RESUMEN
A new dark sector antibaryon, denoted ψ_{D}, could be produced in decays of B mesons. This Letter presents a search for B^{+}âψ_{D}+p (and the charge conjugate) decays in e^{+}e^{-} annihilations at 10.58 GeV, using data collected in the BABAR experiment. Data corresponding to an integrated luminosity of 398 fb^{-1} are analyzed. No evidence for a signal is observed. Branching fraction upper limits in the range from 10^{-7}-10^{-5} are obtained at 90% confidence level for masses of 1.0
RESUMEN
We search for the rare flavor-changing neutral current process B^{+}âK^{+}τ^{+}τ^{-} using data from the BABAR experiment. The data sample, collected at the center-of-mass energy of the Ï(4S) resonance, corresponds to a total integrated luminosity of 424 fb^{-1} and to 471×10^{6} BB[over ¯] pairs. We reconstruct one B meson, produced in the Ï(4S)âB^{+}B^{-} decay, in one of many hadronic decay modes and search for activity compatible with a B^{+}âK^{+}τ^{+}τ^{-} decay in the rest of the event. Each τ lepton is required to decay leptonically into an electron or muon and neutrinos. Comparing the expected number of background events with the data sample after applying the selection criteria, we do not find evidence for a signal. The resulting upper limit, at the 90% confidence level, is B(B^{+}âK^{+}τ^{+}τ^{-})<2.25×10^{-3}.
RESUMEN
We measure the mass difference, Δm_{+}, between the D^{*}(2010)^{+} and the D^{+} using the decay chain D^{*}(2010)^{+}âD^{+}π^{0} with D^{+}âK^{-}π^{+}π^{+}. The data were recorded with the BABAR detector at center-of-mass energies at and near the Ï(4S) resonance, and correspond to an integrated luminosity of approximately 468 fb^{-1}. We measure Δm_{+}=(140 601.0±6.8[stat]±12.9[syst]) keV. We combine this result with a previous BABAR measurement of Δm_{0}≡m(D^{*}(2010)^{+})-m(D^{0}) to obtain Δm_{D}=m(D^{+})-m(D^{0})=(4824.9±6.8[stat]±12.9[syst]) keV. These results are compatible with and approximately five times more precise than the Particle Data Group averages.