A measurement of b-quark fragmentation fractions in p¢p collisions at [centre of mass energy]=1.8 TeV

grantor: University of TorontoFragmentation is the process by which quarks and gluons organize themselves into hadrons. The fragmentation properties of the bottom quark cannot be predicted from fundamental principles and hence must be determined empirically. We investigate one such property, namely the flavour dependence of the fragmentation process for bottom quarks produced in 1.8-TeV proton-antiproton collisions. This flavour dependence is investigated by determining the 'B'-hadron production ratios. We use a sample of p&d1;p data corresponding to an integrated luminosity of 110 pb-1 and reconstruct the following semileptonic 'B'-hadron decays into electrons and charmed hadrons: B+[right arrow]e+neD&d1; 0X,B0[right arrow]e+n eD*-X , B0[right arrow]e+neD- X,B0s[right arrow]e +neD-s X and L&d1;0b [right arrow]e+neL- cX . With these data, we measure the ratios of fragmentation fractions fd/fu=&parl0;88± 21&parr0;%, fs/&parl0;fu+fd&parr0;= &parl0;21.5±7.1&parr0;%and fbaryon/&parl0;fu+fd&parr0; =&parl0;12.0±4.2&parr0;%. Assuming that these four hadrons saturate production of weakly-decaying ' B' hadrons, that is, that fu+fd+fs+fbaryon≡ 1 , we determine fu=&parl0;39.8±5.4&parr0; %, fd=&parl0;35.2±4.8&parr0; %, fs=&parl0;16.1±4.5&parr0; %and fbaryon=&parl0;9.0± 2.9&parr0;%. These results represent the first measurement of all four 'b'-quark fragmentation fractions in a single experiment. These fractions are in agreement both with previous phenomenological interpretations and with other experimental measurements.Ph.D