Measurement of the ratio of differential cross sections $\sigma (p\overline{p}\to Z\mathbf{+}b\mathrm{\text{jet}})/\sigma (p\overline{p}\to Z\mathbf{+}\mathrm{\text{jet}})$ in $p\overline{p}$ collisions at $\sqrt{s}\mathbf{=}1.96\mathrm{TeV}$

We measure the ratio of cross sections, $\sigma (p\overline{p}\to Z+b\mathrm{\text{jet}})/\sigma (p\overline{p}\to Z+\mathrm{\text{jet}})$, for associated production of a $Z$ boson with at least one jet. The ratio is also measured as a function of the $Z$ boson transverse momentum, jet transverse momentum, jet pseudorapidity, and the azimuthal angle between the $Z$ boson with respect to the highest $p_T$ $b$ tagged jet. These measurements use data collected by the D0 experiment in Run II of Fermilab’s Tevatron $p\overline{p}$ Collider at a center-of-mass energy of 1.96 TeV, and correspond to an integrated luminosity of $9.7{\mathrm{fb}}^{-1}$. The results are compared to predictions from next-to-leading order calculations and various Monte Carlo event generators.

Figure 1

The leading jet $p_T$ in the (a) $Z\to ee$ and (b) $Z\to \mu \mu$ channels for data and background in events with a $Z$ boson candidate and at least one jet before $b$ tagging is applied.

Figure 2

(a) The probability densities of the $D_{\mathrm{MJL}}$ discriminant for $b$, $c$, and light jets passing the $b$-tagging requirements, normalized to unity. These templates are taken from MC simulations. (b) The $D_{\mathrm{MJL}}$ discriminant distribution of events in the combined sample. The distributions of the $b$, $c$, and light jets are normalized by the fractions found from the fit.

Figure 3

Ratios of the differential cross sections (a) $p_T^{\mathrm{jet}}$ (b) $p_T^Z$ (c) ${\eta }^{\mathrm{jet}}$ and (d) $\Delta {\phi }_{Z,\mathrm{jet}}$. The uncertainties on the data include statistical and systematic uncertainties added in quadrature. The data are compared to the prediction from alpgen, sherpa, and the mcfm NLO calculation, where the band represents the variation of the renormalization and factorization scales up and down by a factor of 2. Bin centers are chosen using the prescription found in Ref. [27].