Photonic production of P-wave states of B_c mesons

Abstract

Numerical calculations for the production of $P$-wave levels of $B_c$ quarkonium in $\gamma \gamma$ collisions are performed in the leading $O({\alpha }_s^2{\alpha }_{em}^2)$ order of perturbation theory. The total cross-section of $P$-wave state production is about 10 \% of that for the $S$-wave levels. The contribution of fragmentation component ($6+6$ diagrams) is low, and the basic contribution is determined by the recombination mechanism ($8$ Feynman diagrams). The gauge invariant term of the $\bar{b}\to B_c$ fragmentation ($6$ diagrams) quite accurately reproduces the result of the fragmentation model, whereas there is a strong deviation of the $c\to B_c$ fragmentation term from the predictions of the fragmentation model.

Comments: 7 pages, REVTEX file, 6 figures (uuencoded compressed tar-file)