We have searched for the decay D 0 → μ + μ − among 1.25 × 10 5 μ + μ − pairs produced by 350 GeV/ c π − particles interacting in copper and tungsten targets. Using a high-resolution silicon-microstrip detector followed by a large-acceptance magnetic spectrometer and a muon filter we are able to discriminate between prompt and non-prompt muons and to measure dimuon masses. No candidate compatible with a D 0 → μ + μ − decay has been found, allowing us to set an upper limit on the branching fraction B( D 0 → μ + μ − ) of 7.6 × 10 −6 at the 90% confidence level.
NUCLEUS OF TARGET=CU+WT.
We measure the relative cross sections for D mesons produced in interactions of π− and π+ beams with targets of Be, Cu, Al, and W. The measurement is based on 1400 fully reconstructed decays of the types D0→K−π+, D+→K−π+π+, and charge conjugates. We find that the cross section for the production of both neutral and charged D’s by either π− or π+ is well fitted by the form Aα where A is the atomic mass and α=1.00±0.05±0.02, where the errors are statistical and systematic, respectively. There is no significant dependence of α on the transverse or longitudinal momentum of the D meson or on the charge of either the incident pion or the produced D mesons.
No description provided.
We measure the differential cross section with respect to Feynman-x (xF) and transverse momentum (PT) for charm meson production using targets of Be, Al, Cu, and W. In the range 0.1<xF<0.7, dσ/dxF is well fit by the form (1-xF)n with n=3.9±0.3. The difference between n values for D− and D+ is 1.1±0.7. However, we find an asymmetry of 0.18±0.06 favoring the production of D− compared to D+. In the lower PT range, <2 GeV, dσ/dPT2 is well fit by the form exp(-b×PT2) with b=1.03±0.06 GeV−2, while in the higher PT range, 0.8 to 3.6 GeV, it is well fit by the form exp(-b’×PT) with b’=2.76±0.08 GeV−1. The shape of the differential cross section has no significant dependence on atomic mass of the target material.
No description provided.
Results of fit to DSIG/DXL distribution of the form (1-XL)**POWER in the XL range 0.1 to 0.7. Statistical errors only. Systematic errors are small in comparison.
Results of fit to DSIG/DPT**2 distribution of the form exp(-POWER*PT**2) in the PT**2 range 0.0 to 4.0 GeV**2.
Charmed mesons, produced on silicon, copper and tungsten by 340 GeV π - , have been identified as peaks in invariant mass distributions. The comparison of the yields of charmed particles originating from interactions in Si, Cu and W allows the mass number dependence of the charm hadroproduction cross section to be measured. Assuming the usual parametrization σ c = σ 0 A α , we find α =0.92±0.06 for charmed mesons with 〈 x F 〉=0.24. We do not find any decrease of α with increasing x F in contrast to the case of the production of particles containing only light quarks.
SI, CU, and WT are used. The cross section is parametrized as : SIG = CONST*A**POWER.
Results are presented on the production characteristics of charmed particles obtained from the WA75 emulsion hybrid experiment. The events, selected by the presence of a muon with a high momentum transverse to the beam direction, were located and analysed in nuclear emulsions. Inclusive and correlation properties are systematically compared with the lowest-order QCD calculations for DD hadroproduction. Results concerning the correlation properties indicate some contribution from next-to-leading order [O(α_S^3)] subprocesses.
459 DECAYS: 119 D0, 119 DBAR0, 115 D+, 106 D-.
177 PAIRS: 38 D0 DBAR0, 46 D0 D-, 45 D+ DBAR0, 48 D+ D-.
120 PAIRS: 38 D0 DBAR0, 31 D0 D-, 32 D+ DBAR0, 19 D+ D-.
None
AUTHORS FIT D2(SIG)/D(XL)/D(PT**2) BY (1-XL)**POWER*EXP(-SLOPE*PT**2).
AUTHORS FIT D2(SIG)/D(XL)/D(PT**2) BY (1-XL)**POWER*EXP(-SLOPE*PT**2).
AUTHORS FIT D2(SIG)/D(XL)/D(PT**2) BY (1-XL)**POWER*EXP(-SLOPE*PT**2).
We have measured the differential and total cross sections ofD meson production in 200 GeV π−-beryllium interactions, using a sample of 48 fully reconstructed and nearly background-freeD mesons in the decay channelsK∓π±,K∓π±π± andK∓π∓π±π±. A single electron trigger has been used to select events containing a pair of charmed particles. A vertex telescope of 6 silison microstrip detectors allowed the reconstruction of tracks of charged secondaries and the reconstruction of primary and decay vertices with high precision. The ratio of branching fractions for\(\mathop {D^0 }\limits^{( - )}\to K^ \mp\pi ^ \pm\) to\(\mathop {D^0 }\limits^{( - )}\to K^ \mp\pi ^ \mp\pi ^ \pm\pi ^ \pm\), and an upper limit for\(D^0- \bar D^0 \) mixing are presented.
'leading' D-mesons, i.e. D-mesons, containing quarks, from PI- beam. Also AD0-mesons from. D*- decays.
'non-leading' D-mesons.
No description provided.