Measurement of the Ratio of Inclusive Cross Sections $\sigma (p\overline{p}\to Z+b\mathrm{\text{jet}})/\sigma (p\overline{p}\to Z+\mathrm{\text{jet}})$ at $\sqrt{s}=1.96\mathrm{TeV}$

Using the data collected with the D0 detector at $\sqrt{s}=1.96\mathrm{TeV}$, for integrated luminosities of about $180{\mathrm{pb}}^{-1}$, we have measured the ratio of inclusive cross sections for $p\overline{p}\to Z+b\mathrm{\text{jet}}$ to $p\overline{p}\to Z+\mathrm{\text{jet}}$ production. The inclusive $Z+b\mathrm{\text{−}}\mathrm{\text{jet}}$ reaction is an important background to searches for the Higgs boson in associated $ZH$ production at the Fermilab Tevatron collider. Our measurement is the first of its kind, and relies on the $Z\to e^{+}{e}^{-}$ and $Z\to {\mu }^{+}{\mu }^{-}$ modes. The combined measurement of the ratio yields $0.021\pm 0.005$ for hadronic jets with transverse momenta $p_T>20\mathrm{GeV}/c$ and pseudorapidities $|\eta |<2.5$, consistent with next-to-leading-order predictions of the standard model.

Figure 1

The $p_T$ distribution of taggable jets in dielectron and dimuon channels compared to $Z+\mathrm{\text{jet}}$ alpgen with pythia showering and full detector simulation (open histogram), and background (multijet for $ee$ channel and $b\overline{b}$ background for $\mu \mu$ channel) derived from data. The error bars on the data points are statistical. The prediction is normalized to the data, as described in the text.

Figure 2

(a) The $p_T$ spectrum for $b$-tagged jets. (b) Distribution in decay-length significance of secondary vertices in the transverse plane, without the requirement on decay-length significance. All error bars are statistical.