Cut moments approach in the analysis of DIS data

Abstract

We review the main results on the generalization of the DGLAP evolution equations within the cut Mellin moments (CMM) approach, which allows one to overcome the problem of kinematic constraints in Bjorken x. CMM obtained by multiple integrations as well as multiple differentiations of the original parton distribution also satisfy the DGLAP equations with the simply transformed evolution kernel. The CMM approach provides novel tools to test QCD; here we present one of them. Using appropriate classes of CMM, we construct the generalized Bjorken sum rule that allows us to determine the Bjorken sum rule value from the experimental data in a restricted kinematic range of x. We apply our analysis to COMPASS data on the spin structure function g1.

Dispersion relation analysis of the radiative corrections to gA in the neutron β-decay

“…In the meantime, only the twist-four term among all the HT corrections needs to be included for our precision goal. There are several recent determinations of the coefficient µ p−n 4 [108][109][110] that are largely consistent with each other. In this work we quote the value µ p−n 4 = (−0.047 ± 0.020)M 2 in ref.…”

“…In this work we quote the value µ p−n 4 = (−0.047 ± 0.020)M 2 in ref. [109]. We find that at 2 GeV 2 , the inclusion of the twist-four correction reduces the size of Γ p−n 1,th by about 13%, but its total contribution to d 1 through the integral at Q 2 > 2 GeV 2 is only about 1%.…”

Optimized determination of the polarized Bjorken sum rule in pQCD

“…In this subsection, we compare the results for the BSR obtained here for the optimized PT series for the leading twist contributions with the experimental measurements of COMPASS [18][19][20] (taking into account the results of truncated moments [11,12,21]), the E155 Collaboration at SLAC [22], and JLab EG1-DVCS [23]. These optimized estimates are expectedly higher than the conventional ones.…”

“…Including in the estimates of Eq. (1) also the HT contributions with the values µ p−n 4(kmtk) /M 2 [11] and µ p−n 4(JLab) /M 2 [23], we obtain…”

Nucleon structure functions in the truncated moments approach

“…The ratio parameter r ≡ z 1 /z 2 and x 0 < x min < r < 1. We have tested all methods of estimation of Γ 1 (0) described in [10] and found that a very effective method, universal for the different small-x behavior of g 1 and for x min 0.1, is the first order approximation, Eq. (11).…”