Physics – High Energy Physics – High Energy Physics - Phenomenology
Scientific paper
1998-04-06
Surveys High Energ.Phys.14:89-107,1999
Physics
High Energy Physics
High Energy Physics - Phenomenology
Lecture at St.Petersburg Winter School on Theoretical Physics, Febr. 23-28, 1998 to be published in Proceedings, 14 pages, LaT
Scientific paper
The review of current experimental situation in the measurements of the first moment $\Gamma_{p,n}$ of spin dependent nucleon structure functions $g_{1;p,n}(x,Q^2)$ is presented. The results of the calculations of twist-4 corrections to $\Gamma_{p,n}$ are discussed and their accuracy is estimated. The part of the proton spin $\Sigma$ carried by $u, d, s$ quarks is calculated in the framework of the QCD sum rules in the external fields. The operators up to dimension 9 are accounted. An important contribution comes from the operator of dimension 3, which in the limit of massless $u, d, s$ quarks is equal to the derivative of QCD topological susceptibility $\chi' (0)$. The comparison with the experimental data on $\Sigma$ gives $\chi'(0)= (2.3 \pm 0.6) \times 10^{-3} GeV^2$. The limits on $\Sigma$ and $\chi'(0)$ are found from selfconsistency of the sum rule, $\Sigma \ga 0.05, \chi' (0) \ga 1.6 \times 10^{-3} GeV^2$. The values of $g_A = 1.37 \pm 0.10$ and $g^8_A = 0.65 \pm 0.15$ are also determined from the corresponding sum rules.
No associations
LandOfFree
Nucleon spin content and axial coupling constants in QCD sum rules approach does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Nucleon spin content and axial coupling constants in QCD sum rules approach, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nucleon spin content and axial coupling constants in QCD sum rules approach will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-619380