Precision Natural SUSY at CEPC, FCC-ee, and ILC

TL;DR

This paper evaluates the potential of future lepton colliders like CEPC, FCC-ee, and ILC to test natural supersymmetry through precision measurements, addressing blind spots and alternative probes for various SUSY scenarios.

Contribution

It provides projections of the sensitivity of future colliders to natural SUSY, including strategies to overcome blind spots and explore non-colored top partners.

Findings

Future colliders can probe natural SUSY with a few percent fine-tuning.

Electroweak precision observables are crucial, especially for non-colored top partners.

Complementary bounds from Higgs decays and flavor physics enhance sensitivity.

Abstract

Testing the idea of naturalness is and will continue to be one of the most important goals of high energy physics experiments. It will play a central role in the physics program of future colliders. In this paper, we present projections of the reach of natural SUSY at future lepton colliders: CEPC, FCC-ee and ILC. We focus on the observables which give the strongest reach, the electroweak precision observables (for left-handed stops), and Higgs to gluon and photon decay rates (for both left- and right-handed stops). There is a "blind spot" when the stop mixing parameter Xt is approximately equal to the average stop mass. We argue that in natural scenarios, bounds on the heavy Higgs bosons from tree-level mixing effects that modify the bottom Yukawa coupling together with bounds from b to s gamma play a complementary role in probing the blind spot region. For specific natural SUSY scenarios such as folded SUSY in which the top partners do not carry Standard Model color charges, electroweak precision observables could be the most sensitive probe. In all the scenarios discussed in this paper, the combined set of precision measurements will probe down to a few percent in fine-tuning.