Search for Leptoquark Bosons in ep Collisions at HERA

TL;DR

This study searches for scalar and vector leptoquarks in electron-proton collisions at HERA, finding no evidence but setting new mass limits up to 325 GeV for certain couplings.

Contribution

First comprehensive search for leptoquarks at HERA with the full 1994-2000 dataset, establishing improved mass constraints.

Findings

No evidence of leptoquark production in the data.

Leptoquarks with masses up to 275-325 GeV are excluded for electromagnetic-strength couplings.

Limits surpass previous H1 constraints.

Abstract

A search for scalar and vector leptoquarks coupling to first generation fermions is performed using the e^+p and e^-p scattering data collected by the H1 experiment between 1994 and 2000. The data correspond to a total integrated luminosity of 117 pb^{-1}. No evidence for the direct or indirect production of such particles is found in data samples with a large transverse momentum final state electron or with large missing transverse momentum. Constraints on leptoquark models are established. For leptoquark couplings of electromagnetic strength, leptoquarks with masses up to 275-325 GeV are ruled out. These limits improve and supercede earlier H1 limits based on subsamples of the data used here.