Measurement ofb-Quark Fragmentation Fractions inpp¯Collisions ats=1.8TeV

We have studied the production of $B$ hadrons in 1.8-TeV $p\overline{p}$ collisions. We present measurements of the fragmentation fractions, $f_u$, $f_d$, $f_s$, and $f_{\mathrm{baryon}}$, of produced $b$ quarks that yield $B^{+}$, $B^0$, $B_s^0$, and ${\overline{\Lambda }}_b^0$ hadrons. Reconstruction of five electron-charm final states yields $f_s/\left(f_u{+f}_d\right)=0.213\mathrm{}\pm 0.068$ and $f_{\mathrm{baryon}}/\left(f_u{+f}_d\right)=0.118\mathrm{}\pm 0.042$, assuming $f_u{=f}_d$. If all $B$ hadrons produced in $p\overline{p}$ collisions cascade to one of these four hadrons, we determine $f_u{=f}_d=0.375\mathrm{}\pm 0.023$, $f_s=0.160\mathrm{}\pm 0.044$, and $f_{\mathrm{baryon}}=0.090\mathrm{}\pm 0.029$. If we do not assume $f_u{=f}_d$, we find $f_d/f_u=0.84\mathrm{}\pm 0.16$.