Speaker
Lara De Nardo
(DESY / TRIUMF)
Description
Precise measurements of the spin structure functions $g_1^^p(x,Q2)$ and
$g_1^n(x,Q2)$ are presented over the kinematic range 0.0041 $\leq x
\leq $ 0.9 and 0.18 GeV$^2$ $\leq Q2 \leq $ 20 GeV$^2$. The data were
collected at the HERMES experiment at DESY, in deep-inelastic scattering
of 27.6 GeV longitudinally polarized positrons off longitudinally
polarized hydrogen and deuterium gas targets internal to the HERA storage
ring.
The results base on a refined analysis and are corrected for radiative and
detector smearing effects using an unfolding algorithm that accounts for
the kinematic migration of events.
The presently most precise determination of the neutron spin structure function g_1^n
is obtained by combining the HERMES deuteron and proton data.
Integrals of g_1^p, g_1^d and g_1^n are calculated over the measured
x range, at Q2=5 GeV^2. Neglecting any possible contribution to the
g_1^d integral from the regionx<= 0.021, a value of 0.330 +-
0.011 (theo.) +- 0.025 (exp.) +- 0.028 (evol.) is obtained for the
flavor-singlet a_0 in a leading twist NNLO analysis
Primary author
Lara De Nardo
(DESY / TRIUMF)
