Inclusive electron production from heavy quarks in e+e− annihilation at 34.6 GeV center of mass energy

The production of electrons by bottom and charm hadrons has been studied in e⁺e^? annihilation at 34.6 GeV center of mass energy. It is observed that the b quark fragmentation function is peaked at large values of the scaling variable z with 〈z_b〉 = 0.84^{+0.15 + 0.15}_{?0.10 ? 0.11}. For c quarks 〈z_c〉 = 0.57^{+0.10 + 0.05}_{?0.09 ? 0.06} is observed. A forward-backward charge asymmetry of A = ?0.25 ± 0.22 was measured in b production.     

Dichlorocarbene Addition to

In contrast to the terminal phosphinidene complex PhPW(CO)(5) (2), which adds to [5]metacyclophane (1) in a 1,4-fashion, dichlorocarbene preferentially adds in a 1,2-fashion to the formal "anti-Bredt" type double bond of the aromatic ring of 1 to afford the norcaradiene 11b, which immediately rearranges to the bridged cycloheptatriene 12b and further by a [1,5] sigmatropic chlorine migration to the isomeric 13b as the first observable product. More slowly, the latter isomerizes via a dissociative mechanism to give 15b. A computational study supports the notion that the [1,5] chlorine migration in the rearrangement 12b --> 13b, for which an activation barrier of 70.2 kJ mol(-)(1) was calculated, is essentially concerted with minor charge separation. In contrast, the analogous [1,5] chlorine migration in the flat model compound 7,7-dichlorocycloheptatriene (12a) displays features of a dissociative pathway.     

Experimental test of the flavor independence of the quark-gluon coupling constant

Reconstruction of charged D¹'s produced inclusively in e⁺e?. annihilation at CM energies near 34.4 GeV is accomplished in the decay modes $\text{D}\text{1}{}^{\mathrm{+}}\text{→}\text{D}{}^0\text{π}{}^{\mathrm{+}}\text{→}\text{K}{}^{\mathrm{?}}\text{gp}{}^{\mathrm{+}}\text{π}{}^0\text{π}{}^{\mathrm{+}}\text{and}\text{D}\text{1}{}^{\mathrm{+}}\text{→}\text{D}{}^0\text{π}{}^{\mathrm{+}}\text{→}\text{K}{}^{\mathrm{?}}\text{gp}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{+}}$ and their charge conjugates. Using these and previously reported $\text{D}\text{1}{}^{\mathrm{+}}\text{→}\text{D}{}^0\text{π}{}^{\mathrm{+}}\text{→}\text{K}{}^{\mathrm{?}}\text{gp}{}^{\mathrm{+}}\text{π}{}^{\mathrm{+}}\text{and}\text{D}\text{1}{}^{\mathrm{+}}\text{→}\text{D}{}^0\text{π}{}^{\mathrm{+}}\text{→}\text{K}{}^{\mathrm{?}}\text{gp}{}^{\mathrm{+}}\text{π}{}^{\mathrm{+}}\text{+}\text{missing}\text{π}{}^0$ channels we present evidence for hard gluon bremsstrahlung from charm quarks and show that the ratio of the quark-gluon coupling constant of charm quarks to the coupling constant obtained in the average hadronic event, $\text{α}{}_{\mathrm{<mtext>s</mtext>}}{}^{\mathrm{<mtext>c</mtext>}}\text{α}{}_{\mathrm{rms}}\text{= 100 ± 0.20 ± 1.20}$. Our result provides evidence that the quark-gluon coupling constant is independent of flavor.     

Adsorption and Desorption of Triton X-100 in Polystyrene Particles with Different Functionality

An experimental desorption study of Triton X-100 from latices with different functionality is presented. Two different strategies to follow the desorption experiment have been used: first, a discontinuous method based on the wash step (centrifugation-removal-redispersion); and second, a continuous method based on the replacement of the disperse media. The desorption results show that in all cases a residual amount of Triton X-100 remains adsorbed, indicating irreversibility of the surfactant adsorption. Finally, the effect of desorption on the colloidal stability of one type of latex-surfactant complex has been analyzed. Copyright 2000 Academic Press.