Toward full LHC coverage of natural supersymmetry

Abstract

We argue that combining just a handful of searches for new physics at Run I of the LHC is sufficient to exclude most supersymmetric extensions of the Standard Model in which the gluino is kinematically accessible and the spectrum is natural. Such models typically give rise to significant E / T , top quarks and/or high object multiplicity, and we show that having even one of these signatures generally results in stringent limits. We also identify, among models that lack these signatures, the few gaps in coverage remaining, and propose search strategies to close these gaps. Our results are general and independent of the details of the spectrum, assumptions about minimality, R-parity, etc. Our analysis strategy should remain applicable when the LHC moves to higher energy. Central to our argument are ATLAS and CMS searches for many jets and low E / T , a proposed lepton + many jets search, an ATLAS search for 6-7 high-p T jets, and a reexamination of the control and signal regions of the CMS black hole search.

Supersymmetric crevices: Missing signatures ofR-parity violation at the LHC

“…This capitalizes on both of the distinctive features of this type of RPV, much as the multijet + MET search is powerful for final states with neutrinos. Searches of this type have been proposed previously in the literature [27,59] in the context of models with high jet multiplicity and leptons from W 's, Z's or tops; our models represent another qualitatively different scenario that could be probed by this type of search. The specific MC studies in these works consider selecting events with many jets, one lepton and either moderate MET or b-jets; to cover the models we discussed one could relax any MET or b-tag cuts but instead look for events with two (possibly same-sign) leptons.…”

“…Our exploration of these types of RPV spectra is in contrast to earlier studies of RPV collider phenomenology assuming specific models for the RPV couplings and/or particular minimal spectra, including "natural" spectra [26][27][28][29][30][31][32][33][34][35][36][37]. By including all of the colored superpartners in our simplified models we aim to identify models in which RPV hides a large total SUSY production cross-section from LHC searches.…”

Search for new phenomena in a lepton plus high jet multiplicity final state with the ATLAS experiment using s = 13 $$ \sqrt{s}=13 $$ TeV proton-proton collision data

“…In this case, the tttt sample is generated with the MG5 aMC@NLO 2.2.2 event generator interfaced to Pythia 8.186 using the NNPDF23LO PDF set and the A14 tune. 2 The same final state can be produced by requiring a non-zero λ 313 RPV coupling, however the minimal flavour violation hypothesis [26] favours a large λ 323 coupling [27].…”

“…In order to account for acceptance effects due to the different kinematics in events with high jet multiplicity, the probability of further b-tagged jets entering the acceptance is also taken into account. The extrapolation to one additional jet can be parameterized as: 2) where N tt+jets j is the number of tt+jets events with j jets and f j,b is the fraction of tt events with j jets of which b are b-tagged. The parameters x i describe the probability of one additional jet to be either not b-tagged (x 0 ), b-tagged (x 1 ), or b-tagged and causing a second b-tagged jet to move into the fiducial acceptance (x 2 ).…”

“…However, one gap in the search coverage, as pointed out in refs. [1,2], is in final states with one or more leptons, many jets and no-or-little missing transverse momentum (the magnitude of which is denoted by -1 - …”