34 research outputs found
Named Models in Coalgebraic Hybrid Logic
Hybrid logic extends modal logic with support for reasoning about individual
states, designated by so-called nominals. We study hybrid logic in the broad
context of coalgebraic semantics, where Kripke frames are replaced with
coalgebras for a given functor, thus covering a wide range of reasoning
principles including, e.g., probabilistic, graded, default, or coalitional
operators. Specifically, we establish generic criteria for a given coalgebraic
hybrid logic to admit named canonical models, with ensuing completeness proofs
for pure extensions on the one hand, and for an extended hybrid language with
local binding on the other. We instantiate our framework with a number of
examples. Notably, we prove completeness of graded hybrid logic with local
binding
Angular distributions in the decay B -> K*l(+)l(-)
We use a sample of 384 million BBbar events collected with the Babar detector at the PEP-II e+e- collider to study angular distributions in the rare decays B -> K* l+l-, where l+l- is either e+e- or mu+mu-. For low dilepton invariant masses, m(l+l-)3.2$ GeV/c^2, we measure AFB=0.76 (+0.52,-0.32) +/- 0.07 FL=0.71 (+0.20,-0.22) +/- 0.04.We are grateful for the excellent luminosity and machine
conditions provided by our PEP-II colleagues, and
for the substantial dedicated effort from the computing
organizations that support BABAR. The collaborating
institutions wish to thank SLAC for its support and
kind hospitality. This work is supported by DOE and
NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3
(France), BMBF and DFG (Germany), INFN (Italy),
FOM (The Netherlands), NFR (Norway), MES (Russia),
MEC (Spain), and STFC (United Kingdom). Individuals
have received support from the Marie Curie EIF (European
Union) and the A. P. Sloan Foundation.Peer reviewe
Search for decays of B-0 -> e(+)e(-), B-0 -> mu(+)mu(-), B-0 -> e(+/-)mu(-/+)
We present a search for the decays B-0 -> e(+)e(-), B-0 ->mu(+)mu(-), and B-0 -> e(+/-)mu(-/+) in data collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC B Factory. Using a data set of 111 fb(-1), we find no evidence for a signal in any of the three channels investigated and set the following branching fraction upper limits at the 90% confidence level: B(B-0 -> e(+)e(-))mu(+)mu(-)) e(+/-)mu(-/+))< 18x10(-8)
Evidence for B+ --> tau+ nu_tau decays using hadronic B tags
10 pages, 7 postscript figures, contributed to 35th International Conference on High Energy Physics, July 22-28, Paris (ICHEP 2010)We present a search for the decay B+ --> tau+ nu_tau using 467.8 x 10^6 B B-bar pairs collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC PEP-II B-Factory. We select a sample of events with one completely reconstructed B- in an hadronic decay mode (B- --> D{(*)0}X- and B- --> J/psi X-). We examine the rest of the event to search for a B+ --> tau+ nu_tau decay. We identify the tau+ lepton in the following modes: tau+ --> e+ nu nu, tau+ --> mu+ nu nu, tau+ --> pi+ nu and tau+ --> rho nu. We find an excess of events with respect to expected background, which excludes the null signal hypothesis at the level of 3.3 sigma and can be converted to a branching fraction central value of B( B+ --> tau+ nu_tau )=( 1.80 +0.57 -0.54 (stat.) +-0.26 (syst.)) x 10^{-4}
Search for the B+ -> K+vv Decay Using Semi-Leptonic Tags
11 pages, 6 figures, submitted to Phys. Rev. DWe present an update of the search for the flavor-changing neutral current B+ -> K+vv decay using 351 x 10^6 BB pairs collected at the Y(4S) resonance with the BABAR detector at the SLAC PEP-II B factory. Due to the presence of two neutrinos in the final state, we require the reconstruction of the companion B in the event through the decay channel B- -> D0l-v. We find 38 candidates in the data with an expected background of 31 +/- 12. This allows us to set an upper limit on the branching fraction for B+ -> K+vv of 4.5 x 10^-5 at 90% confidence level
Observation of the semileptonic decays B -> D-*tau(-)(nu)over-bar(tau) and evidence for B -> D tau(-)(nu)over-bar(tau)
We present measurements of the semileptonic decays B--> D-0 tau(-)(nu) over bar (tau), B--> D-*0 tau(-)(nu) over bar (tau), (B) over bar (0)-> D+tau(-)(nu) over bar (tau), and (B) over bar (0)-> D*+tau(-)(nu) over bar (tau), which are potentially sensitive to non-standard model amplitudes. The data sample comprises 232x10(6) Upsilon(4S)-> B (B) over bar decays collected with the BABAR detector. From a combined fit to B- and (B) over bar (0) channels, we obtain the branching fractions B(B -> D tau(-)(nu) over bar (tau))=(0.86 +/- 0.24 +/- 0.11 +/- 0.06)% and B(B -> D-*tau(-)(nu) over bar (tau))=(1.62 +/- 0.31 +/- 0.10 +/- 0.05)% (normalized for the (B) over bar (0)), where the uncertainties are statistical, systematic, and normalization-mode-related
Evidence for Transitions From a Sum of Exclusive Final States in the Hadronic Final State Mass Range
16 pages, 7 postscript figures, contributed to the XXIIIrd International Symposium on Lepton and Photon Interactions at High Energies, 8/13 – 8/18/2007, Daegu, KoreaWe present preliminary results of a search for decays with a hadronic mass 1.0 GeV/$c^
Measurement of the Decay
8 pages, 2 postscript figures, submitted to EPS2007 (2007 Europhysics Conference on High Energy Physics, Manchester, England)Using 226 million events recorded on the resonance with the BABAR detector at the SLAC storage rings PEPII, we reconstruct decays using the decay chain and . From the dependence of their differential rate on , the product of the four-velocities of {} and , and using the description of the form factor by Caprini et al., we obtain the preliminary results , , and . The first errors are statistical and the second ones are systematic. \
B meson decays to charmless meson pairs containing eta or eta' mesons
We present updated measurements of the branching fractions for B-0 meson decays to eta K-0, eta eta, eta phi, eta omega, eta K-'(0), eta(')eta('), eta(')phi, and eta(')omega, and branching fractions and CP-violating charge asymmetries for B+ decays to eta pi(+), eta K+, eta(')pi(+), and eta K-'(+). The data represent the full data set of 467x10(6) BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at the SLAC National Accelerator Laboratory. Besides large signals for the four charged B decay modes and for B-0 ->eta K-'(0), we find evidence for three B-0 decay modes at greater than 3.0 sigma significance. We find B(B-0 ->eta K-0)=(1.15(-0.38)(+0.43)+/- 0.09)x10(-6), B(B-0 ->eta omega)=(0.94(-0.30)(+0.35)+/- 0.09)x10(-6), and B(B-0 ->eta(')omega)=(1.01(-0.38)(+0.46)+/- 0.09)x10(-6), where the first (second) uncertainty is statistical (systematic). For the B+->eta K+ decay mode, we measure the charge asymmetry A(ch)(B+->eta K+)=-0.36 +/- 0.11 +/- 0.03
Observation of the baryonic B-decay B0bar -> Lambda_c^+ antiproton K^- pi^+
7 pages, 3 postscript figures, submitted to PRD RC; BABAR-PUB-09/014, SLAC-PUB-13675We report the observation of the baryonic B-decay B0bar -> Lambda_c^+ antiproton K^- pi^+, excluding contributions from the decay B0bar -> Lambda_c^+ anti-Lambda K^-. Using a data sample of 467*10^6 BBbar pairs collected with the BABAR detector at the PEP-II storage ring at SLAC, the measured branching fraction is (4.33 +/- 0.82_stat +/- 0.33_syst +/- 1.13_Lambda_c^+)*10^-5. In addition we find evidence for the resonant decay B0bar -> Sigma_c(2455)^++ antiproton K^- and determine its branching fraction to be (1.11 +/- 0.30_stat +/- 0.09_syst +/- 0.29_Lambda_c^+)*10^-5. The errors are statistical, systematic, and due to the uncertainty in the Lambda_c^+ branching fraction. For the resonant decay B0bar -> Lambda_c^+ antiproton K^*0 we obtain an upper limit of 2.42*10^-5 at 90% confidence level