Light non-degenerate squarks at the LHC

TL;DR

This paper reinterprets LHC squark search results, showing that relaxing the assumption of universal squark masses allows for significantly lighter non-degenerate squarks, especially within models like MFV and alignment scenarios.

Contribution

It demonstrates that current experimental bounds on squark masses can be substantially weakened when considering non-degenerate mass spectra and specific flavor models.

Findings

Second-generation squark singlets as light as 400 GeV are allowed.

Down-type squark singlets can be as light as 600 GeV in MFV scenarios.

Squark mass bounds are less restrictive under non-universality assumptions.

Abstract

Experimental bounds on squarks of the first two generations assume their masses to be eightfold degenerate, and consequently constrain them to be heavier than ~ 1.4 TeV when the gluino is lighter than 2.5 TeV. The assumption of squark-mass universality is neither a direct consequence of Minimal Flavor Violation (MFV), which allows for splittings within squark generations, nor a prediction of supersymmetric alignment models, which allow for splittings between generations. We reinterpret a recent CMS multijet plus missing energy search allowing for deviations from U(2) universality, and show that the squark bounds are significantly weakened: a 400 GeV second-generation squark singlet is allowed, even with exclusive decays to a massless neutralino; and in an MFV scenario, the down-type squark singlets can be as light as 600 GeV provided the up-type singlets are pushed up to 1.8 TeV, for a 1.5 TeV gluino and decoupled doublet squarks.