Events with Isolated Leptons and Missing Transverse Momentum in ep Collisions at HERA

TL;DR

This paper analyzes events with isolated leptons and missing transverse momentum in HERA ep collisions, finding an excess in e+ p data that could indicate new physics beyond the Standard Model.

Contribution

It presents the first detailed analysis of such events in the H1 experiment across multiple lepton channels using data from 1994-2006, highlighting a potential anomaly in e+ p collisions.

Findings

Good agreement with SM in e- p data

An excess with 3.4 sigma significance in e+ p data at high transverse momentum

Potential hint of new physics beyond the Standard Model

Abstract

The analysis of events with isolated leptons and missing transverse momentum in the H1 experiment is discussed for the electron, muon and tau channels. In the Standard Model (SM) framework, production of real W-bosons gives rise to such topologies. Contributions to the background are dominated by QCD processes. An excess of observed signal over background presents a chance of the discovery of new physics. The results using the HERA 1994-2006 data set corresponding to 341 pb^-1 are presented. While the e- p sample shows good agreement between data and SM expectation, in e+ p collisions an excess over the SM expectation with 3.4 sigma significance is observed at high hadronic transverse momentum.