0000000000582313
AUTHOR
B Collaboration
Measurement of Semileptonic B Decays into Orbitally Excited Charmed Mesons
We present a study of B decays into semileptonic final states containing charged and neutral D-1(2420) and D-2*(2460). The analysis is based on a data sample of 208 fb(-1) collected at the Y(4S) resonance with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. With a simultaneous fit to four different decay chains, the semileptonic branching fractions are extracted from measurements of the mass difference Delta m = m(D**) - m(D) distribution. Product branching fractions are determined to be B(B+ -> D(1)(0)l(+)nu(l)) x B(D-1(0) -> D*+pi(-)) = (2.97 +/- 0.17 +/- 0.17) x 10(-3), B(B+ -> D-2*l(+)nu(e)) x B(D-2*(0) -> D(*)+pi(-)) = (2.29 +/- 0.23 +/- 0.21) x 10(-3), B(B-0 -> D…
Search for a muonic dark force at BaBar
Many models of physics beyond the Standard Model predict the existence of new Abelian forces with new gauge bosons mediating interactions between "dark sectors" and the Standard Model. We report a search for a dark boson Z' coupling only to the second and third generations of leptons in the reaction e+e- -> mu+mu- Z', Z' -> mu+mu- using 514 fb-1 of data collected by the BABAR experiment. No significant signal is observed for Z' masses in the range 0.212 - 10 GeV. Limits on the coupling parameter g' as low as 7x10^-4 are derived, leading to improvements in the bounds compared to those previously derived from neutrino experiments.