Showing papers by "Wouter Verkerke published in 2001"
TL;DR: In this article, the amplitude of the CP-violating asymmetry in neutral B decays to several CP eigenstates was measured using a data sample of 23x10(6) Upsilon(4S)->BbarB decays collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC.
Abstract: We present measurements of time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurement uses a data sample of 23x10(6) Upsilon(4S)-->BbarB decays collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we find events in which one neutral B meson is fully reconstructed in a CP eigenstate containing charmonium and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the standard model is proportional to sin2beta, is derived from the decay time distributions in such events. The result is sin2beta = 0.34+/-0.20 (stat)+/-0.05 (syst).
109 citations
TL;DR: In this paper, the authors measured the cross section of the branching fraction of the mesons in the BABAR detector at energies near the 4S resonance, approximately 10.6 GeV.
Abstract: The production of $J/\psi$ mesons in continuum $e^+e^-$ annihilations has been studied with the BABAR detector at energies near the $\Upsilon(4S)$ resonance, approximately 10.6 GeV. The mesons are distinguished from $J/\psi$ production in B decays through their center-of-mass momentum and energy. We measure the cross section $e^+e^-\to J/\psi X$ to be $2.52\pm 0.21\pm 0.21$ pb; for momentum above 2 GeV/c, it is $1.87\pm 0.10\pm 0.15$ pb. We set a 90% confidence level upper limit on the branching fraction for direct $\Upsilon(4S)$\to J/\psi X$ decays at $4.3\times 10^{-4}$.
47 citations
TL;DR: Measurements of the branching fractions and a search for CP-violating charge asymmetries in charmless hadronic decays of B mesons into two-body final states of kaons and pions show 90% confidence level upper limits for B meson decays to pi(+)pi(0), K+K-, and K0K+ final states.
Abstract: We present measurements of the branching fractions and a search for CP-violating charge asymmetries in charmless hadronic decays of B mesons into two-body final states of kaons and pions. The results are based on a data sample of approximately 23 million BB(bar) pairs collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. We find the following branching fractions: BF(B0-->pi+pi-)= (4.1+/-1.0+/-0.7) x 10^{-6}, BF(B0-->K+pi-)=(16.7+/-1.6+/-1.3) x 10^{-6}, BF(B+-->K+pi0)=(10.8^{+2.1}_{-1.9}+/-1.0) x 10^{-6}, BF(B+-->K0pi+)=(18.2^{+3.3}_{-3.0}+/-2.0) x 10^{-6}, BF(B0-->K0pi0)=(8.2^{+3.1}_{-2.7}+/-1.2) x 10^{-6}. We also report the 90% confidence level upper limits BF(B0-->K+K-) pi+pi0) anti-K0K+) < 2.4 x 10^{-6}. In addition, charge asymmetries have been measured and found to be consistent with zero, where the statistical precision is in the range of +/-0.10 to +/-0.18, depending on the decay mode.
46 citations
TL;DR: In this article, the decay amplitudes in B+J/psi K^*(892) channels were measured using 20.7 fb-1 of data collected at the Upsilon(4S) resonance with the BABAR detector at PEP-II.
Abstract: We present a measurement of the decay amplitudes in B-->J/psi K^*(892) channels using 20.7 fb-1 of data collected at the Upsilon(4S) resonance with the BABAR detector at PEP-II. We measure a P-wave fraction R_perp = (16.0+/-3.2+/-1.4)% and a longitudinal polarization fraction (59.7+/-2.8+/-2.4)%. The measurement of a relative phase that is neither 0 nor pi, phi_ll = 2.50+/-0.20+/-0.08 radians, favors a departure from the factorization hypothesis. Although the decay B-->J/psi Kpi proceeds mainly via K^*(892), there is also evidence for K^*_2(1430) and Kpi S-wave contributions.
40 citations
TL;DR: The results of searches for B decays to charmless two-body final states containing eta(') or omega mesons, based on 20.7 fb(-1) of data collected with the BABAR detector are presented.
Abstract: We present the results of searches for B decays to charmless two-body final states containing $\eta^\prime$ or $\omega$ mesons, based on 20.7 fb$^{-1}$ of data collected with the BABAR detector. We find the branching fractions ${\cal B}(B^+\to\eta^\prime K^+) = (70\pm 8\pm 5)\times 10^{-6}$, ${\cal B}(B^0\to\eta^\prime K^0) = (42^{+13}_{-11}\pm 4)\times 10^{-6}$, and ${\cal B}(B^+\to\omega\pi^+)=6.6^{+2.1}_{-1.8}\pm 0.7)\times 10^{-6}$ where the first error quoted is statistical and the second systematic. We give measurements of four additional modes for which the 90% confidence level upper limits are ${\cal B}(B^0\to\omega K^0) < 13\times 10^{-6}$, ${\cal B}(B^+\to\eta^\prime \pi^+) < 12\times 10^{-6}$, ${\cal B}(B^+\to \omega K^+) < 4\times 10^{-6}$, and ${\cal B}(B^0\to\omega\pi^0) < 3\times 10^{-6}$.
38 citations
TL;DR: The B(0) and B(+) meson lifetimes have been measured in e(+)e(-) annihilation data collected in 1999 and 2000 with the BABAR detector at center-of-mass energies near the Upsilon(4S) resonance.
Abstract: The B0 and B+ meson lifetimes have been measured in e+e- annihilation data collected in 1999 and 2000 with the BABAR detector at center-of-mass energies near the Upsilon(4S) resonance. Events are selected in which one B meson is fully reconstructed in a hadronic final state while the second B meson is reconstructed inclusively. A combined fit to the B0 and the B+ decay time difference distributions yields tau_{B0} = 1.546 +/- 0.032 (stat) +/- 0.022(syst) ps, tau_{B+} = 1.673 +/- 0.032 (stat) +/- 0.023 (syst) ps and tau_{B+} / tau_{B0} = 1.082 +/- 0.026 (stat) +/- 0.012 (syst)
21 citations
TL;DR: In this paper, the decays of B mesons collected with the BABAR detector at the PEP-II collider were observed and the measured branching fractions were B(B+--> phiK+) = (7.7(+1.6)(-1.4)+/- 0.
Abstract: We have observed the decays B--> phiK and phiK(*) in a sample of over 45 million B mesons collected with the BABAR detector at the PEP-II collider. The measured branching fractions are B(B+--> phiK+) = (7.7(+1.6)(-1.4)+/-0.8)x10(-6), B(B0--> phiK0) = (8.1(+3.1)(-2.5)+/-0.8)x10(-6), B(B+--> phiK(*+)) = (9.7(+4.2)(-3.4)+/-1.7)x10(-6), and B(B0--> phiK(*0)) = (8.7(+2.5)(-2.1)+/-1.1)x10(-6). We also report the upper limit B(B+--> phipi(+))<1.4x10(-6) ( 90% C.L.).
20 citations
04 Nov 2001
TL;DR: The silicon-vertex tracker (SVT) for the BaBar Experiment at the PEP-H Asymmetric B Factory at Stanford Linear Accelerator Center (SLAC) is a five-layer double-sided ac-coupled silicon-microstrip detector.
Abstract: The silicon-vertex tracker (SVT) for the BaBar Experiment at the PEP-H Asymmetric B Factory at Stanford Linear Accelerator Center (SLAC), is a five-layer double-sided ac-coupled silicon-microstrip detector. It is a crucial element for the precise measurement of the decay position of B mesons, satisfying the severe constraints imposed by the accelerator design, in terms of geometry of the interaction region and conditions of operation. In the following paper, the SVT performance is described. Radiation issues are discussed and the results of different tests aimed to study the decrease in the SVT performance due to radiation damage are presented. The alignment procedure is described, and a few BaBar physics results are presented as examples of the SVT capabilities to reconstruct decay vertices with good resolution and efficiency.
15 citations
TL;DR: In this article, the authors measured the branching fractions of the psi(2S) meson to the leptonic final states e+e- and mu+mu- relative to that for J/psi pi+pi-.
Abstract: We measure the branching fractions of the psi(2S) meson to the leptonic final states e+e- and mu+mu- relative to that for psi(2S)-->J/psi pi+pi-. The method uses psi(2S) mesons produced in the decay of B mesons at the Upsilon(4S) resonance in a data sample collected with the BABAR detector at the Stanford Linear Accelerator Center. Using previous measurements for the psi(2S)-->J/psi pi+pi- branching fraction, we determine the e+e- and mu+mu- branching fractions to be 0.0078+/-0.0009+/-0.0008 and 0.0067+/-0.0008+/-0.0007 respectively.
4 citations
University of Ferrara1, Lawrence Berkeley National Laboratory2, University of Maryland, College Park3, University of Milan4, University of Pavia5, University of Bergamo6, University of Pisa7, Stanford University8, University of Turin9, University of Trieste10, University of California, San Diego11, University of California, Santa Barbara12, University of California, Santa Cruz13, University of Wisconsin-Madison14
01 Nov 2001-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The BaBar Silicon Vertex Tracker (SVT) as mentioned in this paper has achieved its primary design goal, measuring the z vertex coordinate with sufficient accuracy as to allow the measurement of the time-dependent CP asymmetry in the neutral B-meson system.
Abstract: Within its first year of operation, the BaBar Silicon Vertex Tracker (SVT) has accomplished its primary design goal, measuring the z vertex coordinate with sufficient accuracy as to allow the measurement of the time-dependent CP asymmetry in the neutral B-meson system. The SVT consists of five layers of double-sided, AC-coupled silicon-strip detectors of 300 μm thickness with a readout strip pitch of 50–210 μm and a stereo angle of 90° between the strips on the two sides. Detector alignment and performance with respect to spatial resolution and efficiency in the reconstruction of single hits are discussed. In the day-to-day operation of the SVT, radiation damage and protection issues were of primary concern. The SVT is equipped with a dedicated system (SVTRAD) for radiation monitoring and protection, using reverse-biased photodiodes. The evolution of the SVTRAD thresholds on the tolerated radiation level is described. Results on the first-year radiation exposure as measured with the SVTRAD system and on the so far accumulated damage are presented. The implications of test-irradiation results and possible future PEP-II luminosity upgrades on the radiation limited lifetime of the SVT are discussed.
2 citations