Search for scalar leptoquark pairs decaying to $\nu \overline{\nu }q\overline{q}$ in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We report on a search for the pair production of scalar leptoquarks (LQ), using $191{\mathrm{pb}}^{-1}$ of proton-antiproton collision data recorded by the CDF experiment during Run II of the Tevatron. The leptoquarks are sought via their decay into a neutrino and quark yielding missing transverse energy and several jets of large transverse energy. No evidence for LQ production is observed, and limits are set on $\sigma (p\overline{p}\to \mathrm{LQ}\overline{\mathrm{LQ}}X\to \nu \overline{\nu }q\overline{q}X)$. Using a next-to-leading order theoretical prediction of the cross section for LQ production, we exclude first-generation LQ in the mass interval 78 to $117\mathrm{GeV}/c^2$ at the 95% confidence level for $BR(\mathrm{LQ}\to \nu q)=100\%$.

Figure 1

The ${\mathrm{E̸}}_T$ distribution in the leptoquark signal region for data (solid points) compared to SM background (shaded histograms). Also shown is the expected distribution arising from leptoquark production and decay at a mass of $115\mathrm{GeV}/c^2$ (hatched histogram).

Figure 2

The upper limit on the cross section times squared branching ratio for scalar leptoquark production in the jets and ${\mathrm{E̸}}_T$ topology. Also shown is the NLO cross section for $\beta =0$ for 2 choices of the factorization/renormalization scale: $\mu =m_{{\mathrm{LQ}}_1}$, $\mu =2m_{{\mathrm{LQ}}_1}$.