SUSY, the Third Generation and the LHC

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, Rparity 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.

Compressed electroweakino spectra at the LHC

“…The spectrum then contains two light neutralinos χ 0 1,2 and one chargino χ ± 1 which are gaugino-like and whose mass splitting is controlled by M 2 − M 1 , and heavier states at the scale µ which are higgsino-like. In the context of Natural SUSY [21][22][23][24][25] the opposite limit is achieved, namely µ ∼ O(100) GeV and M 1 , M 2 1 TeV. Qualitatively the same spectrum is obtained, but with the light (heavy) states being Higgsino (gaugino)-like.…”

NSUSY fits

“…With gaugino masses assumed heavy, of order M SU SY , light charginos and neutralinos are almost pure Higgsinos, with mass given by µ up to corrections that we neglect. To a lesser degree, the gluinosg are also expected to be light due to their contribution to two-loop corrections to the Higgs mass parameter, which leads to the rough estimate mg 2mt (4mt) for a Majorana (Dirac) gluino [6]. In practice, we can also decouple these somewhat heavier gluinos in our analysis.…”

Probing light higgsinos in natural SUSY from monojet signals at the LHC

“…All these significantly jeopardize the naturalness of MSSM with a standard sparticle spectrum. Therefore, it is imperative to consider the possibly hidden parameters space where the theory maintains naturalness, and look for other strategies for verifying such natural SUSY models at the LHC [13][14][15][16][17]. In this work, we investigate the possibility of monojet signals induced by light higgsinos at 14 TeV high-luminosity LHC(HL-LHC) as a probe of natural SUSY.…”