42826202
Observation of the Top Quark.
The D0 collaboration reports on a search for the Standard Model top quark in p{bar p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron, with an integrated luminosity of approximately 50 pb{sup {minus}1}. We have searched for t{bar t} production in the dilepton and single lepton decay channels, with and without tagging of b quark jets. We observe 17 events with an expected background of 3.8 {plus_minus} 0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2 {times} 10{sup {minus}6} (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measure its mass to be 199{sub {minus}21}{sup +19} (stat.) {plus_minus}22 (syst.) GeV/c{sup 2} and its production cross section to be 6.4 {plus_minus} 2.2 pb.
124796127
$Z \gamma$ production in $\bar{p} p$ collisions $S^{(1/2)}$ = 1.8-TeV and limits on anomalous $Z Z \gamma$ and $Z \gamma \gamma$ couplings
We present a study of Zγ+X production in p¯p collisions at √s=1.8TeV from 97 (87)pb−1 of data collected in the eeγ (μμγ) decay channel with the D0 detector at Fermilab. The event yield and kinematic characteristics are consistent with the standard model predictions. We obtain limits on anomalous ZZγ and Zγγ couplings for form factor scales Λ=500GeV and Λ=750GeV. Combining this analysis with our previous results yields 95% C.L. limits |hZ30|<0.36, |hZ40|<0.05, |hγ30|<0.37, and |hγ40|<0.05 for a form factor scale Λ=750GeV.
124156746
Amplitude analysis of the K anti K system in J/. psi. radiative decay
Preliminary results of a mass independent amplitude analysis of J/{psi} radiative decays into K {bar K} final states are presented. A large component of spin zero is observed at the f{sub 2}/{theta}(1720) mass region; however, a small spin two component at this mass region cannot be excluded with the present statistics. 9 refs., 7 figs.
117769557
Inclusive $\mu$ and $B$ quark production cross-sections in $p\bar{p}$ collisions at $\sqrt{s} = 1.8$ TeV
We report on a preliminary measurement of the inclusive dimuon cross section in p{bar p} collisions at {radical}s = 1.8 TeV using the D0 detector at the Fermilab Tevatron. From these results, we extract the inclusive b-quark production cross section for the kinematic range {vert_bar}y{sup b}{vert_bar} < 1.0 and 9 GeV/c < p{sub T}{sup b min} < 25 GeV/c. The difference in azimuthal angle in the transverse plane for dimuon pairs from b{bar b} production is also shown.
43756291
Top quark search with the D0 1992-1993 data sample.
We present results on the search for the top quark in {ital p{bar p}} collisions at {radical}{ital s} =1.8 TeV with an integrated luminosity of 13.5{plus_minus}1.6 pb{sup {minus}1}. We have considered {ital t{bar t}} production in the standard model using electron and muon dilepton decay channels ({ital t{bar t}}{r_arrow}{ital e}{mu}+jets, {ital ee}+jets, and {mu}{mu}+jets) and single-lepton decay channels ({ital t{bar t}}{r_arrow}{ital e}+jets and {mu}+jets) with and without tagging of {ital b} quark jets. An analysis of these data optimized for top quark masses below 140 GeV/{ital c}{sup 2} gives a lower top quark mass limit of 128 GeV/{ital c}{sup 2}. An analysis optimized for higher top quark masses yields 9 events with an expected background of 3.8{plus_minus}0.9. If we assume that the excess is due to {ital t{bar t}} production, and assuming a top quark mass of 180 GeV/{ital c}{sup 2}, we obtain a cross section of 8.2{plus_minus}5.1 pb.
122759006
Studies of gauge boson pair production and trilinear couplings
The gauge boson pair production processes W{gamma}, WW, WZ, and Z{gamma} were studied using p{bar p} collisions corresponding to an integrated luminosity of approximately 14 pb{sup {minus}1} at a center-of-mass energy of {radical} (s) =1.8 TeV. Analysis of W{gamma} production with subsequent W boson decay to scr(l){nu} (scr(l)=e,{mu}) is reported, including a fit to the p{sub T} spectrum of the photons which leads to limits on anomalous WW{gamma} couplings. A search for WW production with subsequent decay to scr(l)scr({bar l}){nu}{bar {nu}} (scr(l)=e,{mu}) is presented, leading to an upper limit on the WW production cross section and limits on anomalous WW{gamma} and WWZ couplings. A search for high p{sub T} W bosons in WW and WZ production is described, where one W boson decays to an electron and a neutrino and the second W boson or the Z boson decays to two jets. A maximum likelihood fit to the p{sub T} spectrum of W bosons resulted in limits on anomalous WW{gamma} and WWZ couplings. A combined fit to the three data sets which provided the tightest limits on anomalous WW{gamma} and WWZ couplings is also described. Limits on anomalous ZZ{gamma} and Z{gamma}{gamma} couplings are presented from an analysis of the photonmore » E{sub T} spectrum in Z{gamma} events in the decay channels (ee, {mu}{mu}, and{nu}{nu}) of the Z boson. {copyright} {ital 1997} {ital The American Physical Society}« less
44727684
BRST quantization of topological field theory.
The canonical quantization of the topological field-theory model {Sigma}, proposed by Horowitz, is examined through the Becchi-Rouet-Stora-Tyutin approach. With this approach we have a manifestly covariant description of a certain class of topological quantum field theories. However, if {ital M} in the present model is any orientable four-dimensional manifold, one would end up with different theories when different polarizations are chosen. Therefore a restriction {ital M}={ital R}{sup 1}{times}{Sigma}, as pointed out by Horowitz, is required for consistency.
125927421
Measurement of the mass of the tau lepton.
Author(s): Bai, JZ; Bardon, O; Becker-Szendy, RA; Blum, I; Breakstone, A; Burnett, T; Chen, GP; Chen, HF | Abstract: A data-driven energy scan in the immediate vicinity of the τ pair production threshold has been performed using the Beijing Spectrometer at the Beijing Electron-Positron Collider. Approximately 5pb-1of data, distributed over 12 scan points, have been collected. A previous mass value for the τ lepton, obtained using only the eµ final state, has been published. In this paper, the final BES result on the mass measurement is presented. The analysis is based on the combined data from the ee, eµ, eh, µµ, µh, and hh final states, where h denotes a charged Π or K. A maximum likelihood fit to the τ pair production cross section data yields the value mT=1776.96-0.21-0.17+0.18+0.25. © 1995 The American Physical Society.
43203688
Remark on charm quark fragmentation to D** mesons.
The observed [ital D][sup **] mesons have [ital c[bar q]] flavor quantum numbers and a spin-parity of the light degrees of freedom [ital s][sub [ital l]][sup [pi]][sub [ital l]]=3/2[sup +]. In the [ital m][sub [ital c]][r arrow][infinity] limit the spin of the charm quark is conserved and the [ital c][r arrow][ital D][sup **] fragmentation process is characterized by the probability for the charm quark to fragment to a [ital D][sup **] meson with a given helicity for the light degrees of freedom. We consider the calculated [ital b][r arrow][ital B][sub [ital c]][sup **] fragmentation functions in the limit [ital m][sub [ital c]]/[ital m][sub [ital b]][r arrow]0 as a qualitative model for the [ital c][r arrow][ital D][sup **] fragmentation functions. We find that in this model charm quark fragmentation to [ital s][sub [ital l]][sup [pi]][sub [ital l]]=3/2[sup +] light degrees of freedom with helicities [plus minus]1/2 is favored over fragmentation to [ital s][sub [ital l]][sup [pi]][sub [ital l]]=3/2[sup +] light degrees of freedom with helicities [plus minus]3/2.
28164273
General theory of quantum statistics with internal degrees of freedom in two dimensions.
The general theory of θ statistics with internal degrees of freedom is presented. The intrinsic parts of wave functions are expressed by means of the irreducible representations of the quantum group SU(2,q) with q=e −iθ . We show that the violation of P or T reflection symmetry is involved in two kinds of coproduct for constructing these representations
16855657
Critical statistical charge for anyonic superconductivity.
We examine a criterion for the anyonic superconductivity at zero temperature in Abelian matter-coupled Chern-Simons gauge-field theories in three dimensions. By solving the Dyson-Schwinger equations, we obtain a critical value of the statistical charge for the superconducting phase in a massless fermion-Chern-Simons model. {copyright} {ital 1996 The American Physical Society.}