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1.
OPAL Collaboration G. Alexander J. Allison N. Altekamp K. Ametewee K. J. Anderson S. Anderson S. Arcelli S. Asai D. Axen et al. 《Zeitschrift fur Physik C Particles and Fields》1995,69(1):543-560
Symmetric three-jet events are selected from hadronic Z0 decays such that the two lower energy jets are each produced at an angle of about 150° with respect to the highest energy
jet. In some cases, a displaced secondary vertex is reconstructed in one of the two lower energy jets, which permits the other
lower energy jet to be identified as a gluon jet through anti-tagging. In other cases, the highest energy jet is tagged as
a b jet or as a light quark (uds) jet using secondary vertex or track impact parameter and momentum information. Comparing
the two lower energy jets of the events with a tag in the highest energy jet to the anti-tagged gluon jets yields a direct
comparison of b, uds and gluon jets, which are produced with the same energy of about 24 GeV and under the same conditions.
We observe b jets and gluon jets to have similar properties as measured by the angular distribution of particle energy around
the jet directions and by the fragmentation functions. In contrast, gluon jets are found to be significantly broader and to
have a markedly softer fragmentation function than uds jets. For thek
⊥ jet finder withy
cut=0.02, we find
as the ratios of the mean charged particle multiplicity in the gluon jets compared to the b and uds jets. Results are also
reported using the cone jet finder. 相似文献
2.
R. Akers G. Alexander J. Allison N. Altekamp K. Ametewee K. J. Anderson S. Anderson S. Arcelli S. Asai D. Axen et al. 《Zeitschrift fur Physik C Particles and Fields》1995,67(3):365-378
The forward-backward asymmetry of
has been measured using approximately 2.15 million hadronicZ
0 decays collected at the LEP e+e– collider with the OPAL detector. A lifetime tag technique was used to select an enriched
event sample. The measurement of the
asymmetry was then performed using a jet charge algorithm to determine the direction of the primary quark. Values of:
相似文献
3.
Moments of the hadronic invariant mass and of the lepton energy spectra in semileptonic B decays have been determined with
the data recorded by the DELPHI detector at LEP. From measurements of the inclusive b-hadron semileptonic decays, and imposing constraints from other measurements on b- and c-quark masses, the first three moments of the lepton energy distribution and of the hadronic mass distribution, have been
used to determine parameters which enter into the extraction of |Vcb| from the measurement of the inclusive b-hadron semileptonic decay width. The values obtained in the kinetic scheme are:
and include corrections at order 1/mb3. Using these results, and present measurements of the inclusive semileptonic decay partial width of b-hadrons at LEP, an accurate determination of |Vcb| is obtained:
Received: 26 April 2005, Revised: 16 September 2005, Published online: 16 November 2005 相似文献
4.
A novel high precision method measures the b-quark forward-backward asymmetry at the Z pole on a sample of 3,560,890 hadronic events collected with the DELPHI detector in 1992 to 2000. An enhanced impact parameter tag provides a high purity b sample. For event hemispheres with a reconstructed secondary vertex the charge of the corresponding quark or anti-quark is determined using a neural network which combines in an optimal way the full available charge information from the vertex charge, the jet charge and from identified leptons and hadrons. The probability of correctly identifying b-quarks and anti-quarks is measured on the data themselves comparing the rates of double hemisphere tagged like-sign and unlike-sign events. The b-quark forward-backward asymmetry is determined from the differential asymmetry, taking small corrections due to hemisphere correlations and background contributions into account. The results for different centre-of-mass energies are:
.Combining these results yields the b-quark pole asymmetry
Received: 22 July 2004, Revised: 9 December 2004, Published online: 4 February 2005 相似文献
5.
J. V. Allaby U. Amaldi G. Barbiellini M. Baubillier F. Bergsma A. Capone W. Flegel F. Grancagnolo L. Lanceri M. Metcalf C. Nieuwenhuis R. Pain J. Panman R. Plunkett K. Winter I. Abt J. Aspiazu A. Büngener F. W. Büsser P. D. Gall T. Hebbeker F. Niebergall P. Schütt P. Stähelin P. Gorbunov E. Grigoriev V. Khovansky A. Rosanov B. Borgia M. Diemoz C. Dionisi U. Dore F. Ferroni E. Longo P. F. Loverre L. Luminari P. Monacelli S. Morganti F. de Notaristefani C. Santoni CHARM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1988,38(3):403-410
New measurements of the total crosssections of charged-current interactions of muonneutrinos and antineutrinos on isoscalar nuclei have been performed. Data were recorded in an exposure of the CHARM detector in an 160 GeV narrow-band beam. The antineutrino flux was determined from the measurements of the pion and kaon flux, and independently from the muon flux measured in the shield; the two methods are found to agree. The neutrino flux was determined from the muon flux ratio forv μ and \(\bar v_\mu \) runs which was normalized to the antineutrino flux. The cross-section slopes thus determined are $$\begin{gathered} \sigma _T^{\bar v} /E = (0.335 \pm 0.004(stat) \hfill \\ \pm 0.010(syst)).10^{ - 38} cm^2 /(GeV \cdot nucleon) \hfill \\ \sigma _T^v /E = (0.686 \pm 0.002(stat) \hfill \\ \pm 0.020(syst)).10^{ - 38} cm^2 /(GeV \cdot nucleon) \hfill \\ \end{gathered} $$ The momentum sum of the quarks in the nucleon and the ratio of sea quark to total quark momentum are derived from the measurements. 相似文献
6.
P. Abreu W. Adam E. Agasi I. Ajinenko R. Aleksan G. D. Alekseev P. P. Allport S. Almehed F. M. L. Almeida S. J. Alvsvaag et al. 《Zeitschrift fur Physik C Particles and Fields》1995,66(3):341-354
The forward-backward asymmetries for the processes
and
at theZ resonance are measured using identifiedD
*± mesons. In 905,000 selected hadronic events, taken in 1991 and 1992 with the DEL-PHI detector at LEP, 4757D
*+D
0+ decays are reconstructed. Thec andb quark forward-backward asymmetries are determined to be:
|