-
Kenji Abe,
Koya Abe,
T Abe,
I Adam,
H Akimoto,
D Aston,
K G Baird,
C Baltay,
H R Band,
T L Barklow, [......],
R J Wilson,
W J Wisniewski,
J L Wittlin,
M Woods,
T R Wright,
R K Yamamoto,
J Yashima,
S J Yellin,
C C Young,
H Yuta
[show abstract]
[hide abstract]
ABSTRACT: We present an improved direct measurement of the parity-violation parameter A(b) in the Z boson-b-quark coupling using a self-calibrating track-charge technique applied to a sample enriched in Z-->bb events via the topological reconstruction of the B hadron mass. Manipulation of the Stanford Linear Collider electron-beam polarization permits the measurement of A(b) to be made independently of other Z-pole coupling parameters. From the 1996-1998 sample of 400,000 hadronic Z decays, produced with an average beam polarization of 73.4%, we find A(b)=0.906+/-0.022(stat)+/-0.023(syst).
Physical Review Letters 04/2003; 90(14):141804. · 7.37 Impact Factor
-
Kenji Abe,
Koya Abe,
T. Abe,
I. Adam,
H. Akimoto,
D. Aston,
K. G. Baird,
C. Baltay,
H. R. Band,
T. L. Barklow, [......],
R. J. Wilson,
W. J. Wisniewski,
J. L. Wittlin,
M. Woods,
T. R. Wright,
R. K. Yamamoto,
J. Yashima,
S. J. Yellin,
C. C. Young,
H. Yuta
[show abstract]
[hide abstract]
ABSTRACT: We report a search for Bs0-Bs0̅ oscillations using a sample of 400000 hadronic Z0 decays collected by the SLD experiment. The analysis takes advantage of the electron beam polarization as well as information from the hemisphere opposite that of the reconstructed B decay to tag the B production flavor. The excellent resolution provided by the pixel CCD vertex detector is exploited to cleanly reconstruct both B and cascade D decay vertices, and tag the B decay flavor from the charge difference between them. We exclude the following values of the Bs0-Bs0̅ oscillation frequency: Δms<4.9ps-1 and 7.9<Δms<10.3ps-1 at the 95% confidence level.
Phys. Rev. D. 01/2003; 67(1).
-
Koya Abe,
Kenji Abe,
T. Abe,
I. Adam,
H. Akimoto,
D. Aston,
K. G. Baird,
C. Baltay,
H. R. Band,
T. L. Barklow, [......],
R. J. Wilson,
W. J. Wisniewski,
J. L. Wittlin,
M. Woods,
T. R. Wright,
R. K. Yamamoto,
J. Yashima,
S. J. Yellin,
C. C. Young,
H. Yuta
Physical review D: Particles and fields 09/2002; 66(7):79905.
-
Koya Abe,
Kenji Abe,
T. Abe,
I. Adam,
H. Akimoto,
D. Aston,
K. G. Baird,
C. Baltay,
H. R. Band,
T. L. Barklow, [......],
R. J. Wilson,
W. J. Wisniewski,
J. L. Wittlin,
M. Woods,
T. R. Wright,
R. K. Yamamoto,
J. Yashima,
S. J. Yellin,
C. C. Young,
H. Yuta
[show abstract]
[hide abstract]
ABSTRACT: The structure of 3-jet e+e-→bb̅ g events has been studied using hadronic Z0 decays recorded in the SLC Large Detector experiment at SLAC. Three-jet final states were selected and the charge-coupled-device-based vertex detector was used to identify two of the jets as b or b̅ ; the remaining jet in each event was tagged as the gluon jet. Distributions of the gluon energy and polar angle with respect to the electron beam were measured over the full kinematic range, and used to test the predictions of perturbative QCD. We find that beyond-leading-order QCD calculations are needed to reproduce the features seen in the data. The energy distribution is sensitive to an anomalous b chromomagnetic moment κ at the bb̅ g vertex. We measured κ to be consistent with zero and set 95% confidence level limits on its value, -0.06<κ<0.04.
Phys. Rev. D. 09/2002; 66(5).
-
Kenji Abe,
Koya Abe,
T. Abe,
I. Adam,
H. Akimoto,
D. Aston,
K. G. Baird,
C. Baltay,
H. R. Band,
T. L. Barklow, [......],
R. J. Wilson,
W. J. Wisniewski,
J. L. Wittlin,
M. Woods,
T. R. Wright,
R. K. Yamamoto,
J. Yashima,
S. J. Yellin,
C. C. Young,
H. Yuta
[show abstract]
[hide abstract]
ABSTRACT: A search for Bs0-Bs0̅ oscillations is performed using a sample of 400 000 hadronic Z0 decays collected by the SLAC Large Detector experiment. The Bs0 candidates are reconstructed in the Bs0→Ds-X channel with Ds-→φπ-, K*0K-. The Bs0 production flavor is determined using the large forward-backward asymmetry of polarized Z0→bb̅ decays and charge information in the hemisphere opposite that of the Bs0 candidate. The decay flavor is tagged by the charge of the Ds±. From a sample of 361 candidates with an average Bs0 purity of 40%, we exclude the following values of the oscillation frequency: Δms<1.4ps-1 and 2.4<Δms<5.3ps-1 at the 95% confidence level.
Phys. Rev. D. 08/2002; 66(3).
-
Kenji Abe,
Koya Abe,
T Abe,
I Adam,
H Akimoto,
D Aston,
K G Baird,
C Baltay,
H R Band,
T L Barklow, [......],
R J Wilson,
W J Wisniewski,
J L Wittlin,
M Woods,
T R Wright,
R K Yamamoto,
J Yashima,
S J Yellin,
C C Young,
H Yuta
[show abstract]
[hide abstract]
ABSTRACT: The parity violation parameters A(b) and A(c) of the Zb(b) and Zc(c) couplings have been measured directly, using the polar angle dependence of the polarized cross sections at the Z(0) pole. Bottom and charmed hadrons were tagged via their semileptonic decays. Both the electron and muon analyses take advantage of new multivariate techniques to increase the analyzing power. Based on the 1993-1998 SLD sample of 550,000 Z(0) decays produced with highly polarized electron beams, we measure A(b) = 0.919+/-0.030(stat)+/-0.024(syst), and A(c) = 0.583+/-0.055(stat)+/-0.055(syst).
Physical Review Letters 05/2002; 88(15):151801. · 7.37 Impact Factor
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K Abe,
T Abe,
I Adam,
H Akimoto,
D Aston,
K G Baird,
C Baltay,
H R Band,
T L Barklow,
J M Bauer, [......],
R J Wilson,
W J Wisniewski,
J L Wittlin,
M Woods,
T R Wright,
R K Yamamoto,
J Yashima,
S J Yellin,
C C Young,
H Yuta
[show abstract]
[hide abstract]
ABSTRACT: We have made the first direct symmetry tests in the decays of polarized Z0 bosons into fully identified bbg states, collected in the SLD experiment at SLAC. We searched for evidence of parity violation at the bbg vertex by studying the asymmetries in the b-quark polar- and azimuthal-angle distributions, and for evidence of T-odd, CP-even or CP-odd, final-state interactions by measuring angular correlations between the three-jet plane and the Z0 polarization. We found results consistent with standard model expectations and set 95% C. limits on anomalous contributions.
Physical Review Letters 03/2001; 86(6):962-6. · 7.37 Impact Factor
-
K Abe,
T Abe,
I Adam,
H Akimoto,
D Aston,
K G Baird,
C Baltay,
H R Band,
T L Barklow,
J M Bauer, [......],
R J Wilson,
W J Wisniewski,
J L Wittlin,
M Woods,
T R Wright,
R K Yamamoto,
J Yashima,
S J Yellin,
C C Young,
H Yuta
[show abstract]
[hide abstract]
ABSTRACT: We present final measurements of the Z boson-lepton coupling asymmetry parameters A(e), A(mu), and A(tau) with the complete sample of polarized Z bosons collected by the SLD detector at the SLAC Linear Collider. From the left-right production and decay polar angle asymmetries in leptonic Z decays we measure A(e) = 0.1544+/-0.0060, A(mu) = 0.142+/-0.015, and A(tau) = 0.136+/-0.015. Combined with our left-right asymmetry measured from hadronic decays, we find A(e) = 0.1516+/-0.0021. Assuming lepton universality, we obtain a combined effective weak mixing angle of sin (2)theta(eff)(W) = 0.230 98+/-0.000 26.
Physical Review Letters 03/2001; 86(7):1162-6. · 7.37 Impact Factor
-
Kenji Abe,
Koya Abe,
T. Abe,
I. Adam,
H. Akimoto,
D. Aston,
K. G. Baird,
C. Baltay,
H. R. Band,
T. L. Barklow, [......],
R. J. Wilson,
W. J. Wisniewski,
J. L. Wittlin,
M. Woods,
T. R. Wright,
R. K. Yamamoto,
J. Yashima,
S. J. Yellin,
C. C. Young,
H. Yuta
[show abstract]
[hide abstract]
ABSTRACT: We present a direct measurement of the parity-violation parameter Ac in the coupling of the Z0 to c quarks with the SLD detector. The measurement is based on a sample of 530 k hadronic Z0 decays, produced with a mean electron-beam polarization of |Pe|=73%. The tagging of c-quark events is performed using two methods: the exclusive reconstruction of D*+, D+, and D0 mesons, and the soft pions (πs) produced in the decay of D*+→D0πs+. The large background from D mesons produced in B hadron decays is separated efficiently from the signal using precision vertex information. The combination of these two methods yields Ac=0.688±0.041.
Phys. Rev. D. 01/2001; 63(3).
-
R. Steiner,
H. Yuta,
A.C. Benvenuti,
N. de Groot,
N.J. Allen,
R. Cotton,
P.J. Dervan,
A. Hasan,
A.K. McKemey,
S.J. Watts, [......],
U. Nauenberg,
D.L. Wagner,
B. Williams, P.C. Rowson,
M.H. Shaevitz,
M. Dima,
J.L. Harton,
M.B. Smy,
H. Staengle,
R.J. Wilson
[show abstract]
[hide abstract]
ABSTRACT: The structure of e[sup +]e[sup [minus]][r arrow]b[bar b]g events was studied using Z[sup 0] decays recorded in the SLC Large Detector experiment at SLAC. Three-jet final states were selected and the charge-coupled device-based vertex detector was used to identify two of the jets as [ital b] or [bar b]. Distributions of the gluon energy and polar angle were measured over the full kinematic range for the first time, and compared with perturbative QCD predictions. The energy distribution is potentially sensitive to an anomalous [ital b] chromomagnetic moment [kappa]. We measured [kappa] to be consistent with zero and set the first limits on its value: [minus]0.17[lt][kappa][lt]0.11 at 95[percent] C.L. [copyright] [ital 1999] [ital The American Physical Society]
Physical Review, D. 10/1999; 60:9.
-
Kenji Abe,
Koya Abe,
T. Abe,
I. Adam,
H. Akimoto,
T. Akagi,
N. J. Allen,
W. W. Ash,
D. Aston,
K. G. Baird, [......],
R. K. Yamamoto,
J. M. Yamartino,
X. Yang,
J. Yashima,
S. J. Yellin,
C. C. Young,
H. Yuta,
G. Zapalac,
R. W. Zdarko,
J. Zhou
[show abstract]
[hide abstract]
ABSTRACT: The structure of e+e-→bb̅ g events was studied using Z0 decays recorded in the SLC Large Detector experiment at SLAC. Three-jet final states were selected and the charge-coupled device-based vertex detector was used to identify two of the jets as b or b̅ . Distributions of the gluon energy and polar angle were measured over the full kinematic range for the first time, and compared with perturbative QCD predictions. The energy distribution is potentially sensitive to an anomalous b chromomagnetic moment κ. We measured κ to be consistent with zero and set the first limits on its value: -0.17<κ<0.11 at 95% C.L.
Phys. Rev. D. 10/1999; 60(9).
-
R. Steiner,
H. Yuta,
A.C. Benvenuti,
N.J. Allen,
R. Cotton,
P.J. Dervan,
A. Hasan,
A.K. McKemey,
C. Ward,
S.J. Watts, [......],
U. Nauenberg,
D.L. Wagner,
B. Williams, P.C. Rowson,
M.H. Shaevitz,
M. Dima,
J.L. Harton,
M.B. Smy,
H. Staengle,
R.J. Wilson
[show abstract]
[hide abstract]
ABSTRACT: The parity violation parameters A[sub b] and A[sub c] of the Zb[ovr b] and Zc[ovr c] couplings have been measured directly, using the polar angle dependence of the Z[sup 0] -pole polarized cross sections. Bottom and charmed hadrons were tagged via semileptonic decays. Both the muon and electron identification algorithms take advantage of new multivariate techniques, incorporating for the first time information from the SLD [hacek C]erenkov Ring Imaging Detector. Based on the 1993[endash]1995 SLD sample of 150thinsp000 Z[sup 0] decays produced with highly polarized electron beams, we measure A[sub b]=0.910[plus minus]0.068(stat) [plus minus]0.037(syst) , A[sub c]=0.642[plus minus]0.110(stat) [plus minus]0.063(syst) . [copyright] [ital 1999] [ital The American Physical Society ]
Physical Review Letters 09/1999; 83:17. · 7.37 Impact Factor
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R. Steiner,
H. Yuta,
A.C. Benvenuti,
N.J. Allen,
R. Cotton,
P.J. Dervan,
A. Hasan,
A.K. McKemey,
C. Ward,
S.J. Watts, [......],
U. Nauenberg,
D.L. Wagner,
B. Williams, P.C. Rowson,
M.H. Shaevitz,
M. Dima,
J.L. Harton,
M.B. Smy,
H. Staengle,
R.J. Wilson
[show abstract]
[hide abstract]
ABSTRACT: We present a direct measurement of the parity-violating asymmetry A[sub b] in the Z[sup 0] to b[ovr b] coupling using a new technique to distinguish the b and [ovr b] quarks using charged kaons from B decays. The Z[sup 0] bosons are produced in e[sup +]e[sup [minus]] collisions at the SLC with longitudinally polarized electrons. b[ovr b] events are selected using a secondary vertex mass tag and A[sub b] is determined from the left-right forward-backward asymmetry. From the 1994[endash]1995 data sample, selected from 100thinsp000 hadronic Z[sup 0] decays, we obtain A[sub b]=0.855[plus minus]0.088[sub stat][plus minus] 0.102[sub syst] . [copyright] [ital 1999] [ital The American Physical Society]
Physical Review Letters 08/1999; 83:10. · 7.37 Impact Factor
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K. Abe,
T. Abe,
I. Adam,
T. Akagi,
N. J. Allen,
A. Arodzero,
W. W. Ash,
D. Aston,
K. G. Baird,
C. Baltay, [......],
R. K. Yamamoto,
J. M. Yamartino,
X. Yang,
J. Yashima,
S. J. Yellin,
C. C. Young,
H. Yuta,
G. Zapalac,
R. W. Zdarko,
J. Zhou
[show abstract]
[hide abstract]
ABSTRACT: We have measured the differential production cross sections as a function of scaled momentum xp=2p/Ec.m. of the identified hadron species π+, K+, K0, K*0, φ, p, Λ0, and of the corresponding antihadron species in inclusive hadronic Z0 decays, as well as separately for Z0 decays into light (u, d, s), c and b flavors. Clear flavor dependences are observed, consistent with expectations based upon previously measured production and decay properties of heavy hadrons. These results were used to test the QCD predictions of Gribov and Lipatov, the predictions of QCD in the modified leading logarithm approximation with the ansatz of local parton-hadron duality, and the predictions of three fragmentation models. The ratios of production of different hadron species were also measured as a function of xp and were used to study the suppression of strange meson, strange and non-strange baryon, and vector meson production in the jet fragmentation process. The light-flavor results provide improved tests of the above predictions, as they remove the contribution of heavy hadron production and decay from that of the rest of the fragmentation process. In addition we have compared hadron and antihadron production as a function of xp in light quark (as opposed to antiquark) jets. Differences are observed at high xp, providing direct evidence that higher-momentum hadrons are more likely to contain a primary quark or antiquark. The differences for pseudoscalar and vector kaons provide new measurements of strangeness suppression for high-xp fragmentation products.
Phys. Rev. D. 01/1999; 59(5).
-
R. Steiner,
K. Abe,
H. Yuta,
A.C. Benvenuti,
N.J. Allen,
R. Cotton,
P.J. Dervan,
A. Hasan,
A.K. McKemey,
C. Ward, [......],
M.B. Barakat,
K.G. Baird,
G. Blaylock,
K. Flood,
S.S. Hertzbach,
R.R. Kofler,
M.G. Strauss,
A.I. Trandafir,
J.L. Wittlin,
and others
[show abstract]
[hide abstract]
ABSTRACT: We present an improved comparison of the strong coupling of the gluon to light (q{sub l}=u+d+s), {ital c}, and {ital b} quarks, determined from multijet rates in flavor-tagged samples of hadronic Z{sup 0} decays recorded with the SLC Large Detector at the SLAC Linear Collider between 1993 and 1995. Flavor separation among primary q{sub l}{bar q}{sub l}, c{bar c}, and b{bar b} final states was made on the basis of the reconstructed mass of long-lived heavy-hadron decay vertices, yielding tags with high purity and low bias against {ge} 3-jet final states. We find: {alpha}{sub s}{sup c}/{alpha}{sub s}{sup uds}=1.036{plus_minus}0.043(stat){sub {minus}0.045}{sup +0.041}(syst){sub {minus}0.018}{sup +0.020}(theory) and {alpha}{sub s}{sup b}/{alpha}{sub s}{sup uds}=1.004{plus_minus}0.018(stat){sub {minus}0.031}{sup +0.026}(syst){sub {minus}0.029}{sup +0.018}(theory). {copyright} {ital 1998} {ital The American Physical Society}
Physical Review, D. 12/1998; 59(1).
-
K. Abe,
I. Abt,
T. Akagi,
N. J. Allen,
W. W. Ash,
D. Aston,
K. G. Baird,
C. Baltay,
H. R. Band,
M. B. Barakat, [......],
R. K. Yamamoto,
J. M. Yamartino,
X. Yang,
S. J. Yellin,
C. C. Young,
H. Yuta,
G. Zapalac,
R. W. Zdarko,
C. Zeitlin,
J. Zhou
[show abstract]
[hide abstract]
ABSTRACT: We have measured the distributions of the jet energies in e+e-→qq¯g events, and of the three orientation angles of the event plane, using hadronic Z0 decays collected in the SLD experiment at SLAC. We find that the data are well described by perturbative QCD incorporating vector gluons. We have also studied models of scalar and tensor gluon production and find them to be incompatible with our data.
Phys. Rev. D. 02/1997; 55(5).
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K. Abe,
I. Abt,
C. J. Ahn,
T. Akagi,
N. J. Allen,
W. W. Ash,
D. Aston,
K. G. Baird,
C. Baltay,
H. R. Band, [......],
J. M. Yamartino,
X. Yang,
S. J. Yellin,
C. C. Young,
H. Yuta,
G. Zapalac,
R. W. Zdarko,
C. Zeitlin,
Z. Zhang,
J. Zhou
[show abstract]
[hide abstract]
ABSTRACT: We present measurements of Rb using the SLD at the SLC. The analyses use 2D and 3D impact parameter tags and a displaced 3D vertex tag which all exploit the small size and stability of the e+e- interaction point and the precision 3D CCD pixel vertex detector to achieve high bb¯-tagging efficiencies and purities. The combined measurement yields Rb=0.229±0.011 and is consistent with standard model predictions. © 1996 The American Physical Society.
Phys. Rev. D. 01/1996; 53(3).
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M Swartz,
H R Band,
F.-J. Decker,
P. Emma,
M J Fero,
R Frey,
R King,
A Lath,
T. Limberg,
R Prepost, P C Rowson,
B A Schumm,
M Woods,
M Zolotorev
[show abstract]
[hide abstract]
ABSTRACT: In 1992, L.G. Levchuk noted that the asymmetries measured in M\o ller scattering polarimeters could be significantly affected by the intrinsic momenta of the target electrons. This effect is largest in devices with very small acceptance or very high resolution in laboratory scattering angle. We use a high resolution polarimeter in the linac of the polarized SLAC Linear Collider to study this effect. We observe that the inclusion of the effect alters the measured beam polarization by -14% of itself and produces a result that is consistent with measurements from a Compton polarimeter. Additionally, the inclusion of the effect is necessary to correctly simulate the observed shape of the two-body elastic scattering peak. Comment: 29 pages, uuencoded gzip-compressed postscript (351 kb). Uncompressed postscript file (898 kb) available to DECNET users as SLC::USER_DISK_SLC1:[MORRIS]levpre.ps
12/1994;
-
F. Butler,
J. Boyer,
G. Gidal, G. Abrams, D. Amidei,
A. R. Baden,
M. S. Gold, G. Goldhaber, L. Golding,
J. Haggerty,
D. Herrup,
I. Juricic,
J. A. Kadyk, M. E. Levi, M. E. Nelson, P. C. Rowson, [......],
and D. R. Wood G. H. Trilling,
K. Riles, M. L. Perl, T. Barklow, A. Boyarski, P. R. Burchat,
D. L. Burke, J. M. Dorfan, G. J. Feldman, L. Gladney,
G. Hanson, K. Hayes, R. J. Hollebeek,
W. R. Innes, J. A. Jaros, D. Karlen,
S. R. Klein, A. J. Lankford, R. R. Larsen, B. W. LeClaire,
N. S. Lockyer,
R. A. Ong V. Lüth,
and J. M. Yelton B. Richter,
T. Schaad
[show abstract]
[hide abstract]
ABSTRACT: Using 203 pb-1 of data collected by the Mark II detector at the SLAC storage ring PEP, we have measured the radiative width of the η′ for quasireal photons. The width is separately measured in the three reactions e+e-→e+e-η0π+π-, η0→γγ; e+e-→e+e-η0π+π-; η0→π+π-(π0,γ), and e+e-→e+e-ρ0γ, giving a statistically weighted average two-photon width of Γη′→γγ=4.57±0.25±0.44 keV. As a byproduct of the study of the decay mode η′→ργ, we also measured the two-photon decay width of the a2(1320) as Γa2(1320)→γγ=1.03±0.13±0.21 keV.
Phys. Rev. D. 08/1990; 42(5).
-
J. Boyer,
F. Butler,
G. Gidal, G. Abrams, D. Amidei,
A. R. Baden,
L. Golding M. S. Gold,
J. Haggerty G. Goldhaber,
D. Herrup,
I. Juricic,
J. A. Kadyk, M. E. Levi, M. E. Nelson, P. C. Rowson, [......],
and D. R. Wood G. H. Trilling,
T. Barklow, A. Boyarski, P. Burchat,
D. L. Burke, D. Cords, J. M. Dorfan, G. J. Feldman, L. Gladney,
G. Hanson, K. Hayes, R. J. Hollebeek,
W. R. Innes, J. A. Jaros, D. Karlen,
A. J. Lankford, R. R. Larsen, B. W. LeClaire,
N. S. Lockyer,
R. A. Ong V. Lüth,
M. L. Perl, B. Richter, K. Riles, and J. M. Yelton,
T. Schaad
[show abstract]
[hide abstract]
ABSTRACT: We present a new high-statistics measurement of the cross section for the process e+e-→e+e-π+π- at a center-of-mass energy of 29 GeV for invariant pion-pair masses M(π+π-) between 350 MeV/c2 and 1.6 GeV/c2. We observe the f2(1270) and measure its radiative width to be 3.15±0.04±0.39 keV. We also observe an enhancement in the π+π- spectrum near 1 GeV. General agreement is found with unitarized models of the γγ→π+π- reaction that include final-state interactions.
Phys. Rev. D. 08/1990; 42(5).
