The status of GMSB after 1/fb at the LHC

Abstract

We thoroughly investigate the current status of supersymmetry in light of the latest searches at the LHC, using General Gauge Mediation (GGM) as a well-motivated signature generator that leads to many different simplified models. We consider all possible promptly-decaying NLSPs in GGM, and by carefully reinterpreting the existing LHC searches, we derive limits on both colored and electroweak SUSY production. Overall, the coverage of GGM parameter space is quite good, but much discovery potential still remains even at 7 TeV. We identify several regions of parameter space where the current searches are the weakest, typically in models with electroweak production, third generation sfermions or squeezed spectra, and we suggest how ATLAS and CMS might modify their search strategies given the understanding of GMSB at 1/fb. In particular, we propose the use of leptonic M T 2 to suppress tt backgrounds. Because we express our results in terms of simplified models, they have broader applicability beyond the GGM framework, and give a global view of the current LHC reach. Our results on 3rd generation squark NLSPs in particular can be viewed as setting direct limits on naturalness.

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.…”

Stop searches in 2012

“…To enhance the di-lepton mode we need to identify additional sources of missing energy, as compared to tt or W + W − events with their W decay neutrinos. The particles contributing to m T 2 from tt events come from the W + W − subsystem, so for top quarks close to threshold the upper endpoint is m T 2 < m W [33,34]. In contrast, for the stop signal such an endpoint does not exist.…”

Stop the top background of the stop search

“…Because there are missing energies on both decay chains, the stransverse mass M T 2 [45,46] can be a natural variable to identify this type of background event. (M T 2 has been proposed to reduce tt and W + W − backgrounds in the di-lepton search channel [47,48].) The M T 2 for a given event can be interpreted as the minimal mother particle mass compatible with the postulated event topology and an assumed daughter particle mass [49].…”