Download or read book Measurement of B --] Xsl+l- Branching Fraction with a Sum Over Exclusive Modes written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We measure the branching fraction for the flavor-changing neutral-current process B [yields] X[sub s][ell][sup +][ell][sup -] with a sample of 89 x 10[sup 6] [Upsilon](4S) [yields] B[bar B] events recorded with the BABAR detector at the PEP-II e[sup +]e[sup -] storage ring. The final state is reconstructed from e[sup +]e[sup -] or [mu][sup +][mu][sup -] pairs and a hadronic system X[sub s] consisting of one K[sup [+-]] or K[sub s][sup 0] and up to two pions, with at most one [pi][sup 0]. We observe a signal of 40 [+-] 10(stat) [+-] 2(syst) events and extract the inclusive branching fraction [Beta] (B [yields] X[sub s][ell][sup +][ell][sup -]) = (5.6 [+-] 1.5(stat) [+-] 0.6(exp syst) [+-] 1.1(model syst)) x 10[sup -6] for m[sub [ell][sup +][ell][sup -]]> 0.2 GeV/c[sup 2].