, target length and density).

CONST(NAME=MU) is the magnetic moment.


Neutron form-factors from quasielastic e d scattering

Bartel, W. ; Buesser, F.W. ; Dix, W.R. ; et al.
Phys.Lett.B 30 (1969) 285-288, 1969.
Inspire Record 56662 DOI 10.17182/hepdata.45282

The reaction e+d→e′+n+p was studied at electron scattering angles θ ⩽ 35° for four-momentum transfers of 0.39, 0.565 and 0.78 (GeV/ c ) 2 . By recording electron-neutron and electron-proton coincidences, the ratio of the electron scattering cross sections on quasi-free neutrons and protons was determined. An estimate of the binding effects, based on a Chew-Low-extrapolation, was made. Values for the neutron form factors were derived.

2 data tables

Axis error includes +- 0.0/0.0 contribution (Due to the different effective solid angles for neutron and proton detection in the counters).

No description provided.


Electroproduction of pions near the $\Delta(1236)$ isobar and the form-factor $G^*_M(q^2)$ of the $({\gamma} N\Delta)$ vertex

Bartel, W. ; Dudelzak, B. ; Krehbiel, H. ; et al.
Phys.Lett.B 28 (1968) 148-151, 1968.
Inspire Record 52791 DOI 10.17182/hepdata.45279

The cross section for inelastic electron-proton scattering was measured at incident electron energies of 1.5 to 6 GeV by magnetic analysis of the scattered electrons at angles between 10° and 35°. For invariant masses of the hardonic final state W ⩽ 1.4 GeV. the measured spectra are compared with theoretical predictions for electroproduction of the Δ(1236) isobar. The magnetic dipole transition form factor G ∗ M ( q 2 ) of the (γ N Δ)-vertex is derived for momentum transfers q 2 = 0.2 − 2.34 (GeV/ c ) 2 ard found to decrease more rapidly with q 2 than the proton form factors.

1 data table

Axis error includes +- 0.0/0.0 contribution.


Electromagnetic form-factors of the proton between 5 and 50 1/fm-squared

Berger, Christoph ; Gersing, E. ; Knop, G. ; et al.
Phys.Lett.B 28 (1968) 276-278, 1968.
Inspire Record 56842 DOI 10.17182/hepdata.29174

The external beam of the 2.5 GeV-electron-synchrotron has been used to measre elastic electron proton scattering at four-momentum-transfers between 15 and 50 fm −2 . By combining these results with measurements at small angles at DESY, we have obtained the electric and magnetic form factors separately. Their ratio shows a deviation from the scaling law.

2 data tables

No description provided.

No description provided.


Quasielastic Electron-Deuteron Scattering Between q$^2$=18f$^{-2}$ and 100f$^{-2}$

Albrecht, W. ; Behrend, H.J. ; Dorner, H. ; et al.
Phys.Lett.B 26 (1968) 642-644, 1968.
Inspire Record 53149 DOI 10.17182/hepdata.29312

Quasielastic e-d scattering measurements were performed up to q 2 = 100 fm −2 . Only the electron was detected. The ratio R= ( d 2 ω d Ω d E′) ed d ω d Ω) ep was measured at the quasielastic peak; the magnetic form factor G M N of the neutron was deduced using the assumption G E N = 0.

2 data tables

No description provided.

CONST(NAME=MU) is the magnetic moment. The magnetic formfarctor (GM) is evaluated ander assumption of GE=0.


A measurement of the electric form-factor of the neutron through d(pol.)(e(pol.),e' n)p at Q**2 = 0.5-(GeV/c)**2.

The E93026 collaboration Zhu, H. ; Ahmidouch, A. ; Anklin, H. ; et al.
Phys.Rev.Lett. 87 (2001) 081801, 2001.
Inspire Record 556212 DOI 10.17182/hepdata.31418

We report the first measurement of the neutron electric form factor $G_E^n$ via $\vec{d}(\vec{e},e'n)p$ using a solid polarized target. $G_E^n$ was determined from the beam-target asymmetry in the scattering of longitudinally polarized electrons from polarized deuterated ammonia, $^{15}$ND$_3$. The measurement was performed in Hall C at Thomas Jefferson National Accelerator Facility (TJNAF) in quasi free kinematics with the target polarization perpendicular to the momentum transfer. The electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle segmented detector. We find $G_E^n = 0.04632\pm0.00616 (stat.) \pm0.00341 (syst.)$ at $Q^2 = 0.495$ (GeV/c)$^2$.

1 data table

No description provided.