Natural SUSY endures

Abstract

Abstract:The first 1 fb −1 of LHC searches have set impressive limits on new colored particles decaying to missing energy. We address the implication of these searches for naturalness in supersymmetry (SUSY). General bottom-up considerations of natural electroweak symmetry breaking show that higgsinos, stops, and the gluino should not be too far above the weak scale. The rest of the spectrum, including the squarks of the first two generations, can be heavier and beyond the current LHC reach. We have used collider simulations to determine the limits that all of the 1 fb −1 searches pose on higgsinos, stops, and the gluino. We find that stops and the left-handed sbottom are starting to be constrained and must be heavier than about 200-300 GeV when decaying to higgsinos. The gluino must be heavier than about 600-800 GeV when it decays to stops and sbottoms. While these findings point toward scenarios with a lighter third generation split from the other squarks, we do find that moderately-tuned regions remain, where the gluino is just above 1 TeV and all the squarks are degenerate and light. Among all the searches, jets plus missing energy and same-sign dileptons often provide the most powerful probes of natural SUSY. Overall, our results indicate that natural SUSY has survived the first 1 fb −1 of data. The LHC is now on the brink of exploring the most interesting region of SUSY parameter space.

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.…”

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.…”

Linking natural supersymmetry to flavour physics

“…13 To be precise, the shift of right-handed sbottom and left-handed stau from the light to the heavy set leads also to a very mild change in the coefficients of the terms already present in eq. (6.1).…”

“…The new LHC lower bounds on the superpartner masses [2,3], stronger for the first two generations of squarks than for the third one, revive the interest in such a spectrum. 1 Recently, several new ideas have been proposed to explain such a spectrum [7][8][9][10][11][12] and detailed LHC analysis were performed [13][14][15].…”