Gaugino-Only SUSY Scenarios at Galileo Galilei Institute
Musings on Gaugino-Only SUSY scenarios focusing on gaugino/higgsino states, gaugino production, two-step scenarios, recent reports, and single multiplet scenarios. Discusses different particle accountings, production cross sections, and exploration by experiments like ATLAS and CMS.
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Some Musings About Gaugino-Only SUSY Scenarios Galileo Galilei Institute Week I Collider Physics and the Cosmos August 28-September 1, 2017 Bruce Schumm UC Santa Cruz
Question to consider: In scenarios in which gaunginos/higgsinos are the only accessible states, are our SUSY searches as comprehensive as possible? LSP itself is not unlikely to be heavy Gienvieve Belanger
Priors Assume gauginos/higgsinos are only accessible SUSY states Assume R-Parity conservation throughout Not considering gauge mediation (so assume N1 is LSP) For the most part, assume significantly different scales for gaugino mass parameters (M1, M2, ) I believe this leads to the following particle accounting: One purely Bino-like state (N) Three purely Wino-like (1N,1C ) Four purely Higgsino-like states: (2N,1C )
Gaugino Production Algebra of SU(2)xU(1) forbids leading-order pair production of any admixture of Bino or neutral Wino states. Wino-like cross sections GeV/fb N2-C1 C1-C1 Tot 200 1807 903 2710 400 121 58.6 179.6 600 20.1 9.50 29.6 800 4.76 2.21 6.97 1000 1.34 0.62 1.96 Higgsino-like cross sections (N1-N1 not included since that s just LSP-LSP) GeV/fb N2-C1 C1-C1 N1-N2 Tot 200 424 244 244 912 400 28.4 16.3 15.7 60.4 600 4.74 2.68 2.53 9.95 800 1.12 0.63 0.59 2.34 1000 0.31 0.18 0.16 0.65
Two-step Scenarios Singlet LSP (bino) NLSP is multiplet that is produced; decays promptly to LSP Example: Wino-bino model; explored in depth by ATLAS, CMS
Recent Report on Wino-Bino Scenario: Combination of modes for Wino-Like NLSP; Bino-Like LSP from CMS [what about Higgsino case?] Combined search for electroweak production of charginos and neutralinos in pp collisions at 13 TeV CMS PAS SUS-17-004 July 11 2017 Model: Degenerate wino, N2-C1 production. C1 W N1 (100%) N2 (Z,H) N1 (0,50,100%) N2 H/Z N1 N2 H N1 N2 Z N1
Single (Nearly Degenerate) Multiplet Scenarios One of M1, M2, is accessible; other two decoupled : Higgsino states (N1, N2, C1 ) M2: Wino states (N1, C1 ) M1: Bino (N1 only) Small (constrained?) splitting between states within multiplet
Higgsino LSP Scenario Selections involves leptons, MET recoil against stiff jet Open up small splitting by requiring Boosted scenario Results soon from ATLAS (CMS too?) Should have sensitivity to splittings as low as ~2 GeV for some range of mass scale
Higgsino Spectrum: Expected Splitting Scale [Remaining plots, and many of the notions, from Satoshi s presentation yesterday] M1, M2 Decoupled Which leads to different approaches, related to lifetime:
Nominal SUSY splittings yield path length large enough to measure in tracker Higgsino case Wino case: Smaller splittings, longer c
Disappearing Track Searches Wino case; ATLAS Higgsino projection; Shirai ? Aggressive tracking
Degenerate Multiplet Approach Disappearing tracks are promising approach Soft hadrons, leptons from N2/C1 decays under exploration Periods of running with reduced field warranted? What about dE/dX? Reasonable measurement possible with ~5 Si layers when < 1 Metatsable C1? [Analyses probably available, but doesn t seem to be within the ATLAS SUSY effort. Are there any hidden model dependencies? (e.g. I believe there might be a lepton veto for the ATLAS disappearing track analysis)
Bino LSP Scenario What if DM is pure Bino, and this is only accessible state? Not produced in colliders What are direct detection mechanisms?
Bigger Picture: Dark matter may be SUSY-like; but not SUSY (how seriously do we take mass splittings? Perhaps just guidance?) ATLAS boosted Higgsino and disappearing track searches are maybe just first passes; how to we improve them, make them more comprehensive (lepton requirements/vetos)? Are there any intellectual holes in our understanding/coverage of gaugino/higgsino-only SUSY?
