Top Quark Spin Polarization in e \gamma Collision

TL;DR

This paper studies the spin polarization of single top quarks produced in electron-photon collisions at high energies, identifying the beam direction as the optimal axis for spin analysis, with results comparable to other collider types.

Contribution

It provides the first detailed analysis of top quark spin polarization in eγ collisions across multiple energies, highlighting the beam direction as the preferred spin basis.

Findings

The e+ beam direction is the optimal spin axis for top quark polarization.

Spin asymmetries are significant and comparable to those in pp and ep collisions.

The polarization degree varies with collision energy and spin basis.

Abstract

We investigate the degree of spin polarization of single top quarks in the $e\gamma$ collision via the process $e^{+} \gamma \to t \bar{b} \bar{\nu_{e}}$ with center of mass energies $\sqrt{s}$=0.5, 1 and 1.5 TeV of the parental linear $e^{+}e^{-}$ collider. Dominant spin fractions and spin asymmetries for the various top quark spin bases are investigated. We show that $e^{+}$-beam direction is the favorite top quark spin decomposition axis. It is found to be comparable with the ones in $pp$ and $ep$ collisions.