Search for Invisible Decays of a Dark Photon Produced in e(+)e(-) Collisions at BABAR

We search for single-photon events in 53 fb^-1 of e+e- collision data collected with the BaBar detector at the PEP-II B-factory. We look for events with a single high-energy photon and a large missing momentum and energy, consistent with production of a spin-1 particle A' through the process e+e->gamma A', A'->invisible. Such particles, referred to as "dark photons", are motivated by theories applying a U(1) gauge symmetry to dark matter. We find no evidence for such processes and set 90% confidence level upper limits on the coupling strength of A' to e+e- in the mass range m_A'<=8 GeV. In particular, our limits exclude the values of the A' coupling suggested by the dark-photon interpretation of the muon (g-2) anomaly, as well as a broad range of parameters for the dark-sector models.Comment: 9 pages, 13 figures; v2 is the version published in Physical Review Letter

Study of the K+ K- invariant-mass dependence of CP asymmetry in B+ → K+K-K+ decays

5 pages, 4 postscript figures, contributed to FPCP2013.As a followup to the latest BABAR amplitude analysis of the decay B+ → K+K-K+, we investigate the K+K- invariant-mass dependence of the CP asymmetry and compare it to that obtained by the LHCb collaboration. The results are based on a data sample of approximately 470 × 106BB decays, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the SLAC National Accelerator Laboratory.OEandNSF (USA), NSERC (Canada), CEAandCNRS-IN2P3 (France), BMBF and DFG (Germany), INFN (Italy), FOM (TheNetherlands), NFR (Norway), MES (Russia), MINECO (Spain), STFC (UnitedKingdom); individuals have received support from the Marie Curie EIF (European Union) and the A.P. Sloan Foundation (USA)

Search for a Stable Six-Quark State at BABAR

International audienceRecent investigations have suggested that the six-quark combination uuddss could be a deeply bound state (S) that has eluded detection so far, and a potential dark matter candidate. We report the first search for a stable, doubly strange six-quark state in ϒ→SΛ¯Λ¯ decays based on a sample of 90×106ϒ(2S) and 110×106ϒ(3S) decays collected by the BABAR experiment. No signal is observed, and 90% confidence level limits on the combined ϒ(2S,3S)→SΛ¯Λ¯ branching fraction in the range (1.2–1.4)×10-7 are derived for mS<2.05  GeV. These bounds set stringent limits on the existence of such exotic particles

Measurement of the neutral D meson mixing parameters in a time-dependent amplitude analysis of the D-0 -> pi(+)pi(-)pi(0) decay

See paper for full list of authors - 11 pages, 2 figures, Submitted to Phys. Rev. DInternational audienceWe measure the $D^0 - {\bar{D}}^0$ mixing parameters using a time-dependent amplitude analysis of the decay $D^0\to\pi^+\pi^-\pi^0$. The data were recorded with the BABAR detector at center-of-mass energies at and near the $\Upsilon(4S)$ resonance, and correspond to an integrated luminosity of approximately 468.1 ${\rm fb}^{-1}$. The neutral $D$ meson candidates are selected from $D^{*}(2010)^+\to D^0 \pi_s^+$ decays where the flavor at the production is identified by the charge of the low momentum pion, $\pi_s^+$. The measured mixing parameters are $x = (1.5\pm1.2\pm0.6) \%$ and $y = (0.2\pm0.9\pm0.5) \%$, where the quoted uncertainties are statistical and systematic, respectively

Search for Rare or Forbidden Decays of the D^{0} Meson.

We present a search for nine lepton-number-violating and three lepton-flavor-violating neutral charm decays of the type D^{0}→h^{'-}h^{-}ℓ^{'+}ℓ^{+} and D^{0}→h^{'-}h^{+}ℓ^{'±}ℓ^{∓}, where h and h^{'} represent a K or π meson and ℓ and ℓ^{'} an electron or muon. The analysis is based on 468  fb^{-1} of e^{+}e^{-} annihilation data collected at or close to the ϒ(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the twelve modes, and we establish 90% confidence level upper limits on the branching fractions in the range (1.0-30.6)×10^{-7}. The limits are between 1 and 3 orders of magnitude more stringent than previous measurements

Search for B−→Λ¯pν¯ν with the BaBar experiment

A search for the rare flavor-changing neutral current process B − → Λ ¯ p ν ¯ ν using data from the BABAR experiment has been performed. A total of 424     fb − 1 of e + e − collision data collected at the center-of-mass energy of the Υ ( 4 S ) resonance is used in this study, corresponding to a sample of ( 471 ± 3 ) × 10 6 B ¯ B pairs. Signal B − → Λ ¯ p ν ¯ ν candidates are identified by first fully reconstructing a B + decay in one of many possible exclusive decays to hadronic final states, then examining detector activity that is not associated with this reconstructed B + decay for evidence of a signal B − → Λ ¯ p ν ¯ ν decay. The data yield is found to be consistent with the expected background contribution under a null signal hypothesis, resulting in an upper limit of B ( B − → Λ ¯ p ν ¯ ν ) < 3.0 × 10 − 5 at the 90% confidence level