E+ P --> E+ X
[7.253]
Max results
Sort by Reverse order

Showing 2 of 2 results

The Q**2-dependence of the generalised Gerasimov-Drell-Hearn integral for the deuteron, proton and neutron.

The HERMES collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Eur.Phys.J.C 26 (2003) 527-538, 2003.
Inspire Record 600098 DOI 10.17182/hepdata.45286

The Gerasimov-Drell-Hearn (GDH) sum rule connects the anomalous contribution to the magnetic moment of the target nucleus with an energy-weighted integral of the difference of the helicity-dependent photoabsorption cross sections. The data collected by HERMES with a deuterium target are presented together with a re-analysis of previous measurements on the proton. This provides a measurement of the generalised GDH integral covering simultaneously the nucleon-resonance and the deep inelastic scattering regions. The contribution of the nucleon-resonance region is seen to decrease rapidly with increasing $Q^2$. The DIS contribution is sizeable over the full measured range, even down to the lowest measured $Q^2$. As expected, at higher $Q^2$ the data are found to be in agreement with previous measurements of the first moment of $g_1$. From data on the deuteron and proton, the GDH integral for the neutron has been derived and the proton--neutron difference evaluated. This difference is found to satisfy the fundamental Bjorken sum rule at $Q^2 = 5$ GeV$^2$.

6 data tables
Table 1

The value of the GDH integral, as a function of Q**2 , for the deuteron in three W**2 regions, the total ( > 1 GeV**2), the nucleon resonance ( 1 to 4.2 GeV**2) and the DIS (4.2 to 45 GeV**2).

Table 2

The value of the GDH integral, as a function of Q**2 , for the proton in three W**2 regions, the total ( > 1 GeV**2), the nucleon resonance ( 1 to 4.2 GeV**2) and the DIS (4.2 to 45 GeV**2).

Table 3

The value of the GDH integral, as a function of Q**2 , for the neutron in three W**2 regions, the total ( > 1 GeV**2), the nucleon resonance ( 1 to 4.2 GeV**2) and the DIS (4.2 to 45 GeV**2).

More…

Measurement of the proton spin structure function g1(p) with a pure hydrogen target.

The HERMES collaboration Airapetian, A. ; Akopov, N. ; Akushevich, I. ; et al.
Phys.Lett.B 442 (1998) 484-492, 1998.
Inspire Record 473421 DOI 10.17182/hepdata.44220

A measurement of the proton spin structure function g1p(x,Q^2) in deep-inelastic scattering is presented. The data were taken with the 27.6 GeV longitudinally polarised positron beam at HERA incident on a longitudinally polarised pure hydrogen gas target internal to the storage ring. The kinematic range is 0.021<x<0.85 and 0.8 GeV^2<Q^2<20 GeV^2. The integral Int_{0.021}^{0.85} g1p(x)dx evaluated at Q0^2 of 2.5 GeV^2 is 0.122+/-0.003(stat.)+/-0.010(syst.).

2 data tables
Table 1

The second systematic errors listed for G1/F1 (G1) are the uncertainties concerning R (R and F2).

Table 2

G1 evolved at Q2 = 2.5 GeV**2, assuming G1/F1 to be independent of Q2. The second systematic errors listed for are the uncertainties concerning R and F2.