The hadronic production of charmed states was studied in a two-arm spectrometer using a 205-GeV/c negative-pion beam incident upon a beryllium target. One arm, filled with dense absorber, triggered the detectors upon the passage of a muon with a moderate transverse momentum and a total momentum of at least 4 GeV/c. The other arm was an open-geometry magnetic spectrometer which had both neutral- and charged-particle identification capabilities. The apparatus, the data, and an invariant-mass-plot search for evidence of charmed-meson production through several charged-particle decay modes are described. The Kπ, Kππ, and Kπππ mass plots fail to reveal significant D-meson signals. Based upon the Kπ mass plots, the 95%-confidence upper limit on the DD¯ production cross section is found to be less than 51 μb per nucleon for the production models tested. A search for evidence of charged-D* production yields 30±16 combinations above background in association with the expected trigger muon charge. Interpreted as a D* signal, this excess corresponds to a model-dependent inclusive DD¯ production cross section of 34±18−9+14 μb per nucleon. Model-dependent upper limits on the ratio of the F to D cross sections are also presented.
Uncorrelated model for charmed mesons production.
'Correlated' model for pair of charmed mesons production.
Uncorrelated model for D/S+- mesons production.
A search for charm production in the coherent diffractive dissociation reaction pSi→XSi was carried out for the modes D 0 → K − π + , D 0 → K − π + π + π − , and D + → K − π + π + . No charm signals were observed, and the 90% confidence level upper limit for coherent charm pair production was determined to be 26 μ b per silicon nucleus. The results are interpreted as an upper limit of 0.2% on the amount of intrinsic charm in the proton.
90 pct CL upper limits.
We present total and differential cross sections for charm mesons produced in 600 GeV/ c π - emulsion interactions. Fits to d 2 σ / dx F dp T 2 ∞ (1−| x F |) n exp (- bp T 2 ) for 676 electronically reconstructed D mesons with x F >0 give n =4.25±0.24 ( stat .)±0.23 ( syst .) and b =0.76±0.03±0.03 ( GeV / c ) -2 . The total inclusive D + and D 0 cross sections are σ ( π - N → D ± ; x F >0) = 8.66±0.46±1.96 μb nucleon and σ(π - N→D 0 D 0 ; x F >0)=22.05±1.37±4.82μb nucleonk, where a linear dependence on the mean atomic weight of the target is assumed. These results are compared to next-to-leading order QCD predictions.
Linear A-dependence. Different modes of the charm mesons detection were used (see text for detail). The differential cross section is fitted by the equation : D2(SIG)/D(XL)/D(PT**2) = CONST*(1-XL)**POWER*EXP(-SLOPE*PT**2).
We report results on D 0 and D + production in proton-emulsion interactions at s =38.7 GeV. A fit to the form (1−| x F |) n exp (−bp 2 T ) yields n=6.9 +1.9 −1.8 and b=0.84 +0.10 −0.08 (GeV/ c ) −2 . The total inclusive cross section, is assuming linear A dependence, is measured to be 38±3(stat.) ±13 (sys.) μ b for the D 0 and 38±9±14 μ b for the D + . A comparison of these results with previous measurements indicates that nuclear effects do not strongly influence charm production. The predictions of QCD are in good agreement with our data.
The differential cross section is fitted by the equation : D2(SIG)/D(XL)/D(PT**2) = CONST*(1-XL)**POWER*EXP(-SLOPE*PT**2).
The differential cross section is fitted by the equation : D2(SIG)/D(XL)/D(PT**2) = CONST*(1-XL)**POWER*EXP(-SLOPE*PT**2).
Linear A-dependence. Different modes of the charm mesons detection were used (see text for detail).
Hadronic charm production was investigated with a two-arm magnetic spectrometer. The experiment was triggered on muons from the semileptonic decay of charm particles in one arm while reconstructing the mass of the associatively produced partners in the other arm. An excess of 153±46 combinations above background for the neutral D→Kπ mode was observed. This corresponds to a model-dependent DD¯ production cross section of 41±12+15−11 μb per nucleon, where the first uncertainty is statistical and the second is systematic.
Cross sections based on (1-ABS(XF))**3 production model.
Cross section based on (1-ABS(XF))**3 production model.
The inclusive cross section for charged-D* production by 205-GeV/c π− mesons incident on a beryllium target was measured with a two-arm spectrometer triggered by prompt muons. Using the mass-difference technique often employed in D* studies, a signal of 31±11 charged D*’s was isolated; it includes contributions from both the D*+ and D*− charged modes in correlation with triggering muons of the proper charge. This corresponds to an inclusive charged-D* production cross section of 220±77−57+77 μb per Be nucleus or 24±9−6+9 μb per nucleon when the cross section is scaled linearly with atomic mass number. The first error is statistical and the second is systematic.
No description provided.
Differential cross sections have been measured for nucleon-isobar production and elastic scattering in p−p interactions from 6.2 to 29.7 GeVc in the laboratory angle range 8<θsc<265 mrad. N*' s at 1236, 1410, 1500, 1690, and 2190 MeV were observed. Computer fits to the mass spectra under varying assumptions of resonance and background shapes show that conclusions on t and s dependence are only slightly affected despite typical variations in absolute normalization of ± 35%. Logarithmic t slopes in the small- |t| range are ∼15 (GeVc)−2 for the N*(1410), ∼5 (GeVc)−2 for the N*'s at 1500, 1690, and 2190 MeV, and ∼9 (GeVc)−2 for elastic scattering. Also for the small- |t| data, cross sections for N*'s at 1410, 1500, 1690, and 2190 MeV and for elastic scattering vary only slightly with Pinc consistent with the dominance of Pomeranchuk exchange and with diffraction dissociation. A fit of N*(1690) total cross sections to the form σ∝P−n gives n=0.34±0.06, while for elastic scattering n=0.20±0.05. For the N*(1690) the effective Regge trajectory has the slope αeff′(0)=0.38±0.17. When compared with N* production in π−, K−, and p¯ beams these data also agree with approximate factorization of the Pomeranchuk trajectory. N*(1236) cross sections are consistent with other measurements at similar momenta. For −t>1 (GeVc)−2, elastic scattering cross sections decrease approximately as Pinc−2, and they and N*(1500)− and N*(1690)− production cross sections have t slopes consistent with 1.6 (GeVc)−2.
ERROR IS 50 PCT.
The magnitude of |f21(0)|, the coherent K0 regeneration amplitude in Cu, has been measured for K momenta from 600 to 1400 MeVc. Results are compared with predictions of an optical model using forward dispersion relation predictions for real parts of kaon-nucleon scattering amplitudes.
No description provided.
We have observed $23.2 \pm 6.0_{-0.9}^{+1.0}$ purely-leptonic decays of $D_s^+ -> \mu^+ \nu_\mu$ from a sample of muonic one prong decay events detected in the emulsion target of Fermilab experiment E653. Using the $D_s^+ -> \phi \mu^+ \nu_\mu$ yield measured previously in this experiment, we obtain $B(D_s^+ --> \mu^+ \nu_\mu) / B(D_s^+ --> \phi \mu^+ \nu_\mu) =0.16 \pm 0.06 \pm 0.03$. In addition, we extract the decay constant $f_{D_s}=194 \pm 35 \pm 20 \pm 14 MeV$.
No description provided.
Employing a neutral kaon beam at the Argonne Zero Gradient Synchrotron, a high-resolution magnetic spectrometer, and a neutron detector, differential cross sections have been obtained in the forward direction [0.045<|t|<0.18 (GeV/c)2] for the reaction KL0p→K+n. Previous studies of the time-reversed process in deuterium, K+d→K0p(p), have not yielded direct cross-section measurements in the forward direction because there is an inhibition of the non-spin-flip process in deuterium due to the Pauli exclusion principle. Nevertheless, our data are in agreement with the extracted free-neutron cross sections of deuterium studies as determined from the impulse and closure approximations.
No description provided.
No description provided.
No description provided.
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