Prospects on Compositeness and New Vector Bosons at LC with Polarization

TL;DR

This paper explores how polarized electron-positron collider experiments can detect signs of fermion compositeness and new vector bosons by analyzing helicity cross sections, enhancing sensitivity to new physics beyond the Standard Model.

Contribution

It proposes a method using polarized cross sections at a future linear collider to improve bounds on contact interactions and identify new vector bosons like Z' with model-independent analysis.

Findings

Polarized cross sections increase sensitivity to contact interactions.

Helicity separation helps determine chiral structure of new interactions.

Method applicable to Z' searches in extended models.

Abstract

Fermion compositness, and other new physics which can be described by an exchange of very massive particles ($Z^\prime$ boson, leptoquarks, sparticles with R-parity violating couplings), can be manifest itself as the presence of a strong four-fermion contact interaction. For the processes $e^+e^-\to \mu^+\mu^-$, $\tau^+\tau^-$, $\bar{b}b$ and $\bar{c}c$ at a future $e^+e^-$ linear collider (LC) with $\sqrt{s}=0.5$ TeV, we examine the sensitivity of the helicity cross sections to four-fermion contact interactions. If longitudinal polarization of the electron beam were available, two polarized integrated cross sections would offer the opportunity to separate the helicity cross sections and, in this way, to derive model-independent bounds on the relevant parameters. The measurement of these polarized cross sections with optimal kinematical cuts could significantly increase the sensitivity of helicity cross sections to contact interaction parameters and could give crucial information on the chiral structure of such new interactions. In addition, we consider the application of the proposed approach to the search for manifestations of a $Z^\prime$ for typical extended model examples.