Search for Pair Production of Scalar Bottom Quarks in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

A search for direct production of scalar bottom quarks ($\tilde{b}$) is performed with $310{\mathrm{pb}}^{-1}$ of data collected by the D0 experiment in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ at the Fermilab Tevatron Collider. The topology analyzed consists of two $b$ jets and an imbalance in transverse momentum due to undetected neutralinos (${\tilde{\chi }}_1^0$), with ${\tilde{\chi }}_1^0$ assumed to be the lightest supersymmetric particle. We find the data consistent with standard model expectations, and set a 95% C.L. exclusion domain in the ($m_{\tilde{b}}$, $m_{{\tilde{\chi }}_1^0}$) mass plane, improving significantly upon the results from run I of the Tevatron.

Figure 1

Distribution in ${\mathrm{E̸}}_T$ after applying all criteria, except ${\mathrm{E̸}}_T>60\mathrm{GeV}$ ($\mathbf{C}\mathbf{1}$). The dark shaded area corresponds to the SM simulation. A fit by an exponential to ${\mathrm{E̸}}_T<60\mathrm{GeV}$, after subtraction of the contributions from the SM, shown in the figure insert, is used to estimate the instrumental background.

Figure 2

Excluded regions at the 95% C.L. in the sbottom and neutralino mass plane. The new region excluded by this analysis is shown in dark shading. The dashed line corresponds to the expected limit. Regions excluded by previous experiments are also displayed in the figure [5].