Invariant-mass distribution of cc-bar in Upsilon(1S) -> cc-bar + X
Abstract
We calculate the invariant-mass distribution for the cc-bar pair produced in the inclusive Upsilon(1S) decay based on the color-singlet mechanism of the nonrelativistic quantum chromodynamics factorization approach at leading order in the bottom-quark velocity v_b in the meson rest frame. As the short-distance processes, we consider bb-bar -> g^*gg followed by g^* -> cc-bar and bb-bar -> gamma^* -> cc-bar at leading order in the strong coupling. The invariant-mass distribution of the bb-bar -> cc-bar gg contribution has a sharp peak just above the threshold and that of the bb-bar -> gamma^* -> cc-bar channel is concentrated at the maximally allowed kinematic end point. We predict that Gamma[Upsilon(1S) -> cc-bar+X]/Gamma[Upsilon(1S)->light hadrons] = 0.065 alpha_s, which is smaller than a previous result by about 20%.
Keywords
Cite
@article{arxiv.0805.1989,
title = {Invariant-mass distribution of cc-bar in Upsilon(1S) -> cc-bar + X},
author = {Hee Sok Chung and Taewon Kim and Jungil Lee},
journal= {arXiv preprint arXiv:0805.1989},
year = {2009}
}
Comments
15 pages, 1 figure