1,931 research outputs found
Global Fits of the CKM Matrix
We report upon the present status of global fits to Cabibbo-Kobayashi-Maskawa
matrix.Comment: 3 pages, 3 figures invited talk presented at EPS conference, Aachen
July 17-2
Search for the decay B^+ → τ^+ν_τ
We search for the rare leptonic decay B^+ → τ^+ν_τ in a sample of 232 × 10^6 BB̅ pairs collected with the BABAR detector at the SLAC PEP-II B-Factory. Signal events are selected by examining the properties of the B meson recoiling against the semileptonic decay B^- → D^9*0)ℓ^-ν̅_ ℓ. We find no evidence for a signal and set an upper limit on the branching fraction of B(B^+ → τ^+ν_τ)<2.8 × 10^9-4) at the 90% confidence level. We combine this result with a previous, statistically independent BABAR search for B+→τ+ντ to give an upper limit of B(B^+ → τ^+ν_τ)<2.6 × 10^(-4) at the 90% confidence level
The e^+e^- → 3(π^+π^-), 2(π^+π^-π^0) and K^+K^-2(π^+π^-) cross sections at center-of-mass energies from production threshold to 4.5 GeV measured with initial-state radiation
We study the processes e^+e^- → 3(π^+π^-)γ, 2(π^+π^-π^0)γ and K^+K^-2(π^+π^-)γ, with the photon radiated from the initial state. About 20 000, 33 000 and 4000 fully reconstructed events, respectively, have been selected from 232 fb^(-1) of BABAR data. The invariant mass of the hadronic final state defines the effective e^+e^- center-of-mass energy, so that these data can be compared with the corresponding direct e^+e^- measurements. From the 3(π^+π^-), 2(π^+π^-π^0) and K^+K^-2(π^+π^-) mass spectra, the cross sections for the processes e^+e^- → 3(π^+π^-), e^+e^- → 2(π^+π^-π^0) and e^+e^- → K^+K^-2(π^+π^-) are measured for center-of-mass energies from production threshold to 4.5 GeV. The uncertainty in the cross section measurement is typically 6%–15%. We observe a structure at 1.9 GeV in both cross sections and a resonance structure with mass 1645 ± 0.008 GeV/c^2 and width 0.114 ± 0.014 GeV when the ω(782)η final state is extracted. We observe the J/ψ in all these final states and measure the corresponding branching fractions
Branching fraction limits for B^0 decays to η′η, η′π^0 and ηπ^0
We describe searches for decays to two-body charmless final states η′η, η′π^0 and ηπ^0 of B^0 mesons produced in e^+e^- annihilation. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 232 × 10^6 produced BB̅ pairs. The results for branching fractions are, in units of 10^(-6) (upper limits at 90% C.L.): B(B^0 → η′η)=0.2^(+0.7)_(-0.5) ± 0.4(<1.7), B(B^0 → ηπ^0) = 0.6^(+0.5)_(-0.4) ± 0.1(<1.3), and B(B^0 → η′π^0) = 0.8^(+0.8)_(-0.6) ± 0.1(<2.1). The first error quoted is statistical and the second systematic
Measurement of time-dependent CP asymmetries in B^0→D^((*)±)π^∓ and B^0→D^±ρ^∓ decays
We present updated results on time-dependent CP asymmetries in fully reconstructed B^0→D^((*)±)π^∓ and B^0→D^±ρ^∓ decays in approximately 232×10^6 Υ(4S)→BB events collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. From a time-dependent maximum-likelihood fit we obtain for the parameters related to the CP violation angle 2β+γ: a^(Dπ)=-0.010±0.023±0.007, c_(lep)^(Dπ)=-0.033±0.042±0.012, a^(D*π)=-0.040±0.023±0.010, c_(lep)D^(*π)=0.049± 0.042±0.015,a^(Dρ)=-0.024±0.031±0.009, c_(lep)^(Dρ)=-0.098±0.055±0.018, where the first error is statistical and the second is systematic. Using other measurements and theoretical assumptions, we interpret the results in terms of the angles of the Cabibbo-Kobayashi-Maskawa unitarity triangle and find |sin(2β+γ)|>0.64 (0.40) at 68% (90%) confidence level
Measurement of CP observables for the decays B^± → D^0_(CP)K^±
We present a study of the decay B^- → D^0_(CP)K^±
and its charge conjugate, where D^0_CP) is reconstructed
in CP-even, CP-odd, and non-CP flavor eigenstates, based on a sample of 232 x 10^6 Y(4S) → BB decays
collected with the BABAR detector at the PEP-II e^+e^- storage ring. We measure the partial-rate charge
asymmetries A_(CP±) and the ratios R_(CP±) of the B → D^0K decay branching fractions as measured in CP^±
and non-CP D^0 decays: A_(CP±) 0:35 ± 0.13(stat) ± 0.04(syst), A_(CP-)= -0.06 ± 0.13(stat) ±
0.04(syst), R_(CP+) = 0.90 ± 0.12(stat) ± 0.049syst), and R_(CP-) = 0:86 ± 0.10(stat) ± 0.05(syst)
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