Top, GigaZ, MegaW

TL;DR

This paper discusses how precise measurements at the ILC, including top quark and W boson masses, can reveal or constrain new physics, especially supersymmetry, even if particles are too heavy for direct detection.

Contribution

It highlights the potential of ILC precision measurements to probe quantum effects of New Physics and distinguish between the Standard Model and MSSM.

Findings

High sensitivity of ILC measurements to quantum effects of New Physics.

Potential to rule out both Standard Model and MSSM with improved sin^2 theta_eff measurements.

Ability to detect virtual SUSY effects even if SUSY particles are too heavy for LHC detection.

Abstract

We review the physics potential of top mass measurements and the GigaZ/MegaW options of the International Linear Collider (ILC) for probing New Physics models and especially the Minimal Supersymmetric Standard Model (MSSM). We demonstrate that the anticipated experimental accuracies at the ILC for the top-quark mass, m_t, the W boson mass, M_W, and the effective leptonic weak mixing angle, sin^2 theta_eff, will provide a high sensitivity to quantum effects of New Physics. In particular, a new and more precise measurement of sin^2 theta_eff, for which the experimental central value is currently obtained from an average where the most precise single measurements differ by more than three standard deviations, could lead to a situation where both the Standard Model and the MSSM in its most general form are ruled out. Alternatively, the precision measurements may resolve virtual effects of SUSY particles even in scenarios where the SUSY particles are so heavy that they escape direct detection at the LHC and the first phase of the ILC.