A measurement of the ratio of inclusive cross sections $\sigma (p\bar{p}\to Z+b\mathrm{j}\mathrm{e}\mathrm{t})\mathrm{/}\sigma (p\bar{p}\to Z+\mathrm{j}\mathrm{e}\mathrm{t})$ at $\sqrt{s}=1.96$ TeV

The ratio of the cross section for $p\bar{p}$ interactions producing a $Z$ boson and at least one $b$ quark jet to the inclusive $Z+\mathrm{j}\mathrm{e}\mathrm{t}$ cross section is measured using $4.2{\mathrm{f}\mathrm{b}}^{-1}$ of $p\bar{p}$ collisions collected with the \dzero\ detector at the Fermilab Tevatron collider at $\sqrt{s}=1.96$ TeV. The $Z\to {\mathrm{\ell }}^{+}{\mathrm{\ell }}^{-}$ candidate events with at least one $b$ jet are discriminated from $Z+$ charm and light jet(s) events by a novel technique that exploits the properties of the tracks associated to the jet. The measured ratio is $0.0193\pm 0.0027$ for events having a jet with transverse momentum $\text{pt}>20\text{GeV}$ and pseudorapidity $\mathrm{\mid }\eta \mathrm{\mid }\le 2.5$, which is the most precise to date and is consistent with theoretical predictions.