SUSY, the Third Generation and the LHC
Christopher Brust, Andrey Katz, Scott Lawrence, Raman Sundrum
TL;DR
The paper develops a bottom-up Effective SUSY framework with light stops and sbottoms while keeping other superpartners heavy, aiming to preserve electroweak naturalness up to a ~10 TeV scale. It systematically builds minimal LHC-friendly Lagrangians for both 10 TeV and 1 TeV cutoffs, analyzes naturalness constraints, and explores Higgs mass implications, flavor/CP constraints, and the role of R-parity versus RPV, including Dirac gauginos. A major focus is the collider phenomenology of the light subsystem (stops, sbottom, neutralino) under various LSP and RPV/RPC scenarios, showing that early LHC data already constrain part of the parameter space but leave large natural regions open, with 10 fb^-1 data expected to be decisively informative. The work highlights that current searches may be ill-suited for Effective SUSY and argues for optimized strategies, including RPV channels and signatures from Dirac gauginos, to fully probe this economical yet viable realization of natural SUSY.
Abstract
We develop a bottom-up approach to studying SUSY with light stops and sbottoms, but with other squarks and sleptons heavy and beyond reach of the LHC. We discuss the range of squark, gaugino and Higgsino masses for which the electroweak scale is radiatively stable over the "little hierarchy" below ~ 10 TeV. We review and expand on indirect constraints on this scenario, in particular from flavor and CP tests. We emphasize that in this context, R-parity violation is very well motivated. The phenomenological differences between Majorana and Dirac gauginos are also discussed. Finally, we focus on the light subsystem of stops, sbottom and neutralino with R-parity, in order to probe the current collider bounds. We find that 1/fb LHC bounds are mild and large parts of the motivated parameter space remain open, while the 10/fb data can be much more decisive.