Searches for Leptoquark production in p p-bar collisions at the D0 experiment

We report on searches for the production of scalar and vector leptoquarks in $p\bar{p}$ collisions at the Tevatron collider, which are based on integrated luminosities of up to 2.5\,fb$^{-1}$ collected with the D0 detector. Leptoquarks, which are predicted by several extensions of the Standard Model, are hypothetical particles carrying both lepton and quark flavors. At hadron colliders they can either be pair-produced via the strong interaction or a single leptoquark can be produced in association with a lepton via the hypothesized leptoquark-lepton-quark coupling. Searches for the pair-production of leptoquarks of all three generations have been performed using the $LQ\overline{LQ}\rightarrow l^+l^-q\bar{q}$, $\rightarrow l^\pm \nu q\bar{q}$, and $\rightarrow \nu\bar{\nu}q\bar{q}$, $\rightarrow \tau\bar{b}\tau\bar{b}$ final states. A search for the single production of leptoquarks coupling to muons is based on the decay channel $LQ\mu\rightarrow\mu q \mu$. Upper limits on the production cross sections are given and are used to derive lower limits on the leptoquark masses as a function of the branching fraction $\beta$ of the Leptoquark in a charged lepton and a quark and for different couplings