共查询到20条相似文献,搜索用时 62 毫秒
1.
《Zeitschrift fur Physik C Particles and Fields》1996,69(4):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 the k ⊥ jet finder with y cut=0.02, we find $${«ngle n^{? ch.}»ngle {? gluon}?er «ngle n^{? ch.}»ngle {? b} {? quark}}=1.089pm 0.024 ({? stat.})pm0.024 ({? syst.})$$ $${«ngle n^{? ch.}»ngle {? gluon}?er «ngle n^{? ch.}»ngle {? uds} {? quark}}=1.390pm 0.038 ({? stat.})pm0.032 ({? syst.})$$ 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.
H. -J. Grabosch H. H. Kaufmann U. Krecker R. Nahnhauer S. Nowak S. Schlenstedt H. Vogt E. P. Kuznetsov V. V. Ammosov D. S. Baranov V. I. Ermolaev A. A. Ivanilov P. V. Ivanov V. I. Konyushko V. M. Korablev V. A. Korotkov V. A. Krupnov V. V. Makeev A. G. Myagkov A. Yu. Polyarush A. A. Sokolov SKAT-Collaboration 《Zeitschrift fur Physik C Particles and Fields》1986,31(2):203-211
Studying the coherent diffractive production of pions in neutrino and antineutrino scattering off the nuclei of freon molecules we have observed for the first time in one experiment all three states of the isospin triplet of the axial part of the weak charged and neutral currents. For the corresponding cross sections we derive $$\begin{array}{*{20}c} {\sigma _{coh}^v (\pi ^ + ) = (106 \pm 16) \cdot 10^{ - 40} {{cm^2 } \mathord{\left/ {\vphantom {{cm^2 } {\left\langle {nucl.} \right\rangle }}} \right. \kern-\nulldelimiterspace} {\left\langle {nucl.} \right\rangle }}} \\ {\sigma _{coh}^{\bar v} (\pi ^ - ) = (113 \pm 35) \cdot 10^{ - 40} {{cm^2 } \mathord{\left/ {\vphantom {{cm^2 } {\left\langle {nucl.} \right\rangle }}} \right. \kern-\nulldelimiterspace} {\left\langle {nucl.} \right\rangle }}and} \\ {\sigma _{coh}^v (\pi ^0 ) = (52 \pm 19) \cdot 10^{ - 40} {{cm^2 } \mathord{\left/ {\vphantom {{cm^2 } {\left\langle {nucl.} \right\rangle }}} \right. \kern-\nulldelimiterspace} {\left\langle {nucl.} \right\rangle }}} \\ \end{array} $$ . Comparing our data with theoretical predictions based on the standard model of weak interactions we find reasonable agreement. Independently from any model of coherent pion production we determine the isovector axial vector coupling constant to be |β|=0.99±0.20. 相似文献
3.
P. Abreu et al. 《The European Physical Journal C - Particles and Fields》1999,9(3):367-381
The b[`b]\mbox{b}\bar{\mbox{b}} forward-backward asymmetry has been determined from the average charge flow measured in a sample of 3,500,000 hadronic Z decays collected with the DELPHI detector in 1992–1995. The measurement is performed in an enriched b[`b]\mbox{b}\bar{\mbox{b}} sample selected using an impact parameter tag and results in the following values for the b[`b]\mbox{b}\bar{\mbox{b}} forward-backward asymmetry: $
\begin{gathered}
A_{FB}^{b\bar b} \left( {89.55 GeV} \right) = 0.068 \pm 0.018 \left( {stat.} \right) \pm 0.0013\left( {syst.} \right) \hfill \\
A_{FB}^{b\bar b} \left( {91.26 GeV} \right) = 0.0982 \pm 0.0047 \left( {stat.} \right) \pm 0.0016\left( {syst.} \right) \hfill \\
A_{FB}^{b\bar b} \left( {92.94 GeV} \right) = 0.123 \pm 0.016 \left( {stat.} \right) \pm 0.0027\left( {syst.} \right) \hfill \\
\end{gathered}
$
\begin{gathered}
A_{FB}^{b\bar b} \left( {89.55 GeV} \right) = 0.068 \pm 0.018 \left( {stat.} \right) \pm 0.0013\left( {syst.} \right) \hfill \\
A_{FB}^{b\bar b} \left( {91.26 GeV} \right) = 0.0982 \pm 0.0047 \left( {stat.} \right) \pm 0.0016\left( {syst.} \right) \hfill \\
A_{FB}^{b\bar b} \left( {92.94 GeV} \right) = 0.123 \pm 0.016 \left( {stat.} \right) \pm 0.0027\left( {syst.} \right) \hfill \\
\end{gathered}
The b[`b]\mbox{b}\bar{\mbox{b}} charge separation required for this analysis is directly measured in the b tagged sample, while the other charge separations are obtained from a fragmentation model precisely calibrated to data. The effective weak mixing angle is deduced from the measurement to be: $
sin^2 \theta _{eff}^1 = 0.23186 \pm 0.00083
$
sin^2 \theta _{eff}^1 = 0.23186 \pm 0.00083
相似文献
4.
Blinov A. E. Blinov V. E. Bondar A. E. Bukin A. D. Groshev V. R. Klimenko S. G. Onuchin A. P. Panin V. S. Protopopov I. Ya. Shamov A. G. Sidorov V. A. Skovpen Yu. I. Skrinsky A. N. Tayursky V. A. Telnov V. I. Tikhonov Yu. A. Tumaikin G. M. Undrus A. E. Vorobiov A. I. Zhilich V. N. 《Zeitschrift fur Physik C Particles and Fields》1994,62(3):367-370
Using the MD-1 detector at the VEPP-4e
+
e
– strorage ring we have measured the inclusive and370-1 production rates in direct (1S) decays
相似文献
5.
Ross Graham 《Journal of statistical physics》1982,29(2):185-191
We prove the following inequality for the truncated correlation in the Ising model in zero external field: $$\begin{gathered} \langle \sigma _i \sigma _j \sigma _k \sigma _l \rangle - \langle \sigma _i \sigma _j \rangle \langle \sigma _k \sigma _l \rangle - \langle \sigma _i \sigma _k \rangle \langle \sigma _j \sigma _l \rangle - \langle \sigma _i \sigma _l \rangle \langle \sigma _j \sigma _k \rangle \hfill \\ \leqslant - 2\langle \sigma _i \sigma _m \rangle \langle \sigma _j \sigma _m \rangle \langle \sigma _k \sigma _m \rangle \langle \sigma _l \sigma _m \rangle \hfill \\ - 2 \left( {\langle \sigma _i \sigma _k \rangle - \langle \sigma _i \sigma _m \rangle \langle \sigma _m \sigma _k \rangle } \right) \left( {\langle \sigma _j \sigma _k \rangle - \langle \sigma _j \sigma _m \rangle \langle \sigma _m \sigma _k \rangle } \right)\langle \sigma _k \sigma _l \rangle \hfill \\ - 2 \langle \sigma _i \sigma _m \rangle \langle \sigma _j \sigma _m \rangle \left( {\langle \sigma _i \sigma _k \rangle - \langle \sigma _i \sigma _m \rangle \langle \sigma _m \sigma _k \rangle } \right)\left( {\langle \sigma _i \sigma _l \rangle - \langle \sigma _i \sigma _m \rangle \langle \sigma _m \sigma _l \rangle } \right) \hfill \\ \end{gathered} $$ This inequality is a strengthening of the Lebowitz inequality for the four-point function and implies the following improvement of the GHS inequality: $$\langle \sigma _i ;\sigma ;_j \sigma _k \rangle ^T \leqslant - 2\langle \sigma _i ;\sigma _k \rangle ^T \langle \sigma _j ;\sigma _k \rangle ^T \langle \sigma _k \rangle $$ This in turn implies the critical exponent inequality $$\Delta '_3 \geqslant \gamma ' - \beta $$ 相似文献
6.
D. Krpić R. Stepić I. Bikit J. Milanović R. Vukanović 《Zeitschrift für Physik A Hadrons and Nuclei》1971,243(5):452-463
TheL-subshell conversion for 77 keV transition andK,L 1,L 2-shell conversion for 191 keV transition in197Au, as well asK-shell conversion transition of 158 keV in199Hg were measured by means of Π√2-iron free electron spectrometer. Relative gamma-ray intensities have been determined by Ge(Li) spectrometer. From these measurements the α K conversion coefficient value has been deduced for 191 keV transition as αK(191 keV)=0.86±0.03. This value shows that the spin of the level at 268 keV in197Au is 3/2+. For the penetration parameter (λ) and intensity ratio \(\left( {\delta ^2 = \frac{{\left\langle {E2} \right\rangle ^2 }}{{\left\langle {MI} \right\rangle ^2 }}} \right)\) the following values are obtained: $$\begin{gathered} \lambda = 3.4 \pm _{1.5}^{1.9} \delta ^2 = 0.11 \pm 0.03for 77 keV transition \hfill \\ \lambda = 3.2 \pm _{0.6}^{0.8} \delta ^2 = 0.17 \pm 0.04for 191 keV transition. \hfill \\ \end{gathered} $$ The agreement of these results with the predictions of De Shalit model is discussed. 相似文献
7.
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:
|