Radiatively-driven natural supersymmetry (RNS) potentially reconciles the Z and Higgs boson masses close to 100 GeV with gluinos and squarks lying beyond the TeV scale. Requiring no large cancellations at the electroweak scale in constructing M_Z=91.
2 GeV while maintaining a light Higgs scalar with m_h 125 GeV implies a sparticle mass spectrum including light higgsinos with mass 100-300 GeV, electroweak gauginos in the 300-1200 GeV range, gluinos at 1-4 TeV and top/bottom squarks in the 1-4 TeV range (probably beyond LHC reach), while first/second generation matter scalars can exist in the 5-30 TeV range (far beyond LHC reach). We investigate several characteristic signals for RNS at LHC14. Gluino pair production yields a reach up to m_{tg} 1.7 TeV for 300 fb^{-1}. Wino pair production -- pptotw_2tz_4 and tw_2tw_2 -- leads to a unique same-sign diboson (SSdB) signature accompanied by modest jet activity from daughter higgsino decays; this signature provides the best reach up to m_{tg} 2.1 TeV within this framework. Wino pair production also leads to final states with (WZto 3ell)+eslt as well as 4ell+eslt which give confirmatory signals up to m_{tg} 1.4 TeV. Directly produced light higgsinos yield a clean, soft trilepton signature (due to very low visible energy release) which can be visible, but only for a not-too-small a tz_2-tz_1 mass gap. The clean SSdB signal -- as well as the distinctive mass shape of the dilepton mass distribution from tz_{2,3}totz_1ellell decays if this is accessible -- will mark the presence of light higgsinos which are necessary for natural SUSY. While an e^+e^- collider operating with sqrt{s} 600 GeV should unequivocally reveal the predicted light higgsinos, the RNS model with m_{1/2}> 1 TeV may elude all LHC14 search strategies even while maintaining a high degree of electroweak naturalness.
Imposing electroweak scale naturalness constraints (low Delta_{EW}) on SUSY models leads to mass spectra characterized by light higgsinos ~100-300 GeV, highly mixed top-squarks and gluinos at the 1-5 TeV scale and allows for m_h ~125 GeV. First and s
econd generation squarks can easily live at the 5-20 TeV scale, thus providing at least a partial solution to the SUSY flavor/CP problems. For such models at the LHC, gluino pair production is followed by cascade decays to t- and b-quark rich final states along with multileptons. The reach of LHC14 with 300 fb^{-1} is computed to be around m_{tg} 1.8 TeV. However, the small magnitude of the mu-parameter-- a necessary condition for naturalness-- leads to a unique hadronically quite same-sign diboson (W^pm W^pm) signature from wino pair production. In low Delta_{EW} models with unified gaugino masses, this signature yields a somewhat higher reach up to m_{tg} 2.1 TeV. The smallness of |mu| implies that the ILC should be a higgsino factory in addition to a Higgs factory, and a complete search for SUSY naturalness seems possible for sqrt{s} 600 GeV. Since a thermal under-abundance of higgsino-like WIMP dark matter (DM) is expected, there is ample room for an axion DM contribution. A thorough search for higgsino-like WIMPs can be made by next generation WIMP detectors, such as those with ton-scale noble liquid targets.
In supersymmetric models with light higgsinos (which are motivated by electroweak naturalness arguments), the direct production of higgsino pairs may be difficult to search for at LHC due to the low visible energy release from their decays. However,
the wino pair production reaction tw_2^pmtz_4to (W^pmtz_{1,2})+(W^pmtw_1^mp) also occurs at substantial rates and leads to final states including equally opposite-sign (OS) and same-sign (SS) diboson production. We propose a novel search channel for LHC14 based on the SS diboson plus missing E_T final state which contains only modest jet activity. Assuming gaugino mass unification, and an integrated luminosity > 100 fb^{-1}, this search channel provides a reach for SUSY well beyond that from usual gluino pair production.
