21 research outputs found
Spin dependent structure function at small and small
Theoretical expectations concerning the low and low behaviour of
are summarized and compared with the recent SMC data.Comment: 4 pages, plain LATEX, 1 eps figure; contribution to 3rd UK
Phenomenology Workshop on HERA Physics, St. John's College, Durham, UK,
September 199
Regge description of spin-spin asymmetry in photon diffractive dissociation
We explore the possibility whether the gluon helicity distribution can be extracted from a comparison of experimental data on the
longitudinal spin-spin asymmetry in diffractive deep
inelastic scattering with calculations performed within the framework of
perturbative QCD (pQCD). The data could be obtained at the future HERA collider
in scattering of polarized electrons/positrons off polarized protons. In this
paper we look for such kinematical regions where contributions to from
soft processes (reggeon exchanges) are suppressed to guarantee an applicability
of pQCD. It is shown that for the square of the center-of-mass energy
, the hadronic diffractive mass , the momentum transferred to the proton , and
the longitudinal spin-spin asymmetry due to reggeon
exchanges is less than 10^{-4}. This value is presumably lower than the
asymmetry which can be measured with modern experimental technique. This means
that the pQCD prediction can be reliably compared with data in this kinematical
region.Comment: 44 pages, LaTeX, 12 figure
QCD running coupling effects for the non-singlet structure function at small x
A generalization of the leading-order DGLAP evolution at small x is performed
for the non-singlet structure function by resumming the leading-order DGLAP
anomalous dimension to all orders in the QCD coupling. Explicit expressions are
obtained for the non-singlet structure function of the deep inelastic
scattering, taking into account both the double-logarithmic and the
single-logarithmic contributions, including the running alpha_s effects. It is
shown that when these contributions are included, the asymptotic small-x
behaviour is power-like, with an exponent of about 0.4.Comment: Latex, 20 pages, 7 figure