Download or read book Measurement of the Absolute Branching Fractions for $D-̂_s\!\rightarrow\!\ell-̂\bar{\nu}_{\ell}$ and Extraction of the Decay Constant $f_{D_s}$ written by and published by . This book was released on 2010 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The absolute branching fractions for the decays D{sub s}− → l−{bar?}{sub l} (l = e,?, or?) are measured using a data sample corresponding to an integrated luminosity of 521 fb−1 collected at center of mass energies near 10.58 GeV with the BABAR detector at the PEP-II ee− collider at SLAC. The number of D{sub s}− mesons is determined by reconstructing the recoiling system DKX? in events of the type e+e−DKXD*{sub s}−, where D*{sub s}− → D{sub s}−? and X represents additional pions from fragmentation. The D{sub s}− → l°{nu}{sub {ell}} events are detected by full or partial reconstruction of the recoiling system DKX?{ell}. The branching fraction measurements are combined to determine the D{sub s}− decay constant f{sub D{sub s}} = (258.6 ± 6.4 ± 7.5) MeV, where the first uncertainty is statistical and the second is systematic.