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.
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.
124309222
Search for new particles decaying to two jets with the D0 detector
Results from a search for new particles decaying to dijets in fi = 1.8 TeV pp collisions using the DO 1992-93 and 1994-95 data samples (104 pb-1) are presented. We exclude at the 95% confidence level the production of excited quarks with masses below 725 GeV/ c2, an additional standard model W boson with masses between 340 and 680 GeV/ c2 and an additional standard model 2 boson with masses between 365 and 615 GeV/c2. *Submitted to the International Europhysics Conference on High Energy Physics, August 19 26, 1997, Jerusalem, Israel.
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
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.
17975331
ZN phases in hot gauge theories.
We argue that the {ital Z}{sub {ital N}} phases of hot gauge theories cannot be realized as a real system with a Hermitian density matrix.
28535306
Implications of a cosmological constant varying as R-2.
We advocate the possibility that the (effective) cosmological constant {Lambda} varies in time as {ital R}{sup {minus}2}, {ital R} being the scale factor of our expanding Universe. This behavior can be obtained under some simple and general assumptions in conformity with quantum cosmology. After pointing out several advantages worth noticing, we show that such a time-varying {Lambda} leads to no conflict with existing observations. However, it does change the predictions of the standard cosmology in the matter-dominated epoch and alleviates some problems in reconciling observations with the inflationary scenario. In particular, this medium'' time variation of {Lambda} leads to creation of matter with a rate at present which is comparable to that in the steady-state cosmology.
10101389
Symplectic structure of Yang-Mills theory in BRST formalism.
We construct a symplectic form for classical Yang-Mills theory, which is manifestly covariant and Becchi-Rouet-Stora-Tyutin invariant. This suggests an approach to eliminate the degeneracy that exists in the initially given two-form for the theory.