Search for First Generation Leptoquarks in ep Collisions at HERA

TL;DR

This paper reports a comprehensive search for first generation scalar and vector leptoquarks in ep collisions at HERA, using the full dataset, finding no evidence but setting new mass exclusion limits up to 800 GeV.

Contribution

The study provides the most stringent constraints to date on first generation leptoquark masses using HERA data, extending previous limits significantly.

Findings

No evidence for leptoquark production was observed.

Leptoquarks with masses up to 800 GeV are excluded at 95% confidence level.

Constraints are set for leptoquark couplings of electromagnetic strength.

Abstract

A search for first generation scalar and vector leptoquarks produced in ep collisions is performed by the H1 Collaboration at HERA. The full H1 data sample is used in the analysis, corresponding to an integrated luminosity 446 pb^-1. No evidence for the production of leptoquarks is observed in final states with a large transverse momentum electron or with large missing transverse momentum, and constraints on leptoquark models are derived. For leptoquark couplings of electromagnetic strength lambda=0.3, first generation leptoquarks with masses up to 800 GeV are excluded at 95% confidence level.