Search for Lepton Flavour Violation at HERA

TL;DR

This study searches for lepton flavor violating leptoquarks in ep collisions at HERA, setting mass exclusion limits up to 712 GeV for muon-quark and 479 GeV for tau-quark couplings, with no evidence found.

Contribution

First comprehensive search for second and third generation leptoquarks via lepton flavor violation at HERA using the full data set.

Findings

No evidence for leptoquark production was observed.

Leptoquarks with coupling 0.3 are excluded up to 712 GeV (muon) and 479 GeV (tau).

Results set new limits on leptoquark masses in ep collisions.

Abstract

A search for second and third generation scalar and vector leptoquarks produced in ep collisions via the lepton flavour violating processes ep to mu-X and ep to tau-X is performed by the H1 Collaboration at HERA. The full H1 ep data sample taken at a centre-of-mass energy of 319 GeV is used for the analysis, corresponding to an integrated luminosity of 411 pb^-1. No evidence for the production of such leptoquarks is observed in the H1 data. Leptoquarks produced in ep collisions with a coupling strength of lambda=0.3 and decaying with the same coupling strength to a muon-quark pair or a tau-quark pair are excluded at 95% confidence level up to leptoquark masses of 712 GeV and 479 GeV, respectively.