We have measured the inclusive prompt electron cross section over a wide momentum range (P>0.5 GeV/c) with the PEP-4 TPC detector. The semielectronic branching fractions of thec andb quarks are (9.1±0.9 (stat.)±1.3 (syst.))% and (11.0±1.8±1.0)%, respectively. Theb quark fragmentation function peaks at highz with 〈zb〉=0.74±0.05±0.03. The axial couplings to the neutral current areac=2.3±1.4±1.0 for thec quark andab=−2.0±1.9±0.5 for theb quark.
No description provided.
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We have studied the production of prompt muons in hadronic events from e+e− annihilation at a center-of-mass energy of 29 GeV with the PEP4-TPC (Time Projection Chamber) detector. The muon p and pt distributions are well described by a combination of bottom- and charm-quark decays, with fitted semimuonic branching fractions of (15.2±1.9±1.2)% and (6.9±1.1±1.1)%, respectively. The muon spectra imply hard fragmentation functions for both b and c quarks, with 〈z(b quark)〉=0.80±0.05±0.05 and 〈z(c quark)〉=0.60±0.06±0.04. We derive neutral-current axial-vector couplings of a(b quark)=-0.9±1.1±0.3 and a(c quark)=1.5±1.5±0.5 from the forward-backward asymmetries.
PT is the transverse momentum of the muon relative to the event thrust axis.
PT is the transverse momentum of the MUON relative to the event thrust axis. At this table MUON is from JET and its PT < 1 GeV/c.
PT is the transverse momentum of the MUON relative to the event thrust axis. At this table MUON is from JET and its PT > 1 GeV/c.
Using data from the TPC/Two-Gamma experiment at the SLAC e+e− storage ring PEP, a C=+1 resonance has been observed in the π+π−π0γ final state resulting from the fusion of one nearly real and one quite virtual photon. The actual decay channel is probably π+π−π0π0, where one final-state photon is not detected, and the mass of the fully reconstructed state would be approximately 1525 MeV. A four-pion decay mode in turn implies that the resonance has even isospin. The nonobservation of this R(1525) when both initial-state photons are nearly real suggests a spin-1 assignment. Since the large measured value of the product of the branching ratio into π+π−π0π0 and the γγ coupling makes it unlikely that this state is the mostly s¯s f1(1510), its interpretation may lie outside of conventional meson spectroscopy. There is a second, less-significant enhancement observed in the same reaction at a four-pion mass centered around 2020 MeV.
No description provided.
Coupling parameter times the effective form factor.
We have measured the polarization of D*, the energy dependence of the polarization, and the spin-density matrix of D* in e+e− annihilation at a center-of-mass energy of 29 GeV using the Time Projection Chamber detector at the SLAC storage ring PEP. In 147 pb−1 of data we see no strong evidence for polarization, alignment, or final-state interactions in this fragmentation process.
Polarization is the factor alpha(z) in the expression d width (D*-->D pi)/domega = C(1+alpha(z)cos(theta)**2).
Spin density matrices for D* --> D0 pi+.
We report measurements of π±K±, and p, p¯ inclusive cross sections and fractions in e+e− annihilation at s=29 GeV, for the momentum interval 0.01<z=ppbeam<0.90. The analysis is based on approximately 70 pb−1 of data collected with the TPC2γ detector facility at the SLAC storage ring PEP. Detector upgrades result in significantly improved momentum coverage and precision of the data, compared to previous measurements.
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This paper presents the first measurement of the inclusive J/Psi production cross section in the forward pseudorapidity region 2.5<|eta|<3.7 in ppbar collisions at sqrt(s)=1.8TeV. The results are based on 9.8 pb-1 of data collected using the D0 detector at the Fermilab Tevatron Collider. The inclusive J/Psi cross section for transverse momenta between 1 and 16 GeV/c is compared with theoretical models of charmonium production.
Only statistical errors are shown. Cross section tines branching ratio.
Evidence of anomalous WW and WZ production was sought in pbar{p} collisions at a center-of-mass energy of sqrt(s) = 1.8 TeV. The final states $WW (WZ) to mu-nu-jet-jet + X, WZ to mu-nu-e-e + X and WZ to e-nu-e-e + X were studied using a data sample corresponding to an integrated luminosity of approximately 90 pb-1. No evidence of anomalous diboson production was found. Limits were set on anomalous WWgamma and WWZ couplings and were combined with our previous results. The combined 95% confidence level anomalous coupling limits for Lambda=2 TeV are -0.25 LE Delta-kappa LE 0.39 (lambda=0) and -0.18 LE lambda LE 0.19 (Delta \kappa = 0), assuming the WWgamma couplings are equal to the WWZ couplings.
CONST(NAME=SCALE) is the model parameter, used in the modification of the couplings as follows: g = g0/(1 + M(gamma Z)**2/CONST(NAME=SCALE)**2)**n. KAPPA_GZ means KAPPA_GAMMA = KAPPA_Z. LAMBDA_GZ means LAMBDA_GAMMA = LAMBDA_Z.
CONST(NAME=SCALE) is the model parameter, used in the modification of the couplings as follows: g = g0/(1 + M(gamma Z)**2/CONST(NAME=SCALE)**2)**n.
Using the DZero detector at the 1.8 TeV pbarp Fermilab Tevatron collider, we have measured the inclusive dijet mass spectrum in the central pseudorapidity region |eta_jet| < 1.0 for dijet masses greater than 200 Gev/c^2. We have also measured the ratio of spectra sigma(|eta_jet| < 0.5)/sigma(0.5 < |eta_jet| < 1.0). The order alpha_s^3 QCD predictions are in good agreement with the data and we rule out models of quark compositeness with a contact interaction scale < 2.4 TeV at the 95% confidence level.
Dijet cross section for ABS(ETARAP)<1.0.
Ratio of cross sections for ABS(ETARAP) < 0.5 / 0.5 < ABS(ETARAP) < 1.0.
We present a study of Z +gamma + X production in p-bar p collisions at sqrt{S}=1.8 TeV from 97 (87) pb^{-1} of data collected in the eegamma (mumugamma) 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 ZZgamma and Zgammagamma couplings for form factor scales Lambda = 500 GeV and Lambda = 750 GeV. Combining this analysis with our previous results yields 95% CL limits |h{Z}_{30}| < 0.36, |h{Z}_{40}| < 0.05, |h{gamma}_{30}| < 0.37, and |h{gamma}_{40}| < 0.05 for a form factor scale Lambda=750 GeV.
CONST(NAME=SCALE) is the model parameter, used in the modification of the couplings as follows: h = hi0/(1 + M(gamma Z)**2/CONT(NAME=SCALE)**2)**n. See article for details.
We have searched for first generation scalar leptoquark (LQ) pairs in the enu+jets channel using ppbar collider data (integrated luminosity= 115 pb^-1) collected by the DZero experiment at the Fermilab Tevatron during 1992-96. The analysis yields no candidate events. We combine the results with those from the ee+jets and nunu+jets channels to obtain 95% confidence level (CL) upper limits on the LQ pair production cross section as a function of mass and of beta, the branching fraction to a charged lepton. Comparing with the next-to-leading order theory, we set 95% CL lower limits on the LQ mass of 225, 204, and 79 GeV/c^2 for beta=1, 1/2, and 0, respectively.
The cross section values are extracted with the assumption that BR(LQ --> EQUARK) = 1/2.
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