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Correlations between D and $${\overline D}$$ mesons produced in 500 GeV/cπ−-nucleon interactions (2000)

Aitala, E. M. ; Amato, S. ; Anjos, J. C. ; [et al.]

Springer

EPJ direct 1 (2000), S. 1-67

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ISSN: 1435-3725

Keywords: 12.38.-t ; 13.85.-t ; 13.87.Ce ; 13.87.Fh

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract We present a study of correlations between D and $${\overline D}$$ mesons produced in 500 GeV/cπ−-nucleon interactions, based on data from experiment E791 at Fermilab. We have fully reconstructed 791 ± 44 charm meson pairs to study correlations between the transverse and longitudinal momenta of the two D mesons and the relative production rates for different types of D meson pairs. We see slight correlations between the longitudinal momenta of the D and the $${\bar D}$$ , and significant correlations between the azimuthal angle of the D and the $${\bar D}$$ . The experimental distributions are compared to a next-to-leading-order QCD calculation and to predictions of the PYTHIA/JETSET Monte Carlo event generator. We observe less correlation between transverse momenta and different correlations between longitudinal momenta than these models predict for the default values of the model parameters. Better agreement between data and theory might be achieved by tuning the model parameters or by adding higher order perturbative terms, thus contributing to a better understanding of charm production. The relative production rates for the four sets of charm pairs, $$D^0{{\overline D}^0}, D^0 D^{-}, D^+{{\overline D}^0}, D^+ D^{-}$$ as calculated in the PYTHIA/JETSET event generator with the default parameters, agree with data as far as the relative ordering, but predict too many $$D^+ {{\overline D}^0}$$ pairs and too few $$D^+ D^{-}$$ pairs.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s101059900c0004

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Studies on sulfur vulcanization of natural rubber accelerated with diphenylguanidine both in presence and absence of dicumyl peroxide (1971)

Manik, S. P. ; Banerjee, S.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 15 (1971), S. 1341-1355

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ISSN: 0021-8995

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: Diphenylguanidine acceleration of sulfuration of natural rubber both in the presence and absence of dicumyl peroxide (DCP) has been studied. DPG enhances the rate of decomposition of DCP, and the crosslinking maxima due to DCP are lowered by DPG to some extent, which increases with the concentration up to a limiting value. The rate of sulfur decrease is very high and is dependent on DPG concentration but practically independent of the presence of ZnO and stearic acid. It is observed that with constant level of DCP and sulfur, crosslinking increases with the increase of DPG concentration and finally becomes additive when the molar proportion of DPG: S8 approximately equals 1:1. In presence of ZnO and stearic acid, with each increment of DCP concentration crosslinking is retarded for both systems. Mechanisms have been suggested in terms of polar and radical process.

Additional Material: 5 Ill.