Transverse Beam Polarization as an Alternate View into New Physics at CLIC

TL;DR

This paper explores how transverse beam polarization at a 3 TeV CLIC collider can distinguish new physics signals, such as supersymmetry and extra dimensions, from Standard Model backgrounds through azimuthal asymmetries.

Contribution

It demonstrates the use of transverse polarization asymmetries to differentiate between supersymmetric states and Kaluza-Klein excitations, and to analyze Z' couplings with high precision.

Findings

Sign of asymmetries discriminates between spin-0 and spin-1/2 new particles.

SM background from W+W- can be minimized in asymmetry measurements.

Angular distributions at Z'-like resonances provide detailed coupling information.

Abstract

In $e^+e^-$ collisions, transverse beam polarization can be a useful tool in studying the properties of particles associated with new physics beyond the Standard Model(SM). However, unlike in the case of measurements associated with longitudinal polarization, the formation of azimuthal asymmetries used to probe this physics in the case of transverse polarization requires both $e^\pm$ beams to be simultaneously polarized. In this paper we discuss the further use of transverse polarization as a probe of new physics models at a high energy, $\sqrt s=3$ TeV version of CLIC. In particular, we show ($i$) how measurements of the sign of these asymmetries is sufficient to discriminate the production of spin-0 supersymmetric states from the spin-1/2 Kaluza-Klein excitations of Universal Extra Dimensions. Simultaneously, the contribution to this asymmetry arising from the potentially large SM $W^+W^-$ background can be made negligibly small. We then show ($ii$) how measurements of such asymmetries and their associated angular distributions on the peak of a new resonant $Z'$-like state can be used to extract precision information on the $Z'$ couplings to the SM fermions.