A Search for Leptoquark Bosons in e^-p Collisions at HERA

TL;DR

This paper reports a search for leptoquark bosons in electron-proton collisions at HERA, finding no evidence and setting mass exclusion limits up to 290 GeV for certain couplings.

Contribution

It provides the first constraints on scalar and vector leptoquarks using electron-proton collision data at HERA with electron beams.

Findings

No evidence for leptoquark production was observed.

Leptoquarks with electromagnetic strength coupling are excluded up to 290 GeV.

Results complement previous positron-based searches.

Abstract

A search for scalar and vector leptoquarks coupling to first generation fermions is performed in the H1 experiment at the ep collider HERA. The analysis uses e^- p data collected in 1998 and 1999 at a centre-of-mass energy of 320 GeV, corresponding to an integrated luminosity of 15 pb^-1. No evidence for the direct production of such particles is found in a data sample with a large transverse momentum final state electron or with large missing transverse momentum, and constraints on leptoquark models are established. For a Yukawa coupling of electromagnetic strength leptoquarks are excluded for masses up to 290 GeV. This analysis complements the leptoquark searches performed previously using data collected whilst HERA was operating with positrons instead of electrons.