Search for Scalar Bottom Quarks from Gluino Decays in $\overline{p}p$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We searched for scalar bottom quarks in $156{\mathrm{pb}}^{-1}$ of $\overline{p}p$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ recorded by the Collider Detector at Fermilab II experiment at the Tevatron. Scalar bottom quarks can be produced from gluino decays in $R$-parity conserving models of supersymmetry when the mass of the gluino exceeds that of the scalar bottom quark. Then, a scalar bottom quark can decay into a bottom quark and a neutralino. To search for this scenario, we investigated events with large missing transverse energy and at least three jets, two or more of which were identified as containing a secondary vertex from the hadronization of $b$ quarks. We found four candidate events, where $2.6\pm 0.7$ are expected from standard model processes, and placed 95% confidence level lower limits on gluino and scalar bottom quark masses of up to 280 and $240\mathrm{GeV}/c^2$, respectively.

Figure 1

Distributions of $\Delta \varphi$ (${\mathrm{E̸}}_T$, 1st jet), the azimuthal angle between the ${\mathrm{E̸}}_T$ and the highest $E_T$ jet in the event, if it is $b$-tagged in control region C0 (left), C1 (middle), and C2 (right).

Figure 2

${\mathrm{E̸}}_T$ spectrum after vetoing events with high-$p_T$ isolated leptons, for single $b$-tagged events (left) and double $b$-tagged events (right).

Figure 3

The 95% C.L. cross section upper limit as a function of the gluino mass for a $60\mathrm{GeV}/c^2$ mass difference between the gluino and sbottom (left). The 95% C.L. limit curve in the $m(\tilde{g})\mathrm{\text{−}}m({\tilde{b}}_1)$ plane for inclusive double $b$-tagged events (right).