We report a new measurement of Rb = Gamma(Z0->b-bbar) / Gamma(Z0->hadrons) using a double tag technique, where the b hemisphere selection is based on the reconstructed mass of the B hadron decay vertex. The measurement was performed using a sample of 130k hadronic Z0 events, collected with the SLD at the SLC. The method utilizes the 3-D vertexing abilities of the CCD pixel vertex detector and the small stable SLC beams to obtain a high b-tagging efficiency and purity. We obtain Rb=0.2142+/-0.0034(stat.)+/-0.0015(syst.)+/-0.0002(R_c).

10.1103/physrevlett.80.660

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Citations (54)

An Improved Measurement of Mixing-induced CP Violation in the Neutral B Meson System

arXiv (Cornell University) (2002)

Kazuo Abe Y. Chao S. Kobayashi S. Yanaka D. Liventsev

We present an improved measurement of the standard model CP violation parameter sin2phi_1 (also known as sin2beta) based on a sample of 85 times 10^6 B Bbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. One neutral B meson is reconstructed in a J/psi K_S, psi(2S) K_S, chi_{c1} K_S, eta_c K_S, J/psi K^{*0}, or J/psi K_L CP-eigenstate decay channel and the flavor of accompanying B meson is identified from itsdecay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we obtain sin2phi_1 = 0.719 +/- 0.074(stat) +/- 0.035(syst). We also report measurements of CP violation parameters for the related B^0 -> J/psi pi^0 decay mode and the penguin-dominated processes B^0 -> eta' K_S, phi K_S and K^+K^- K_S.

B meson

CP violation

10.48550/arxiv.hep-ex/0207098

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Citations (10)

Production of pi(+), pi(-), K+, K-, p, and (p)over-bar in light (uds), c, and b jets from Z(0) decays

Physical Review D (2004)

K. Abe K. Abe И. Адам H. Akimoto D. Aston

Bar (unit)

Feynman graph

Source

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Measurement of the branching ratios of theZ0into heavy quarks

Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology (2005)

Koya Abe Kenji Abe K. Abe И. Адам H. Akimoto

We measure the hadronic branching ratios of the Z0 boson into heavy quarks: Rb=ΓZ0→bb¯/ΓZ0→hadrons and Rc=ΓZ0→cc¯/ΓZ0→hadrons using a multitag technique. The measurement was performed using about 400 000 hadronic Z0 events recorded in the SLC Large Detector experiment at SLAC between 1996 and 1998. The small and stable SLAC Linear Collider beam spot and the CCD-based vertex detector were used to reconstruct bottom and charm hadron decay vertices with high efficiency and purity, which enables us to measure most efficiencies from data. We obtain, Rb=0.21604±0.00098(stat.)±0.00073(syst.)∓0.00012(Rc) and, Rc=0.1744±0.0031(stat.)±0.0020(syst.)∓0.0006(Rb).1 MoreReceived 18 May 2005DOI:https://doi.org/10.1103/PhysRevD.71.112004©2005 American Physical Society

Electron–positron annihilation

Branching fraction

Branching (polymer chemistry)

10.1103/physrevd.71.112004

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Citations (12)

First Direct Measurement of the Parity-Violating Coupling of theZ0to thesQuark

Physical Review Letters (2000)

Koya Abe Kenji Abe T. Abe I. Adam H. Akimoto

We present the first direct measurement of A(s), the parity-violating coupling of the Z0 boson to the strange quark, using approximately 550 000 e(+)e(-)-->Z0-->hadrons events recorded by the SLC Large Detector with a polarized e(-) beam. We tagged Z0-->s&smacr; events by the absence of B or D hadrons and the presence in each hemisphere of a high momentum K+/- or K(0)(s). Fitting the polar angle distributions of the strangeness-signed thrust axis gave A(s) = 0.895+/-0.066(stat)+/-0.062(syst). The analyzing power and uu+d&dmacr; background were constrained using the data, greatly reducing any model dependence.

Parity (physics)

10.1103/physrevlett.85.5059

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Citations (27)

Measurement of the probability for gluon splitting into b anti-b in Z0 decays

arXiv (Cornell University) (1999)

Kenji Abe P. Jacques H. Hwang T. W. Reeves R. K. Yamamoto

We present a preliminary measurement of the rate of gluon splitting into bottom quarks, g -> b bbar, in hadronic Z0 decays collected by SLD between 1996 and 1998. The analysis was performed by looking for secondary bottom production in 4-jet events of any primary flavour. 4-jet events were identified, and a topological vertex-mass technique was applied to each jet in order to identify b or bbar jets. The upgraded CCD based vertex detector gives very high B-tagging efficiency, especially for B hadrons of the low energies typical of this process. The two most nearly collinear b/bbar jets were tagged as originating from g -> b bbar. We measured the rate of secondary b/bbar production per hadronic event, g_bb, to be (3.07+-0.71(stat.)+-0.66(syst.)) * 10**-3.

Source

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Citations (3)

Determination of |V| using the semileptonic decay →De

Physics Letters B (2002)

K. Abe K. Abe R. Abe K. Abe I. Adachi

KEKB

Branching fraction

Cabibbo–Kobayashi–Maskawa matrix

Electron–positron annihilation

Normalization

10.1016/s0370-2693(01)01476-9

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Citations (37)

Search for charmless two-body baryonic decays ofBmesons

Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields (2002)

K. Abe K. Abe K. Abe I. Adachi Byoung Sup Ahn

We report the results of a search for the rare baryonic decays ${B}^{0}\ensuremath{\rightarrow}p\overline{p},$ $\ensuremath{\Lambda}\overline{\ensuremath{\Lambda}},$ and ${B}^{+}\ensuremath{\rightarrow}p\overline{\ensuremath{\Lambda}}.$ The analysis is based on a data set of $31.7\ifmmode\times\else\texttimes\fi{}{10}^{6}B\overline{B}$ events collected by the Belle detector at the KEKB ${e}^{+}{e}^{\ensuremath{-}}$ collider. No statistically significant signals are found, and we set branching fraction upper limits $\mathcal{B}{(B}^{0}\ensuremath{\rightarrow}p\overline{p})<1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6},$ $\mathcal{B}{(B}^{0}\ensuremath{\rightarrow}\ensuremath{\Lambda}\overline{\ensuremath{\Lambda}})<1.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6},$ and $\mathcal{B}{(B}^{+}\ensuremath{\rightarrow}p\overline{\ensuremath{\Lambda}})<2.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ at the 90% confidence level.

KEKB

Branching fraction

10.1103/physrevd.65.091103

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Citations (29)

Production of [Formula Presented] [Formula Presented] [Formula Presented] [Formula Presented] [Formula Presented] [Formula Presented] and [Formula Presented] in hadronic [Formula Presented] decays

Hiroshima University Acedemic Information Repository (Hiroshima University) (1999)

K. Abe K. Abe И. Адам T. Akagi N. J. Allen

d'Alembert's formula

Liouville's formula

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Citations (54)