24 research outputs found
The radiative decay width: a measurement at 200 GeV
No full textThe ρ- radiative decay width has been measured by studying the production of ρ- via the Primakoff effect by 200 GeV incident π- on Cu and Pb targets. This width was obtained by fitting the measured dσ/dt for ρ production with the theoretical coherent differential cross section including both the electromagnetic and strong contributions. The measured radiative width value is 81 +/- 4 +/- 4 keV: it is consistent with the ratio Γ(ρ --> πγ)/Γ(ω --> πγ) ~ case:1/9 as expected from the vector dominance and the quark model
Measurement of the pion form factor in the time-like region for values between 0.1 (GeV/c) and 0.18 (GeV/c)
No full textThe EM form factor of the pion has been studied in the time-like region by measuring sigma(e+e- -> pi+pi-) normalized to sigma(e+e- -> mu+mu-). Results have been obtained for q2 down to the physical threshold
A measurement of lifetime
No full textA measurement of the lifetime of D0-mesons photoproduced coherently off a germanium target is presented. Signals have been observed for the production of D0bar D into several channels and for D*+ -> D0 pi+. A sample of 58 D0 decays gives a lifetime of (3.4−0.5/+0.6 +/- 0.3) 10^-13 s
A Ge-Si active target for the measurement of short lifetimes
No full textA new Ge-Si active target is presently used in the NA1 experiment at CERN to study photoproduction of charmed particles and to measure their lifetimes. Some general comments on the active target technique are made
Photoproduction of D Mesons
No full textPreliminary results are presented using the Wide Band photon beam at Fermilab
to measure the cross-section of D*+/- and D+/- photoproduction on a Be target over the
photon enera rsngs from 100 GeV to 350 GeV. Preliminary results are also presented
on the xF and pT2 distributions and the ratios of D0/D*+ and D*-/D*+. The energy
dependence of the total open charm cross-section of photoproduction was compared
with the predictions by the photon-gluon fusion model and a higher order QCD radiative
correction based on perturbative QCD. The prediction by the QCD radiative
correction with Mc = 1.5GeV agrees well with the observed data within the theoretical
uncertainties of the QCD parameters
Some lifetimes and branching ratios for charmed hadrons produced in the Fermilab wide band photon beam.
No full textPreliminary values are presented for lifelimes of the Lambdac+ decaying into pK-pi+ and Ds decaying into fi pion. Also presented are preliminary results on samples of
D0 --> K0bar K+ K- , including D0 --> K0bar fi, and D0 --> K0bar pi+pi- decays. The data are
from the first run of Fermilab experiment E687 using the Fermilab Wide-Band Photon
Spectrometer. Our lifetime values are (0.20 +/- 0.03 +/- 0.03) ps for the Lambdac+ and
(0.50 +/- 0.06 +/- 0.03) ps for the Ds+ . We find preliminary values for the branching ratios
B(D0 --> K0bar K+K- )/B(D0 --> K0bar pi+pi- ) and B(D0 --> K0bar fi )/B(D0 --> K0bar pi+ pi- )of
0.20 +/- 0.06 and 0.16 +/- 0.06, respectively; only statistical errors are quoted. Further work is in progress
Study of D0→Ks0 π+π− and D0→Ks0 K+K− in high energy photoproduction
No full textAnalysis of the resonant and non-resonant branching fractions for the decays D0→KS0π+π−and D0→KS0K+K− is presented. For the D0→KS0π+π− decay, a fit to the observed Dalitz plot was performed to determine the complex amplitudes of the sub-component modes. For the D0→KS0K+K− decay, measurements of the branching ratios D0→KS0K+K− (inclusive), D0→KS0φ, and D0→KS0(K+K−)non-φ relative to the D0→KS0π+π− mode are reported. The data were collected by the Fermilab high energy photoproduction experiment E687
photoproduction and lifetime measurement
No full textA measurement of the lifetime of the Lambda c baryon photoproduced coherently off a Germanium-Silicon target is presented. A signal of Lambda_c -> Delta K*-> p k pi pi0 has been observed and the two different decay diagrams for this process are compared. A sample of 9 Lambda_c decays gives a lifetime of (1.1-0.4+0.8)x10(-13)s
