Search for First and Second Generation Leptoquarks at D\O

TL;DR

This paper reports on a search for first and second generation scalar leptoquarks at Fermilab's p-p collider, setting new mass limits based on the observed data and decay branching ratios, independent of leptoquark coupling assumptions.

Contribution

It provides updated mass limits for first and second generation scalar leptoquarks using DØ data, with improved bounds and a novel approach independent of leptoquark-lepton-quark coupling.

Findings

Mass limits for first generation leptoquarks: 130 GeV/c² (100% decay) and 116 GeV/c² (50% decay).

Mass limits for second generation leptoquarks: 97 GeV/c² (100% decay) and 80 GeV/c² (50% decay).

Limits are independent of leptoquark coupling to leptons and quarks.

Abstract

A search for first and second generation leptoquarks has been done with the D\O \ detector at Fermilab's p\={p} collider with $\sqrt{s}=1.8$ TeV. 95\% C.L. mass limits for first generation scalar leptoquarks have been recently published. The number for the total integrated luminosity used in the first generation leptoquark analysis has changed (via a change in the total inelastic cross section) since the publication. The new limits are 130 GeV/c$^{2}$ and 116 GeV/c$^{2}$ for a respective 100\% and 50\% decay branching ratio of the leptoquark to electron. The preliminary upper limit on the cross section from the search for second generation scalar leptoquarks has set limits on the mass of the second generation leptoquark of 97 GeV/c$^{2}$ for 100\% branching to muons and 80 GeV/c$^{2}$ for 50\% branching. In contrast with leptoquark detection thresholds at e$^{+}$e$^{-}$ and e-p machines, these limits are independent of the unknown coupling of the leptoquark to leptons and quarks.