CP violating anomalous tau lepton coupling $\bar{\tau}\tau V$ via a spin-0 unparticle

TL;DR

This paper investigates how a spin-0 unparticle could contribute to CP violation in tau lepton interactions, potentially exceeding standard model effects and comparable to other new physics models, using recent LHC data for parameter constraints.

Contribution

It introduces a novel analysis of spin-0 unparticle effects on tau lepton electromagnetic and weak properties, highlighting their potential significance over standard model predictions.

Findings

Unparticle contributions can surpass SM contributions.

Unparticle effects are comparable to other SM extensions.

Constraints are derived from recent LHC mono-jet data.

Abstract

The tau is the only known lepton that can decay hadronically. From this class of decays, high precision measurements of several quantities can be extracted: the CKM matrix element $V_{us}$, the mass of the strange quark, etc. Also, as a result of its large variety of decay channels, the study of the tau lepton represents an interesting tool to search for CP violation and other new physics effects. In this work, a spin-0 unparticle is considered and its contributions to the electromagnetic and weak properties of the tau lepton are calculated. It is found that such contributions can be greater than the standard model (SM) contributions, though they can be of similar order of magnitude than the contributions from other SM extensions, such as an extension of the minimal supersymmetric standard model with vectorlike multiplets. For the unparticles parameters, the most recent CMS bound from mono-jet production plus missing transverse energy at the LHC are considered.