Top squarks from the landscape at high luminosity LHC

TL;DR

This paper explores the likelihood of light top squarks in supersymmetric models derived from the string landscape, analyzing their discovery prospects at the high-luminosity LHC within a natural SUSY framework.

Contribution

It provides a landscape-based motivation for natural SUSY with specific top squark mass ranges and evaluates the LHC's potential to discover or exclude these particles.

Findings

HL-LHC can discover top squarks up to 1.7 TeV

Exclusion limits reach up to 2 TeV for top squarks

Most natural SUSY parameter space is accessible at HL-LHC

Abstract

Supersymmetric models with low electroweak finetuning are expected to be more prevalent on the string landscape than finetuned models. We assume a fertile patch of landscape vacua containing the minimal supersymmetric standard model (MSSM) as low energy/weak scale effective field theory (LE-EFT). Then, a statistical pull by the landscape to large soft terms is balanced by the requirement of a derived value of the weak scale which is not too far from its measured value in our universe. Such models are characterized by light higgsinos in the few hundred GeV range whilst top squarks are in the 1-2.5 TeV range with large trilinear soft terms which helps to push m_h~ 125 GeV. Other sparticles are generally beyond current LHC reach and the BR(b -> s\gamma ) branching fraction is nearly equal to its SM value. The light top-squarks decay comparably via \tst_1 -> b\tchi_1^+ and \tst_1 -> t\tchi_{1,2}^0 yielding mixed final states of b\bar{b}+MET, t\bar{b}/\ \bar{t}b + MET and t\bar{t}+ MET. We evaluate prospects for top squark discovery at high-luminosity (HL) LHC for the well-motivated case of natural SUSY from the landscape. We find for HL-LHC a 5\sigma reach out to m_{\tst_1}~ 1.7 TeV and a 95\% CL exclusion reach to m_{\tst_1} ~ 2 TeV. These reaches cover {\it most} (but not all) of the allowed stringy natural parameter space!