Determination of the electric and magnetic form-factors of the proton in the timelike region

Bardin, G. ; Burgun, G. ; Calabrese, R. ; et al.
Nucl.Phys.B 411 (1994) 3-32, 1994.
Inspire Record 376134 DOI 10.17182/hepdata.32865

The s dependence of the electromagnetic proton form factors in the time-like region has been determined from the threshold ( s = 4 M p 2 ) up to s = 4.2 GeV 2 . Data were collected in a dedicated experiment performed at the LEAR antiproton ring at CERN, increasing by one order of magnitude the available statistics. Total and differential cross section of the p p → e − e + reaction have been measured. The electric and magnetic form factors are found to have comparable value. The observed form factor shows a clear steep s dependence close to the threshold.

6 data tables

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Measurements of the electric and magnetic form-factors of the neutron from Q**2 = 1.75-GeV/c**2 to 4-GeV/c**2

Lung, A. ; Stuart, L.M. ; Bosted, Peter E. ; et al.
Phys.Rev.Lett. 70 (1993) 718-721, 1993.
Inspire Record 342252 DOI 10.17182/hepdata.19739

Quasielastic e-d cross sections have been measured at forward and backward angles. Rosenbluth separations were done to obtain RL and RT at Q2=1.75, 2.50, 3.25, and 4.00 (GeV/c)2. The neutron form factors GEn and GMn have been extracted using a nonrelativistic model. The sensitivity to deuteron wave function, relativistic corrections, and models of the inelastic background are reported. The results for GMn are consistent with the dipole form, while GEn is consistent with zero. Comparisons are made to theoretical models based on vector meson dominance, perturbative QCD, and QCD sum rules, as well as constituent quarks.

2 data tables

Magnetic form factors.

Electric form factors.


Precise determination of the electromagnetic form-factor of the proton in the timelike region up to s = 4.2-GeV**2

Bardin, G. ; Burgun, G. ; Calabrese, R. ; et al.
Phys.Lett.B 257 (1991) 514-518, 1991.
Inspire Record 314621 DOI 10.17182/hepdata.48504

The s dependence of the proton form factor in the time-like region has been determined up to s =4.2 GeV 2 , assuming the validity of the | G e | = | G m | = | G | hypothesis. Data were taken in a dedicated experiment performed at the LEAR antiproton ring at CERN, increasing by one order of magnitude the available statistics on the proton form factor near threshold in the time-like region. Our result consist of cross section measurements of the p p → e + e − reaction for different beam momenta in the kinematical r 3.6⩽ s ⩽4.2 GeV 2 . The observed s dependence of the form factor close to threshold differs appreciably from the one suggested by previous experiments.

3 data tables

No description provided.

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Results of one-parameter fit. |Ge|=|Gm| assumed.