Using a sample of 10 8 triggered events, produced in π − −Cu interactions at 350 GeV/ c , we have identified 26 beauty events. The estimated background in this sample is 0.6 ± 0.6 events. From these data, assuming a linear A-dependence, we measure a beauty production cross section integrated over all χ F of 5.7 −1.1 +1.3 (stat.) −0.5 +0.6 (syst.) nb/N.
No description provided.
An inclusive measurement of the average multiplicity of b b pairs from gluons, g b b , in hadronic Z 0 events collected by the DELPHI experiment at LEP, is presented. A counting technique, based on jet b -tagging in 4-jet events, has been used. Looking for secondary bottom production in events with production of any primary flavour, by requiring two b -tagged jets in well defined topological configurations, gave g b b = (0.21 ± 0.11 ( stat ) ± 0.09 ( syst ))% . This result was checked with a different method designed to select events with four b quarks in the final state. Agreement within the errors was found.
No description provided.
A measurement of the charm and bottom forward-backward asymmetry in e+e− annihilations is presented at energies on and around the peak of the Z0 resonance. Decays of the Z0 into charm and bottom quarks are tagged using D mesons identified in about 4 million hadronic decays of the Z0 boson recorded with the OPAL detector at LEP between 1990 and 1995. Approximately 33000 D mesons are tagged in seven different decay modes. From these the charm and bottom asymmetries are measured in three energy ranges around the Z0 peak: \(\matrix {A_{\rm FB}^{\rm c}=0.039\pm 0.051\pm 0.009\cr A_{\rm FB}^{\rm c}=0.063\pm 0.012\pm 0.006\cr A_{\rm FB}^{\rm c}=0.158\pm 0.041\pm 0.011}\)\(\matrix {A_{\rm FB}^{\rm b}=0.086\pm 0.108\pm 0.029\cr A_{\rm FB}^{\rm b}=0.094\pm 0.027\pm 0.022\cr A_{\rm FB}^{\rm b}=0.021\pm 0.090\pm 0.026}\)\(\matrix{\langle E_{cm}\rangle =89.45\ {\rm GeV}\cr \langle E_{cm}\rangle =91.22\ {\rm GeV}\cr \langle E_{cm}\rangle =93.00\ {\rm GeV}}\) The results are in agreement with the predictions of the standard model and other measurements at LEP.
Forward-backward asymmetry.
No description provided.
We report a measurement of the ratios of the decay rates of the B~+, B~0 and B~0_s mesons into exclusive final states containing a J/psi meson. The final states were selected from 19.6 pb~{-1} of p-pbar collisions recorded by the Collider Detector at Fermilab. These data are interpreted to determine the bquark fragmentation fractions f_u, f_d and f_s. We also determine the branching fractions for the decay modes B~+ --> J/psi K~+, B~+ --> J/psi K~*(892)~+, B~0 --> J/psi K~0, B~0 --> J/psi K~*(892)~0 and B_s~0 --> J/psi phi(1020). We discuss the implications of these measurements to B meson decay models.
Charge conjugated states are implied. FD is considered as a quark fragmentation fraction.
Using a silicon-microstrip detector array to identify secondary vertices, we have observed b→J/ψ→μ+μ− decays in 800GeV/c proton-gold interactions. The doubly differential cross section for J/ψ mesons originating from b-quark decays, assuming linear dependence on nucleon number, is d2σ/dxFdpT2=107±28±19[pb/(GeV/c)2]/nucleon at xF=0.05 and pT=1GeV/c. This measurement is compared to next-to-leading-order QCD predictions. The integrated b-quark production cross section, obtained by extrapolation over all xF and pT, is σ(pN→bb¯+X)=5.7±1.5±1.3 nb/nucleon.
All J/PSI(1S) are from B/BBAR decays. Cross section per nucleon was obtained with linear A-dependence.
Cross section per nucleon was obtained with linear A-dependence.
All J/PSI(1S) are from B/BBAR decays. Cross section per nucleon was obtained with linear A-dependence. Extrapolation in the XL=0.05 and PT=1 GEV bin.
We present a measurement of the b-quark cross section in 1.8 TeV p-p¯ collisions recorded with the Collider Detector at Fermilab using muonic b-quark decays. In the central rapidity region (‖yb‖<1.0), the cross section is 295±21±75 nb (59±14±15 nb) for pTb>21 GeV/c (29 GeV/c). Comparisons are made to previous measurements and next-to-leading order QCD calculations.
No description provided.
We present measurements of the bottom-quark production cross sections in pp¯ collisions at √s =1.8 TeV. From the inclusive electron production rate, we have determined the bottom-quark production cross sections to be 1010±270, 168±43, 37±10 nb for the rapidity range of ‖yb‖<1.0 and the transverse momentum ranges of pTb>15, 23, 32 GeV/c, respectively. In addition, from the associated electron-D0 production rate, we have determined the bottom-quark cross section to be 364±80(stat)±95(syst) nb for ‖yb‖<1.0 and pTb>19 GeV/c.
From the inclusive electron production rate.
From the associated electron-D0 production rate.
We have measured the ratio of the strong coupling constants α s for bottom quarks and light quarks at the Z 0 resonance, in order to test the flavour independence of the strong interaction. The coupling strength α s has been determined from the fraction of events with three jets, measured for a sample of all hardronic events, and for inclusive muon and electron events. The b purity is evaluated to be 22% for the first data set and 87% for the inclusive lepton sample. We find α s ( b ) α s ( udsc ) =1.00± 0.05 ( stat. )±0.06 ( syst. ) .
No description provided.
We summarize the results obtained in the UA1 experiment on the production of bottom quarks in proton-antiproton collisions at √ s =0.63 TeV. Independent muon data samples are used to determine the bottom quark production cross section in different transverse momentum ranges from 6 to 30 GeV. A recent theoretical calculation to O(α s 3 ) of the inclusive bottom quark transverse momentum spectrum in hadronic collisions shows reasonable agreement with the data. We extrapolate the integral P T distribution to P T =0 and in rapidity to estimate the total cross section forthe production of bottom quark pairs. Assuming the shape in P T and rapidity given by the O(α s 3 ) calcultaion, we obtain σ( p p→b b +X) = 10.2 ±3.3 μb .
No description provided.
B B production in π − -uranium interactions has been observed at 320 GeV beam energy looking at events with three muons in the final state. The cross section is found to be σ B B = 4.5±1.4±1.4 nb per nucleon (for a linear A -dependence) or σ B B = 17.6±5.5±5.5 nb per nucleon (assuming A 0.75 dependence). An estimate of x F distribution is given.
BEAUTY INCLUSIVE SPECTRA WAS ASSUMED TO BE E*D(SIG)/D(X)/D(PT**2) = EXP(-0.9*PT**2)*(1-ABS(X))**A. THE BEST FIT FOR A IS A = 2.5.
ASSUME A**.75 DEPENDENCE.
No description provided.
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