Experimental status of supersymmetry after the LHC Run-I

Abstract

The ATLAS and CMS experiments at the Large Hadron Collider (LHC) at CERN have searched for signals of new physics, in particular for supersymmetry. The data collected until 2012 at center-of-mass energies of 7 and 8 TeV and integrated luminosities of 5 fb −1 and 20 fb −1 , respectively, agree with the expectation from standard model processes. Constraints on supersymmetry have been calculated and interpreted in different models. Limits on supersymmetry particle masses at the TeV scale have been derived and interpreted generally in the context of simplified model spectra. The constrained minimal supersymmetric standard model is disfavored by the experimental results. Natural supersymmetry scenarios with low supersymmetry particle masses remain possible in multiple regions, for example in those with compressed spectra, that are difficult to access experimentally. The upgraded LHC operating at √ s = 13 TeV is gaining sensitivity to the remaining unexplored SUSY parameter space.

Search for Supersymmetry at the LHC

“…The experimental signature of these models is determined by the nature of the next-to-lightest SUSY particle (NLSP). The results discussed in the following assume that the NLSP is the lightest neutralinoχ [29,30] carried out on the first 3 fb −1 of 13 TeV data already exceed the sensitivity of previous analyses [20] as shown in Fig. 7.…”

“…In the case of the fully hadronic final states this SM background is due to QCD multijet production, where the artificial E miss [14,16,17], CMS from taken from [10][11][12]15], the gray shaded areas correspond to the envelope of all 8 TeV contours, taken from [18][19][20].…”

“…2 the exclusion contours with respect to the gluino and the lightest neutralino masses for gluino-pair production scenarios are shown for the different inclusive supersymmetry search analyses performed at ATLAS with data corresponding to an integrated luminosity of 3.2 fb −1 and at CMS with 2.2 fb −1 of data. The best sensitivity of the analyses performed on data collected at a center-ofmass energy of 8 TeV and about 20 fb −1 of data are shown as a gray area [20]. Twogg SMS with different gluino decays leading to different final state particle topologies are shown.…”

“…High jet multiplicities are targeted by [16], while the W/Z may lead to leptons which are analyzed by [17,21]. Direct gluino decaysg → qqχ 0 1 through squarks assumed to be off-shell lead to rather low multiplicities of energetic jets, significant E miss [20]. The decay topology and the kinematics of the decay products differ significantly, requiring a rich set of experimental analyses.…”

“…Here, the most energetic jet is most likely due to initial-state radiation, while the visible standard model particles of the stop quark decay do not pass the reconstruction thresholds. Previous analyses carried out on the 8 TeV data [20] shown as gray area in Fig. 5 made also use of c-tagging algorithms, that attempt to identify the low energetic c-jet of the flavor changing stop decay possible at low ∆m.…”