Natural SUSY On Trial: Status of Higgsino Searches at ATLAS Julia - PowerPoint PPT Presentation

Natural SUSY On Trial: Status of Higgsino Searches at ATLAS Julia Gonski Harvard University 25 October 2018 US LHC User’s Association Annual Meeting

SUSY (The Defendant) • Provides unification of forces, dark matter candidate, and solution to hierarchy problem • Higgs mass quadratic corrections cancelled by new supersymmetric partners; higgsinos, stops and gluinos especially influential ➡ What do we search for first? � 2 25 October 2018 J. Gonski

SUSY Mass Spectrum (if we got to pick) • Naturalness = reduce fine ˜ L i , ˜ e i tuning ⟹ 10% ˜ B u 1 , 2 , ˜ ˜ Q 1 , 2 , ˜ d 1 , 2 ˜ W mass ˜ b R ˜ g • Dark matter candidate! ˜ Dominantly (but not purely ) ˜ t L t R ˜ higgsino b L ˜ H • Lightest three higgsinos are compressed ( Δ m ~ few GeV) � 3 25 October 2018 J. Gonski

SUSY Mass Spectrum (if we got to pick) • Naturalness = reduce fine ˜ L i , ˜ e i tuning ⟹ 10% ˜ B Gauginos ~ ~ u 1 , 2 , ˜ ˜ ~ Q 1 , 2 , ˜ d 1 , 2 ˜ B) ( W) ( H) ( W mass Mass Eigenstates ˜ 흌 20 ~ ~ 흌 1± ~ b R 흌 30 ~ ~ 흌 40 ~ 흌 2± 흌 10 ˜ g • Dark matter candidate! ˜ Dominantly (but not purely ) ˜ t L t R ˜ higgsino b L ˜ H weak scale • Lightest three higgsinos are ( < 400 GeV) compressed ( Δ m ~ few GeV) � 4 25 October 2018 J. Gonski

SUSY Mass Spectrum (if we got to pick) • Naturalness = reduce fine ˜ L i , ˜ e i tuning ⟹ 10% ˜ B u 1 , 2 , ˜ ˜ Q 1 , 2 , ˜ d 1 , 2 ˜ B ˜ ˜ W ˜ W H mass ˜ b R χ ± χ ± χ 0 χ 0 χ 0 χ 0 ˜ 2 ˜ ˜ 4 ˜ 3 ˜ 2 ˜ 1 1 ˜ g • Dark matter candidate! ˜ Dominantly (but not purely ) ˜ t L t R ˜ higgsino b L ˜ H weak scale • Lightest three higgsinos are ( < 400 GeV) compressed ( Δ m ~ few GeV) � 5 25 October 2018 J. Gonski

SUSY Mass Spectrum (if we got to pick) • Naturalness = reduce fine ˜ L i , ˜ e i tuning ⟹ 10% ˜ B u 1 , 2 , ˜ ˜ Q 1 , 2 , ˜ d 1 , 2 ˜ B ˜ ˜ W ˜ W H mass ˜ b R χ ± χ ± χ 0 χ 0 χ 0 χ 0 ˜ 2 ˜ ˜ 4 ˜ 3 ˜ 2 ˜ 1 1 ˜ g • Dark matter candidate! ˜ Dominantly (but not purely ) ˜ t L t R ˜ higgsino b L ˜ H weak scale • Lightest three higgsinos are ( < 400 GeV) compressed ( Δ m ~ few GeV) � 6 25 October 2018 J. Gonski

SUSY Mass Spectrum (if we got to pick) • Naturalness = reduce fine ˜ L i , ˜ e i tuning ⟹ 10% ˜ B u 1 , 2 , ˜ ˜ Q 1 , 2 , ˜ d 1 , 2 ˜ B ˜ ˜ W ˜ W H mass ˜ b R χ ± χ ± χ 0 χ 0 χ 0 χ 0 ˜ 2 ˜ ˜ 4 ˜ 3 ˜ 2 ˜ 1 1 ˜ g • Dark matter candidate! ˜ Dominantly (but not purely ) ˜ t L t R ˜ higgsino b L ˜ H weak scale • Lightest three ewkinos are ( < 400 GeV) compressed ( Δ m ~ few GeV) � 7 25 October 2018 J. Gonski

Higgsino Searches at ATLAS • Final state: 2 opposite sign same j q flavor soft leptons q p * W • Challenging! � ± ˜ 1 � 0 ˜ 1 • Low production � 0 ˜ cross section 1 � 0 ˜ 2 * Z p • Small Δ m → low ` ME T , very soft ` leptons � 8 25 October 2018 J. Gonski

Higgsino Searches at ATLAS • Final state: 2 opposite sign same j q flavor soft leptons q p * W • Challenging! � ± ˜ 1 � 0 ˜ 1 - Low production � 0 ˜ cross section 1 � 0 ˜ 2 * Z p - Small Δ m → low ` E Tmiss , very soft ` leptons � 9 25 October 2018 J. Gonski

Higgsino Searches at ATLAS ISR kick = • Final state: 2 E Tmiss trigger opposite sign same j q flavor soft leptons q p * W • Challenging! � ± ˜ 1 � 0 ˜ 1 - Low production � 0 ˜ cross section 1 � 0 ˜ 2 * Z p - Small Δ m → low ` E Tmiss , very soft ` leptons Low m ll ~ Δ m � 10 25 October 2018 J. Gonski

Current Exclusion [1] [1] ATLASSummaryPlots � 11 25 October 2018 J. Gonski

Current Exclusion LEP2 [1] [1] ATLASSummaryPlots � 12 25 October 2018 J. Gonski

Current Exclusion [1] 2L compressed [1] ATLASSummaryPlots � 13 25 October 2018 J. Gonski

⇒ Current Exclusion [1] m~100 MeV Disappearing track Pure higgsino/wino state: Δ m~100 MeV ⇒ long lifetime ~10 -11 s [2] [2] ATL-PHYS-PUB-2017-19 [1] ATLASSummaryPlots � 14 25 October 2018 J. Gonski

Current Exclusion [1] Relic density disfavors pure higgsino LSP! (Well-Tempered Neutralino) [3] [3] arXiv:0601041 [1] ATLASSummaryPlots � 15 25 October 2018 J. Gonski

Areas of Improvement [1] New working point gives us muons down to 3 GeV (2019) [1] ATLASSummaryPlots � 16 25 October 2018 J. Gonski

Areas of Improvement [1] More luminosity New working point gives us muons down to 3 GeV (2019) [1] ATLASSummaryPlots � 17 25 October 2018 J. Gonski

What’s Next? • Natural SUSY is still well-motivated! (& experimental constraints are weakest in the electroweak sector) ˜ g ˜ t - Fine tuning < 10% possible for m( ) < 2.5 TeV and m( ) < 1.5 TeV • Next analysis: 1L + track, softer leptons, HL-LHC! (2026+) 200 400 � 18 25 October 2018 J. Gonski

What’s Next? • Natural SUSY is still well-motivated! (& experimental constraints are weakest in the electroweak sector) ˜ g ˜ t - Fine tuning < 10% possible for m( ) < 2.5 TeV and m( ) < 1.5 TeV [4] • Next analysis: 1L + track, softer leptons, HL-LHC! (2026+) 200 400 [4] arXiv:1611.05873 � 19 25 October 2018 J. Gonski

What’s Next? • Natural SUSY is still well-motivated! (& experimental constraints are weakest in the electroweak sector) ˜ g ˜ t - Fine tuning < 10% possible for m( ) < 2.5 TeV and m( ) < 1.5 TeV [4] • Up next: softer leptons, 1L + track, HL-LHC! (2026+) ? 200 400 [4] arXiv:1611.05873 � 20 25 October 2018 J. Gonski

Backup � 21 25 October 2018 J. Gonski

Precision Corrections to Fine Tuning Buckley, Monteux, Shih arXiv:1611.05873 Λ = �� ��� m 2 H = m 2 H,bare + ∆ m 2 − ∆ m 2 Δ m 2 = | μ | 2 (at tree level) ∆ ≡ 2 δ m 2 H ≤ 10 m 2 h μ ≤ 400 GeV Λ = �� � ��� � 22 25 October 2018 J. Gonski

Why Quasi-Degenerate? study we will take M 1 Depends on neutrino mass matrix in MSSM! Using ( e B 0 , f W 0 , ψ 0 d , ψ 0 u ) basis is is 0 1 0 M 1 � m W t θ W c β m W t θ W s β ✓ ◆ p B C 2 s β m W M 2 0 M 2 m W c β � m W s β B C N 0 = C = M ˜ p M ˜ @ A 0 � m W t θ W c β m W c β � µ 2 c β m W µ 0 m W t θ W s β � m W s β � µ ⇥ ⇤ ⇥ ⇤ f µ , the splittings between the mostly Higgsino states are � � � � � ⇡ m 2 W (1 ⌥ s 2 β ) � � � � � m χ ± � � � m χ 0 2( M 2 + | µ | ) 1 1 � � � � � � � � � ⇡ m 2 � ⇡ m 2 W (1 ± s 2 β ) W ( ±| µ | s 2 β + M 2 ) � � � � � � � � � m χ 0 � � � m χ ± 2( M 2 � | µ | ) , � m χ 0 � � � m χ 0 ( M 2 2 � | µ | 2 ) 2 2 1 1 Wino/bino as lightest electroweakino, # light states is different! • one neutral state for a light bino; • one neutral and one charged state for a light wino. arXiv:1401.1235 � 23 25 October 2018 J. Gonski

But we haven’t found anything yet! The Stop 1500 Limits up-to ~1 TeV in stop mass … but no limits if m(LSP) ≳ 400 GeV � 24 25 October 2018 J. Gonski

But we haven’t found anything yet! The Gluino 2500 � 25 25 October 2018 J. Gonski

ATLAS SUSY Summary � 26 25 October 2018 J. Gonski

2L Higgsino Search • Met > 200 GeV → trigger • p T (jet1) >200 GeV → ISR • | 힓흓 (jet,Met)| > 1.0 → mis-measured Met • nJet(50 GeV) =1,2 → no jets expected from the signal • bJet veto → ttbar background • upper cut on lepton p T → soft leptons in the final state; • upper cut on m ll → small invariant masses expected; • Met/Ht → good discrimination as seen in the Run-2 analysis; • m 휏휏 → Z 휏휏 background; � 27 25 October 2018 J. Gonski

Making E Tmiss with ISR • With no other final state objects, LSPs are back to back, no E Tmiss in event • Require ISR jet: collimate LSPs, generate measurable E Tmiss for trigger p TLSP1 = 100 GeV p TLSP1 = 100 GeV p TLSP2 = 100 GeV p TLSP2 = 100 GeV Total E Tmiss = 0 GeV Total E Tmiss = 200 GeV � 28 25 October 2018 J. Gonski