On the linearly polarized gluon distributions in the color dipole model

We show that the linearly polarized gluon distributions appear in the color dipole model as we derive the full cross sections of the DIS dijet production and the Drell-Yan dijet ($\gamma^*$ jet correlation) process. Together with the normal Weizs\"acker-Williams gluon distribution, the linearly polarized one will contribute to the DIS dijet production cross section as the coefficient of the $\cos(2 \Delta \phi)$ term in the correlation limit. We also derive the exact results for the cross section of the Drell-Yan dijet process, and find that the linearly polarized dipole gluon distribution which is identical to the normal dipole gluon distribution involves in the cross section. The results obtained in this paper agree with the previous transverse momentum dependent factorization study. We further derive the small-$x$ evolution of these linearly polarized gluon distributions and find that they rise as $x$ gets small at high energy.Comment: 10 pages,v2 with minor revisio

Strong Strand Composition Bias in the Genome of Ehrlichia canis Revealed by Multiple Methods

Genes located on the two replicating strands are found to have two separate base/codon usages in Ehrlichia canis genome. Although strand-specific codon usage is not the first observation, for the first time we have applied multiple methods to the analysis of strand composition bias. By combining multiple methods, comprehensive and interesting results are obtained. Among three types of correspondence analysis (COA), absolute codon usages between genes on the two replicating strands are more distinct than relative synonymous codon usage (RSCU) and base usages are more sensitive than both types of codon usages. PR2-plots show that replication-induced bias is much higher than transcription/translation associated bias in the genome. By using the Z curve method, two common genomic characters, i.e., stronger strand composition bias and lower rearrangement frequency are found to exist in 11 obligate intracellular bacteria with separate base/codon usages. We hope more and more researchers will use the multiple methods to analyze strand composition bias in sequenced microbes, particularly obligate intracellular bacteria