Related papers: Comment on the recent COMPASS data on the spin str…
COMPASS, a new fixed target experiment at CERN, aimed at the study of nucleon spin structure and hadron spectroscopy, has started to collect physics data in Autumn 2001. This paper describes the COMPASS apparatus and the measurement of the…
We present the results of our final analysis of the full data set of g_1^p(Q^2), the spin structure function of the proton, collected using CLAS at Jefferson Lab in 2000-2001. Polarized electrons with energies of 1.6, 2.5, 4.2 and 5.7 GeV…
The spin structure functions of the proton and the deuteron were measured during the EG4 experiment at Jefferson Lab in 2006. Data were collected for longitudinally polarized electron scattering off longitudinally polarized NH$_3$ and…
The spin dependent structure functions, g$_{1p}$ of the proton and g$_{1n}$ of the neutron, calculated in the nucleon rest frame using a relativistic quark model wave function, are compared with recent experiments.
There have been many versions of spin-dependent parton distributions in the literature. Although most agree with present data within uncertainties, they are based upon different physical assumptions. Some physical models are discussed and…
The present understanding of the spin structure of the nucleon is briefly reviewed. The main focus is on parton helicity distributions, orbital angular momentum of partons as defined through generalized parton distributions, as well as…
The inclusive double-spin asymmetry, A_1^p, has been measured at COMPASS in deepinelastic polarised muon scattering off a large polarised NH3 target. The data, collected in the year 2007, cover the range Q2 > 1 (GeV/c)^2, 0.004 < x < 0.7…
It is shown that the quark-parton model in the standard infinite momentum approach overestimate the proton spin structure function $g_1(x)$ in comparison with the approach taking consistently into account the internal motion of quarks…
Measurements are reported of the proton and deuteron spin structure functions g1 at beam energies of 29.1, 16.2, and 9.7 GeV and g2 at a beam energy of 29.1 GeV. The integrals of g1 over x have been evaluated at fixed Q**2 = 3 (GeV/c)**2…
Spin observables allow a deeper understanding of the nature of the underlying dynamics and positivity reduces substantially their allowed domains. We will present some new positivity constraints for spin observables and their implications…
We propose to analyze CLAS12 RG-C data to study the tensor transverse-momentum-dependent parton distribution functions (TMDs) on deuteron data. The deuteron is the lightest nucleus with spin-1, in essence a weakly bound system of two…
High-energy spin physics became a popular topic recently after the EMC finding for the proton's spin content. There exist unmeasured spin-dependent structure functions ($b_1$, $b_2$, $b_3$, and $b_4$) for spin-one hadrons such as the…
The nucleon spin structure has been an active, exciting and intriguing subject of interest for the last three decades. Recent experimental data on nucleon spin structure at low to intermediate momentum transfers provide new information in…
The review of the nucleon spin structure functions problems is presented. The perturbative QCD predictions for the small x behaviour of the nucleon spin structure functions are discussed. The role of the resummation of the ln^2 1/x terms is…
In a recent eprint [1] it is argued that the experimental determinations of the spin-dependent structure function g1 have been done incorrectly and that a reanalysis of those data suggests that the original motivation to argue fora "spin…
We investigate the possibility to draw conclusions on the sign of the spin-dependent gluon distribution, $\Delta G(x, Q^2)$, from existing polarized DIS data. The spin-dependent parton distributions $\Delta u_v, \Delta d_v, \Delta {\bar u},…
We analyze the quark mass dependence of photon gluon fusion in polarized deep inelastic scattering for both the intrinsic and extrinsic gluon distributions of the nucleon. We calculate the effective number of flavors for each of the heavy…
Recent diffractive structure function measurements by the H1 and ZEUS experiments at HERA are reviewed. Various data sets, obtained using systematically different selection and reconstruction methods, are compared. NLO DGLAP QCD fits are…
We present a Next-to-Leading order perturbative QCD analysis of world data on the spin dependent structure functions $g_1^p, g_1^n$, and $g_1^d$, including the new experimental information on the $Q^2$ dependence of $g_1^n$. Careful…
A new combined next to leading order QCD analysis of the polarized inclusive and semi-inclusive deep inelastic lepton-hadron scattering (DIS) data is presented. In contrast to previous combined analyses, the $1/Q^2$ terms (kinematic -…