arXiv subjects

Dimiter B. Stamenov

Publications and source records attributed to Dimiter B. Stamenov.

23 records · Page 2Linked to original sources

arXiv2005

Role of Positivity Constraints in Determining Polarized Parton Densities

We have re-analyzed the world data on inclusive polarized DIS, in both NLO and LO QCD, including the very precise JLab Hall A neutron data, and have studied the role of positivity constraints, and demonstrated their importance, in determining the strange and gluon densities. We have shown that higher twist corrections are essential in the analysis of the present data on the structure function g1. A consistent QCD analysis is achieved, and results for the polarized parton densities are given in both the MSbare and JET schemes.

hep-ph↗

arXiv2001

Polarized Parton Densities in the Nucleon

We present a new NLO QCD analysis of the world data on inclusive polarized deep inelastic scattering. Comparing to our previous analysis: i) the values of g_A and a_8=3F-D are updated ii) the MRST'99 instead of the MRST'98 parametrization for the input unpolarized parton densities is used and iii) the recent SLAC E155 proton data on the spin asymmetry A1 are included in the analysis. A new set of polarized parton densities is extracted from the data and the sensitivity of the results to different positivity constraints is discussed.

hep-ph↗

arXiv2000

On Combining High and Low Q**2 Information on the Polarized Parton Densities

We draw attention to some problems in the combined use of high-Q^2 deep inelastic scattering (DIS) data and low-Q^2 hyperon β-decay data in the determination of the polarized parton densities. We explain why factorization schemes like the JET or AB schemes are the simplest in which to study the implications of the DIS parton densities for the physics of the low-Q^2 region.

hep-ph↗

arXiv1999

A New Study of the Polarized Parton Densities in the Nucleon

We present a new next-to-leading order QCD analysis of the world data on inclusive polarized deep inelastic lepton-nucleon scattering adding to the old set of data the final SMC results, the HERMES proton and very recent SLAC/E155 deuteron data. We find an excellent fit to the data and present results for the polarized parton densities in different factorization schemes. These results are in a good agreement with what follows from the theory. We have also found that the main effect of the newly incorporated data is a better determination of the polarized gluon density.

hep-ph↗

arXiv1995

Constraints on "Fixed Point" QCD from the CCFR Data on Deep Inelastic Neutrino-Nucleon Scattering

The results of LO {\it Fixed point} QCD (FP-QCD) analysis of the CCFR data for the nucleon structure function $~xF_3(x,Q^2)~$ are presented. The predictions of FP-QCD, in which $~α_{s}(Q^2)~$ tends to a nonzero coupling constant $α_{0}$ as $~Q^2\to \infty~,$ are in good agreement with the data. If $~α_{0}~$ is a first order zero of the $~β~$ function, constraints for the possible values of the $~β~$ function parameter $~b~$ regulating how fast $~α_ s(Q^2)~$ tends to its asymptotic value $~α_{0}~$ are found from the data. The corresponding values of $~α_{0}~$ are also determined. Having in mind the recent QCD fits to the same data we conclude that in spite of the high precision and the large $~(x,Q^2)~$ kinematic range of the CCFR data they cannot discriminate between QCD and FP-QCD predictions for $~xF_3(x,Q^2)~$. PACS: 12.38.Qk; 19.90+b; 13.60 Hb

hep-ph↗