We have analyzed 2560 events in the final-state K O 1 K O 1 n produced in π − p interactions at 5, 7 and 12 GeV/ c . We observe the S ∗ (1070), f O and A 2 decaying into K O 1 K O 1 . Resonance parameters, cross sections, and branching ratios are given.
Cross section times branching ratio.
We report the observation and measurement of the rate of diffractive dijet production at the Fermilab Tevatron p¯p collider at s=1.8TeV. In events with two jets of ET>20GeV, 1.8<|η|<3.5, and η1η2>0, we find that the diffractive to nondiffractive production ratio is RJJ=[0.75±0.05(stat)±0.09(syst)]%. By comparing this result, in combination with our measured rate for diffractive W boson production reported previously, with predictions based on a hard partonic pomeron structure, we determine the pomeron gluon fraction to be fg=0.7±0.2.
No description provided.
We present the first observation of the all hadronic decay of tt¯ pairs. The analysis is performed using 109pb−1 of pp¯ collisions at s=1.8TeV collected with the Collider Detector at Fermilab. We observe an excess of events with five or more jets, including one or two b jets, relative to background expectations. Based on this excess we evaluate the production cross section to be in agreement with previous results. We measure the top mass to be 186±10±12GeV/c2.
The cross section is given in the paper at a TQ mass of 175 GeV. The values at TQ mass = (175 +- 10) GeV is evaluated as +20% and -12% as given in the paper. The statistical error has also been scaled.
The measured value of the top mass.
Using 4.8 fb$~{-1}$ of data taken with the CLEO II detector, the branching fraction for the Cabibbo-suppressed decay $D~+\to\pi~0\ell~+\nu$ measured relative to the Cabibbo favored decay $D~+\to\bar{K~0}\ell~+\nu$ is found to be $0.046\pm 0.014\pm 0.017$. Using $V_{cs}$ and $V_{cd}$ from unitarity constraints, we determine $| f_+~{\pi}(0)/f_+~K(0)|~2=0.9\pm 0.3\pm 0.3$ We also present a 90% confidence level upper limit for the branching ratio of the decay $D~+ \to \eta e~+\nu_e$ relative to that for $D~+ \to \pi~0 e~+\nu_e$ of 1.5.
Formfactors for the D+ (D-) decay into pseudoscalar P. Charge conjugate states are implied. LEPTON+ means E+ or MU+. VCD and VCS are the elements of the CKM matrix (See R.M.Barnett et al (PDG), PR D54, 1 (1996)).
This letter describes a measurement of one of the anomalous triple gauge boson couplings using the first data recorded by the OPAL detector at LEP2. A total of 28 W-pair candidates have been selected for an integrated luminosity of 9.89±0.06 pb −1 recorded at a centre-of-mass energy of 161 GeV. We use these data to place constraints upon the coupling parameter α W φ . We analyse the predicted variation of the total cross-section for all observed channels and the distribution of kinematic variables in the semileptonic decay channels. We measure α W φ to be −0.61 −0.61 0.73 ±0.35, which is consistent with the Standard Model expectation of zero.
ALPHA-W-PHI is the triple gauge boson couplings (TGC). For definition see 'Physics at LEP2', Ed. G. Altarelli, CERN 96-01 (1996), vol. 1.
The cross section and tensor analysing power t_20 of the d\vec{d}->eta 4He reaction have been measured at six c.m. momenta, 10 < p(eta) < 90 MeV/c. The threshold value of t_20 is consistent with 1/\sqrt{2}, which follows from parity conservation and Bose symmetry. The much slower momentum variation observed for the reaction amplitude, as compared to that for the analogous pd->eta 3He case, suggests strongly the existence of a quasi-bound state in the eta-4He system and optical model fits indicate that this probably also the case for eta-3He.
The spin-averaged amplitude squared is defined as follows: ABS(AMP)**2 = (P_deut/P_eta)*D(SIG)/D(OMEGA) and obtained by assuming the angular distributions to be isotropic. The errors in this quantity includes a contribution from Delta(P_eta). The statistical error of about 2% are added quadratically to the systemat ic error.
We present results on the production of high transverse momentum charm mesons in collisions of 515 GeV/c negative pions with beryllium and copper targets. The experiment recorded a large sample of events containing high transverse momentum showers detected in an electromagnetic calorimeter. From these data, a sample of charm mesons has been reconstructed via their decay into the fully charged K pi pi mode. A measurement of the single inclusive transverse momentum distribution of charged D mesons from 1 to 8 GeV/c is presented. An extrapolation of the measured differential cross section yields an integrated charged D cross section of 11.4+-2.7(stat)+-3.3(syst) microbarns per nucleon for charged D mesons with Feynman x greater than zero. The data are compared with expectations based upon next-to-leading order perturbative QCD, as well as with results from PYTHIA. We also compare our integrated charged D cross section with measurements from other experiments.
The mean values of PT are the PT values which correspond to the average values of the cross sections in the appropriate bins as determined by the PYTHIA Mponte-Carlo.
The PYTHIA Monte-Carlo simulation is used for extrapolation of D+- cross section for XL < -0.2.
Using data collected from 1992 to 1995 with the ALEPH detector at LEP, a measurement of the colour factor ratios CA/CF and TF /CF and the strong coupling constant αs = CFαs(MZ)/(2π) has been performed by fitting theoretical predictions simultaneously to the measured differential two-jet rate and angular distributions in four-jet events. The result is found to be in excellent agreement with QCD, {fx4-1} Fixing CA/CF and TF/CF to the QCD values permits a determination of αs(MZ) and ηf, the number of active flavours. With this measurement the existence of a gluino with mass below 6.3 GeV/c2 is excluded at 95% confidence level.
Fit A: using all kinematical distributions. NC, CF, and TF are the color factors for SU(3) group, NF is the number of the active flavors.
Fit B: using all kinematical distributions, but QCD magnitudes for color factors are used: FA(DEF=NC/CF)) = 2.25 and TF/CF = 0.375. NC, CF, and TF are the color factors for SU(3) group, NF is the number of the active flavors.
Fit C: the QCD magnitudes for color factors and NF = 5 are used.
A fresh analysis is reported of high statistics Crystal Barrel data on p p → 3π 0 , ηηπ 0 , ηπ 0 π 0 and ηη ′ π 0 at rest. This analysis is made fully consistent with CERN-Munich data on π + π − → π + π − up to a mass of 1900 MeV, with GAMS data on π + π − → π 0 π 0 , and with BNL and ANL data on π + π − → K K , which are fitted simultaneously. There is evidence for an I = 0, J PC = 2 ++ resonance with weak (≤ 7%) coupling to ππ, strong coupling to both ϱϱ and ωω and pole position 1534 - i90 MeV. This resonance agrees qualitatively with GAMS and VES data on ππ → ωω, previously interpreted in terms of a resonance at 1590–1640 MeV. New masses and widths for (A) ƒ 0 (1370) and (B) ƒ 0 (1500) , fitted to all eight data sets, are M A = 1300 ± 15 Mev, Γ A = 230 ± 15 MeV, M B = 1500 ± 8 MeV, Γ B = 132 ± 15 MeV. Branching ratios to ππ and ηη are given, and differ significantly from earlier determinations because of a new procedure.
A fraction of the initial P-state annihilation into F2(1270) cannot be ruled out. Therefore, the ratio magnitudes include the contribution due to this channel. MESON0 denotes A2(1630) state, not present in RPP.
We have measured the ZZ-gamma and Z-gamma-gamma couplings by studying p-bar p -> (missing ET) gamma + X events at sqrt(s)=1.8 TeV with the D0 detector at the Fermilab Tevatron Collider. This first study of hadronic Z-gamma production in the neutrino decay channel gives the most stringent limits on anomalous couplings available. A fit to the transverse energy spectrum of the photon in the candidate event sample, based on a data set corresponding to an integrated luminosity of 13.1 pb~(-1), yields 95% CL limits on the anomalous CP-conserving ZZ-gamma couplings of |h~Z_(30)|<0.9, |h~Z_(40)|<0.21, for a form-factor scale Lambda = 500 GeV. Combining these results with our previous measurement using Z -> ee and mu-mu yields the limits:|h~Z_(30)|<0.8, |h~Z_(40)|<0.19 (Lambda = 500 GeV) and |h~Z_(30)|<0.4, |h~Z_(40)|<0.06 (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.. The data with Z --> lepton+ lepton- is taken from S.Abachi, PRL 75, 1028.
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