We study initial-state radiation events, e + e − → γ ISR π + π − J / ψ , with data collected with the BABAR detector. We observe an accumulation of events near 4.26 GeV / c 2 in the ...invariant-mass spectrum of π + π − J / ψ . Fits to the mass spectrum indicate that a broad resonance with a mass of about 4.26 GeV / c 2 is required to describe the observed structure. The presence of additional narrow resonances cannot be excluded. The fitted width of the broad resonance is 50 to 90 MeV / c 2 , depending on the fit hypothesis.
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We present measurements of the branching fractions for the three-body decays B 0 → D ( * ) ∓ K 0 π ± and their resonant submodes B 0 → D ( * ) ∓ K * ± using a sample of approximately 88 × 10 6 B ¯¯¯ ...B pairs collected by the BABAR detector at the SLAC PEP-II asymmetric energy storage ring. We measure: B ( B 0 → D ∓ K 0 π ± ) = ( 4.9 ± 0.7 stat ± 0.5 syst ) × 10 − 4 , B ( B 0 → D * ∓ K 0 π ± ) = ( 3.0 ± 0.7 stat ± 0.3 syst ) × 10 − 4 , B ( B 0 → D ∓ K * ± ) = ( 4.6 ± 0.6 stat ± 0.5 syst ) × 10 − 4 , B ( B 0 → D * ∓ K * ± ) = ( 3.2 ± 0.6 stat ± 0.3 syst ) × 10 − 4 . From these measurements we determine the fractions of resonant events to be f ( B 0 → D ∓ K * ± ) = 0.63 ± 0.08 stat ± 0.04 syst and f ( B 0 → D * ∓ K * ± ) = 0.72 ± 0.14 stat ± 0.05 syst .
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We report on a measurement of the Cabibbo-Kobayashi-Maskawa C P -violating phase γ through a Dalitz analysis of neutral D decays to K 0 S π − π + in the processes B ∓ → D ( * ) K ∓ , D ∗ → D π 0 , D ...γ . Using a sample of 227 × 10 6 B ¯¯¯ B pairs collected by the BABAR detector, we measure the amplitude ratios r B = 0.12 ± 0.08 ± 0.03 ± 0.04 and r ∗ B = 0.17 ± 0.10 ± 0.03 ± 0.03 , the relative strong phases δ B = ( 104 ± 45 + 17 + 16 − 21 − 24 ) ° and δ ∗ B = ( − 64 ± 41 + 14 − 12 ± 15 ) ° between the amplitudes A ( B − → ¯¯¯ D ( * ) 0 K − ) and A ( B − → D ( * ) 0 K − ) , and γ = ( 70 ± 31 + 12 + 14 − 10 − 11 ) ° . The first error is statistical, the second is the experimental systematic uncertainty, and the third reflects the Dalitz model uncertainty. The results for the strong and weak phases have a twofold ambiguity.
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We present a determination of the Cabibbo-Kobayashi-Maskawa matrix element | V u b | based on the analysis of semileptonic B decays from a sample of 88 × 10 6 Υ ( 4 S ) decays collected with the ...BABAR detector at the SLAC PEP-II e + e − storage ring. Charmless semileptonic B decays are selected using measurements of the electron energy and the invariant mass squared of the electron-neutrino pair. We obtain | V u b | = ( 3.95 ± 0.26 + 0.58 − 0.42 ± 0.25 ) × 10 − 3 , where the errors represent experimental uncertainties, heavy quark parameter uncertainties, and theoretical uncertainties, respectively.
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35.
Production and decay of Ξ0c at BABAR AUBERT, B; BARATE, R; PALANO, A ...
Physical review letters,
09/2005, Volume:
95, Issue:
14
Journal Article
Peer reviewed
Open access
Using 116.1 fb − 1 of data collected by the BABAR detector, we present an analysis of Ξ 0 c production in B decays and from the c ¯ c continuum, with the Ξ 0 c decaying into Ω − K + and Ξ − π + ...final states. We measure the ratio of branching fractions B ( Ξ 0 c → Ω − K + ) / B ( Ξ 0 c → Ξ − π + ) to be 0.294 ± 0.018 ± 0.016 , where the first uncertainty is statistical and the second is systematic. The Ξ 0 c momentum spectrum is measured on and 40 MeV below the Υ ( 4 S ) resonance. From these spectra the branching fraction product B ( B → Ξ 0 c X ) × B ( Ξ 0 c → Ξ − π + ) is measured to be ( 2.11 ± 0.19 ± 0.25 ) × 10 − 4 , and the cross-section product σ ( e + e − → Ξ 0 c X ) × B ( Ξ 0 c → Ξ − π + ) from the continuum is measured to be ( 388 ± 39 ± 41 ) fb at a center-of-mass energy of 10.58 GeV.
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We present updated measurements of the C P -violating parameters S π π and C π π in B 0 → π + π − decays. Using a sample of 227 × 10 6 Υ ( 4 S ) → B ¯¯¯ B decays collected with the BABAR detector at ...the PEP-II asymmetric-energy e + e − collider at SLAC, we observe 467 ± 33 signal decays and measure S π π = − 0.30 ± 0.17 ( stat ) ± 0.03 ( syst ) and C π π = − 0.09 ± 0.15 ( stat ) ± 0.04 ( syst ) .
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We present a measurement of the branching fraction of the decay B0 --> a1(1260)^{+-} pi^{-+} with a1(1260)^{+-} --> pi^{-+} pi^{+-} pi^{+-}. The data sample consists of 218 million B B-bar pairs ...collected at the Y(4S) resonance and recorded by the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC. The analysis is based on unbinned multivariate maximum likelihood fit. The measured branching fraction is: (16.6 +/- 1.9 +/- 1.5) 10^{-6}. The decay mode, observed for the first time, is seen with a significance of 9.2 sigma (systematic uncertainties included).
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We study the two-body decays of B^\pm mesons to K^\pm and a charmonium state, X_{c\bar c}, in a sample of 210.5 fb^{-1} of data from the BaBar experiment. We perform measurements of absolute ...branching fractions BR(B^\pm --> K^\pm X_{c\bar c}) using a missing mass technique, and report several new or improved results. In particular, the upper limit BR(B^\pm --> K^\pm X(3872))<3.2 10^-4 at 90% CL and the inferred lower limit BR(X(3872) --> J/\psi\pi^+\pi^-)>4.2% will help in understanding the nature of the recently discovered X(3872).
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We report the results of a search for T, CP and CPT violation in B0-B0bar mixing using an inclusive dilepton sample collected by the BaBar experiment at the PEP-II B Factory. Using a sample of 232 ...million BBbar pairs, with a simultaneous likelihood fit of the same-sign and opposite-sign dileptons, we measure the T and CP violation parameter |q/p|-1 = (-0.8 +/- 2.7(stat.) +/- 1.9(syst.))e-03, and the CPT and CP parameters Im(z) = (-13.9 +/- 7.3 (stat.) +/- 3.2(syst.))e-03 and DeltaGamma x Re(z) = (-7.1 +/- 3.9(stat.) +/- 2.0(syst.))e-03 ps^{-1}. The statistical correlation between the measurements of Im(z) and DeltaGamma x Re(z) is 76%.
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A search for the non-conservation of lepton flavor in the decay tau -> electron gamma has been performed with 2.07 x 10^8 e+e- -> tau+ tau- events collected by the BABAR detector at the PEP-II ...storage ring at a center-of-mass energy near 10.58 GeV. We find no evidence for a signal and set an upper limit on the branching ratio of BR(tau -> electron gamma) < 1.1 x 10^-7 at 90% confidence level.
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