4,569 research outputs found
Spin structure function g_1 at low x: status and plans
A brief review of measurements and expectations concerning the spin structure
function g_1 of the nucleon at low values of the scaling variable x is given.Comment: 4 pages, 3 figures. Invited talk presented at the ``International
Workshop on the Spin Structure of the Proton and Polarized Collider
Physics'', ECT*, Trento, Italy, July 23-28, 200
Results on the nucleon spin structure
SMC performed an investigation of the spin structure of the nucleon by
measuring deep inelastic scattering of polarised muons off polarised protons
and deuterons. A summary of the results for spin structure functions and sum
rules is given.Comment: 8 pages, LaTeX, Talk given at the Workshop on "Symmetry and Spin -
PRAHA98", Prag, September 1998. Proceedings to be published by Czech. Journ.
Phy
Search for Anomaly at High x in Polarized Deep Inelastic Scattering Data
An idea of possible anomalous contribution of non-perturbative origin to the
nucleon spin was examined by analysing data on spin asymmetries in polarized
deep inelastic scattering of leptons on nucleons. The region of high Bjorken x
was explored. It was shown that experimental data available at present do not
evidence for this effect.Comment: Submitted to Mod.Phys.Lett.
A new approach to calculate the gluon polarization
We derive the Leading-Order master equation to extract the polarized gluon
distribution G(x;Q^2) = x \deltag(x;Q^2) from polarized proton structure
function, g1p(x;Q^2). By using a Laplace-transform technique, we solve the
master equation and derive the polarized gluon distribution inside the proton.
The test of accuracy which are based on our calculations with two different
methods confirms that we achieve to the correct solution for the polarized
gluon distribution. We show that accurate experimental knowledge of g1p(x;Q^2)
in a region of Bjorken x and Q^2, is all that is needed to determine the
polarized gluon distribution in that region. Therefore, to determine the gluon
polarization \deltag /g,we only need to have accurate experimental data on
un-polarized and polarized structure functions (F2p (x;Q^2) and g1p(x;Q^2)).Comment: 12 pages, 5 figure
Non-perturbative structure of the polarized nucleon sea
We investigate the flavour and quark-antiquark structure of the polarized
nucleon by calculating the parton distribution functions of the nucleon sea
using the meson cloud model. We find that the SU(2) flavor symmetry in the
light antiquark sea and quark-antiquark symmetry in the strange quark sea are
broken, {\it i.e.} \Delta\ubar < \Delta \dbar and \Delta s < \Delta \sbar.
The polarization of the strange sea is found to be positive, which is in
contradiction to previous analyses. We predict a much larger quark-antiquark
asymmetry in the polarized strange quark sea than that in the unpolarized
strange quark sea. Our results for both polarized light quark sea and polarized
strange quark sea are consistent with the recent HERMES data.Comment: RevTex, 17 pages plus 8 PS figure
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
Spin dependent structure function g_1 at low x and low Q^2
Theoretical description of the spin dependent structure function g_1(x,Q^2)
in the region of low values of x and Q^2 is presented. It contains the Vector
Meson Dominance contribution and the QCD improved parton model suitably
extended to the low Q^2 domain. Theoretical predictions are compared with the
recent experimental data in the low x, low Q^2 region
Quantum generalized constant coupling model for geometrically frustrated antiferromagnets
A generalized constant coupling approximation for quantum geometrically
frustrated antiferromagnets is presented. Starting from a frustrated unit, we
introduce the interactions with the surrounding units in terms of an internal
effective field which is fixed by a self consistency condition. Results for the
static magnetic susceptibility and specific heat are compared with previous
results in the framework of this same model for the classical limit. The range
of applicability of the model is discussed.Comment: 11 pages, 6 figures, 1 Tables, typeset using RevTeX 4, small
correction in Table
OPE analysis for polarized deep inelastic scattering
We present an explicit OPE analysis for the first moment of up to order
. This result allows to calculate power corrections to the Bjorken and
Ellis--Jaffe sum rules.Comment: 10 pages, minor modifications, revised version for the journa
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