0000000000223785
AUTHOR
M. A. Sanchis
Measurement of charmed-particle lifetimes and decay branching ratios
The lifetimes of charmed hadrons photoproduced in nuclear emulsion have been computed from a practically background-free sample of 44 neutral particle decays and 42 charged-particle decays including 27D±, 11Λc+, 1Ds+ and 3 ambiguous decays. The values obtained are τ(D0, bar D0) = (3.6-0.8+1.2 ± 0.7) 10-13 s, τ(D±) = (5.0-1.0+1.5 ± 1.9) 10-13 s, τ(Λc+) = = (2.3-0.6+0.9 ± 0.4) 10-13 s. Branching ratios of various decay topologies were also obtained.
Nuclear Interactions of 400 GeV Protons in Emulsion
Abstract We report on 400 GeV proton-emulsion nucleus reactions and compare the results to hadron-nucleus reactions at smaller energies. In particular we present results on the emission of fast target protons (essentially grey track particles) and on their correlation with the number of collisions inside the nucleus, ν, with the number of charged evaporated particles (essentially black track particles) and with the number of pions produced (essentially shower particles). We observe that the main features of the 200–400 GeV data are very similar. However, we find that the mean shower-particle multiplicity at 400 GeV is essentially higher than expected from the simple independent particle mod…
A Comment on form-factor mass singularities in flavor changing neutral currents
Flavor-changing effective verticesq l q h V 0, whereV 0 represents a neutral gauge boson (γ,Z 0,g), involving a heavy external quark, are discussed within the standard model at one-loop level and second-order approximation in external momenta and masses: the logarithmic singular terms in the form factors at vanishing mass of the internal quark in the loop have to be replaced by pieces coming from next order in external momenta. Implications in theb→d+X penguin transitions are commented.
Cross sections and some features of charm photoproduction at gamma energies of 20-70 GeV
Abstract We report some results on charm photoproduction at γ energies ranging from 20 to 70 GeV. 36 events with pairs of charmed particles have been found in emulsions. The computed total cross section is (230±57)nb/nucleon. Frequencies of different production channels and some distributions are presented and compared with the predictions from a photon-gluon fusion model with string fragmentation.
Measurement of the Lifetime of Neutral Charmed Mesons
Abstract The lifetime of neutral charmed particles photoproduced in emulsion has been measured. The lifetime value presented here was obtained from a sample of 22D 0 mesons, 18 of which have their charmed partner seen in emulsion. The sample is essentially background-free. The result obtained is τ D 0 =(2.11 +1.21 -0.63 )×10 13 s The D 0 mass derived from 8 3C events is m D 0 = 1856 ± 36 MeV/ c 2 .
Charged charmed particle lifetime
Abstract We present the lifetime values obtained for D ± and Λ c + , photoproduced in nuclear emulsion in the WA58 experiment. In photohadronic interactions, pairs of charmed particles are produced. Out of 20 charged charmed particles used for lifetime evaluation, 17 have their charmed partner seen emulsion, being then essentially free from any background. The values of the lifetime are τ D ± = (3.91 −1.25 +2.35 ) × 10 −13 s, τ Λ c + = (2.22 −0.75 +1.34 ) × 10 −13 s.
Two-particle correlations in 400 GeV proton-nucleus interactions
Two-particle inclusive correlations are studied by means of the two-particle rapidity correlation function. The data for the analysis come from an exposure of emulsion plates to a 400 GeV proton beam at FNAL. Predominant short-range correlations among shower particles are found, but this does not allow to exclude some long-range correlation behaviour, in agreement with the results obtained in lower-energy experiments.