Collider Signatures of Minimal Flavor Mixing from Stop Decay Length Measurements

TL;DR

This paper explores how measuring the decay length of a long-lived stop at the LHC can reveal minimal flavor violation in supersymmetry, with potential to observe decay signatures and flavor mixing effects.

Contribution

It proposes a method to extract supersymmetric flavor couplings from stop decay length measurements, highlighting the potential to observe flavor violation and decay signatures at the LHC.

Findings

A 1 ps stop lifetime corresponds to a 180 micron impact parameter.

Long-lived stops can produce observable tracks and secondary vertices.

Decay length measurements can distinguish flavor violation scenarios in supersymmetry.

Abstract

We investigate the prospects to extract supersymmetric couplings from a decay length measurement at the LHC. Specifically, we exploit the opportunity of a light and long-lived stop which is pair-produced through gluinos in association with like-sign top quarks. Any observed finite value of the stop decay length strongly supports models in which flavor is broken in a minimal way solely by the Standard Model Yukawa couplings. We find that a 1 picosecond stop lifetime, dominated by t~ -> c chi^0 decays, yields macroscopic transverse impact parameters of about 180 microns. If the lightest neutralino is predominantly higgsino or very close in mass to the light stop, the stop lifetime even increases and allows to observe stop tracks and possibly secondary vertices directly. Measuring squark flavor violation with the stop decay length works also with a gravitino LSP if the neutralino is the NLSP. For this case, opportunities from t~ -> c chi^0 -> c gamma G~ decays for very light gravitinos with mass <= keV are pointed out.