Download or read book Measurement of the B 2!X{sub S} Ll− Branching Fraction Using a Sum Over Exclusive Modes written by and published by . This book was released on 2003 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the branching fraction for the flavor-changing neutral current process B 2!X{sub s}ll− based on a sample of 88.9 x 106 [Upsilon](4S) 2!B{bar B} events recorded with the BABAR detector at the PEP-II ee− storage ring. The final state is reconstructed from pairs of electrons or muons and a hadronic system consisting of one K{sup ±} or K{sub s}° and up to two pions, with at most one [pi]°. Summing over both lepton flavors, we observe a signal of 41 ± 10(stat) ± 2(syst) events with a statistical significance of 4.6 [sigma]. The inclusive branching fraction is determined to be [Beta](B 2!X{sub s}l+l−) = (6.3 {+-} 1.6(stat){sub -1.5}{sup +1.8}(syst)) x 10−6 for m(l+l−)> 0.2 GeV/c2. All results are preliminary.