New Physics Effects from $e^+e^-\to f\bar f$ at a Linear Collider: the Role of $A_{LR, \mu}$

TL;DR

This paper investigates how the longitudinal polarization asymmetry $A_{LR,}$ at a future linear collider can serve as a sensitive indicator of new physics effects, using a framework that incorporates existing LEP1 and SLC data.

Contribution

It introduces a novel application of the Z-peak subtracted approach to analyze the sensitivity of $A_{LR,}$ to universal and non-universal new physics effects at linear colliders.

Findings

$A_{LR,}$ is highly sensitive to universal new physics effects.

The method effectively extends to non-universal effects like contact interactions and graviton exchange.

The approach leverages existing experimental data for improved new physics detection.

Abstract

We discuss New Physics effects in fermion pair production at LC in the framework of the ``Z-peak subtracted approach'', a theoretical scheme that exploits the experimental measurements at LEP1 and SLC as input parameters. In particular, we discuss the role of the longitudinal polarization asymmetry $A_{LR,\mu}$ which turns out to be a very sensitive probe to New Physics of universal type. The extension of the method to non universal effects is discussed and an application is given in two examples: general contact interactions and low energy gravity models with graviton exchange.