Search for second-generation scalar leptoquarks in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$

Results on a search for pair production of second-generation scalar leptoquark in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ are reported. The data analyzed were collected by the CDF detector during the 2002–2003 Tevatron Run II and correspond to an integrated luminosity of $198{\mathrm{pb}}^{-1}$. Leptoquarks (LQ) are sought through their decay into (charged) leptons and quarks, with final state signatures represented by two muons and jets and one muon, large transverse missing energy and jets. We observe no evidence for LQ production and derive 95% C.L. upper limits on the LQ production cross sections as well as lower limits on their mass as a function of $\beta$, where $\beta$ is the branching fraction for $\mathrm{LQ}\to \mu q$.

Figure 1

Graphical representation of the last two topological cuts applied in the $\mu \mu jj$ analysis as observed on MC events. The discrimination between SM background and LQ signal is evident.

Figure 2

Final mass distributions (see text) of the surviving events before the mass limit cut compared to the signal distribution for $M_{\mathrm{LQ}}=180\mathrm{GeV}/{\mathrm{c}}^2$.

Figure 3

95% C.L. limit on the experimental cross section times branching ratio as a function of the LQ mass for the $\mu \nu jj$ and $\mu \mu jj$channel. The NLO theoretical cross section is plotted for different values of the renormalization scale. Mass limits of $170\mathrm{GeV}/{\mathrm{c}}^2$ and $224\mathrm{GeV}/{\mathrm{c}}^2$ respectively are obtained.

Figure 4

Leptoquark mass exclusion regions at 95% C.L. as function of $\mathrm{Br}(\mathrm{LQ}\to \mu \mathrm{q})$.