Probing for the Charm Content of $B$ and ${\rm Y}$ Mesons

Abstract

A slow $J/\psi$ bump exists in the inclusive $B\to J/\psi +X$ spectrum, while the softness of $J/\psi$ spectrum in ${\rm Y}(1S)\to J/\psi +X$ decay is in strong contrast with expectations from color octet mechanism. We propose {\it intrinsic} charm as the explanation:the former is due to $\bar{B}\to J/\psi D\pi$,with three charm quarks in the final state; the latter is just a small fraction of ${\rm Y}(1S)\to (c\bar{c}{)}_{\mathrm{slow}}+2$"jet" events, where the slow moving $c\bar{c}$ system evolves into $D^{(\ast )}$ pairs. Experimental search for these phenomena at B Factories and the Tevatron is strongly urged, as the implications go beyond QCD.

Comments: 4 pages, REVTEX, 10 eps figures included. Major revision with more discussions on the rescattering background, and a reappraisal of the Upsilon(1S) decay in the presence of intrinsic charm, leading to a change in Title