Search for $e\to\tau$ Charged Lepton Flavor Violation at the EIC with the ECCE Detector

TL;DR

The paper explores the potential of the Electron-Ion Collider with the ECCE detector to significantly improve the search for charged lepton flavor violation involving electrons and tau leptons, which remains less constrained than muon-related transitions.

Contribution

It presents a simulation study showing that the EIC with ECCE can enhance the sensitivity to $e o au$ CLFV by an order of magnitude, opening new discovery possibilities.

Findings

EIC can identify tau leptons with high efficiency in DIS processes.

Simulation suggests an order of magnitude improvement over current limits.

Focus on the 3-prong tau decay mode with limited background data.

Abstract

The recently approved Electron-Ion Collider (EIC) will provide a unique new opportunity for searches of charged lepton flavor violation (CLFV) and other new physics scenarios. In contrast to the $e \leftrightarrow \mu$ CLFV transition for which very stringent limits exist, there is still a relatively large discovery space for the $e \to \tau$ CLFV transition, potentially to be explored by the EIC. With the latest detector design of ECCE (EIC Comprehensive Chromodynamics Experiment) and projected integral luminosity of the EIC, we find the $\tau$-leptons created in the DIS process $ep\to \tau X$ are expected to be identified with high efficiency. A first ECCE simulation study, restricted to the 3-prong $\tau$-decay mode and with limited statistics for the Standard Model backgrounds, estimates that the EIC will be able to improve the current exclusion limit on $e\to \tau$ CLFV by an order of magnitude.