Boosted tau lepton as a microscope and macroscope

TL;DR

This paper proposes using boosted, long-lived tau leptons as a novel tool to probe new physics beyond the standard model, enabling precise measurements of tau properties and detection of high-energy cosmic neutrinos.

Contribution

It introduces a new approach to utilize long-lived boosted tau leptons as a microscope and macroscope for advanced particle physics and astrophysics investigations.

Findings

Potential to measure tau's anomalous magnetic moment with unprecedented precision.

Ability to detect high-energy cosmic neutrinos at TeV to PeV scales.

Demonstrates the feasibility of using tau leptons as probes for new physics.

Abstract

Anomalies from the LHCb lepton flavour universality and Fermilab muon anomalous magnetic momentum, show tantalizing hints of possible new physics from the lepton sectors. Due to its large mass and shorter lifetime than muon, the tau lepton is believed to couple more to possible new physics beyond the standard model. Traditionally, tau leptons are probed through the decay products due to tau's short life time. On the other hand, at a high energy scale, a large fraction of tau leptons could be boosted to a much longer life time and fly a visible distance from several centimetres up to kilometer length scale, yet very informative to new physics beyond the standard model or high energy cosmic rays. In this article, we show unique yet promising tau physics by exploiting long-lived taus as a microscope or macroscope, to measure tau's anomalous magnetic momentum to an unprecedented level of accuracy and detect high energy cosmic neutrinos at the 1 TeV to 1 PeV scale, respectively.