Searches for SUSY & Exotics with ATLAS Evelyn Thomson University of Pennsylvania

May 17 2017 BLV 2017 Cleveland, Ohio

1 Outline

Introduction ATLAS speakers in parallel sessions Supersymmetry searches Exotics at the LHC Gluinos Search for New Phenomena in Dijet Events Scalar top Lydia Beresford (May 15 14:20) Electroweakinos Searches for new phenomena in leptonic final states Exotic searches Chikuma Kato (May 15 14:40) Dilepton Search for vector-like quarks Dijet Takuya Tashiro (May 15 15:00) Diboson Lepton number violation searches Vector-like quarks Antonio Salvucci (May 16 14:50) Dark matter Dark Matter Summary Dark Matter searches with the ATLAS Detector Stanislav Suchek (May 15 14:40)

2 The Large Hadron Collider

Run 2 proton collisions at √s=13 TeV Delivered 42 fb-1 in 2015+2016 Goal 90 fb-1 more in 2017+2018 Run 3 2021-2023 Goal 300 fb-1 Phase II upgrades -> High Luminosity 2026-2035 Goal 3000 fb-1

3 Searching for Supersymmetry

SUSY pair production R-Parity R=(-1)3B-3L+2s

1 pb 1 pb

Status and implications of BSM searches 1 fb E. Halkiadakis, G. Redlinger, D. Shih arXiv:1105.1110, arXiv:hep-ph/9611232 Ann.Rev.Nucl.Part.Sci. 64 (2014) 319-342 4 Searching for Supersymmetry

SUSY pair production R-Parity R=(-1)3B-3L+2s LHC signature depends on LSP and R-Parity

1 pb

Figure from S. Spinner

1 fb ATLAS-CONF-2015-018 Run 1 Constraints on promptly decaying SUSY arXiv:1105.1110, arXiv:hep-ph/9611232 particles with lepton-number-violation and RPV 5 Solving rapid proton decay in SUSY

R-Parity Conservation R=(-1)3B-3L+2s R-Parity Violation R=(-1)3B-3L+2s Forbids violation of baryon and lepton number Allows violation of baryon OR lepton number Proton stable Proton stable Lightest Supersymmetric Particle (LSP) stable LSP decays through small RPV couplings Significant consequences for LHC signatures Significant consequences for LHC signatures Pair production of superpartners Pair production of superpartners High MET from stable LSPs No MET since collider LSP decays LSP is a dark matter candidate (must be neutralino) Decaying dark matter ad hoc introduction of new quantum number Add an extra local gauge symmetry to MSSM 6 Gluino pair production

Simplified model with squarks decoupled Direct decay to LSP

Four high pT jets High effective mass (meff) from High MET scalar sum of jet pT and MET Exclude gluino up to 2000 GeV for low LSP mass Similar limits for more complicated decay chains and pMSSM

ATLAS-CONF-2017-022 7 Background estimation

Showing control regions for major backgrounds 푡푡 → 휏휐푞푞 ′푏푏 and hadronic tau decay Z+jets with 푍 → 휐휐 W+jets with 푊 → 휏휐 and hadronic tau decay Normalize backgrounds using control regions Check in validation regions (not shown here)

ATLAS-CONF-2017-022 8 Scalar top search Direct production of stop pairs

4 high pT jets, 1 b-tag MET > 250 GeV

Exclude stop up to 950 GeV for low LSP Improved reach in region where stop mass close to sum of top and LSP New search region with ISR Exclude stop between 235-590 GeV

ATLAS-CONF-2017-020 see also 2017-037 for 1 lepton and 2017-034 for 2 lepton 9 Exploring LSP type

One step decay Two step decay significant and W bosons may be off-shell

For results, please see Keisuke Yoshihara’s talk at LHCP this morning and ATLAS-CONF-2017-037

10 Gluino with RPV

LSP has baryon-number violating decay One lepton 5 to 12 or more jets, b-tags No MET Data-driven backgrounds Exclude gluino up to 2100 GeV for Bino LSP

arXiv:1704.08493 11 Stop with RPV (Bino LSP or Higgsino LSP)

LSP has baryon-number violating decay One lepton 5 to 12 or more jets, b-tags No MET Data-driven backgrounds Interpretation for scalar top production BinoBinoLSPLSP Wino LSP (no leptons) Higgsino LSP

arXiv:1704.08493 12 Stop RPV 2x2

Baryon-number violating decay 2 resonances decay to 2 jets No MET, background from QCD multijets Data-driven estimate

Average mass of di-jet pairs

For each mavg bin Preselection data Preselection data ND=NAxNF/NC

Mass Asymmetry Production angle ATLAS-CONF-2017-025 13 Stop RPV 2x2

Baryon-number violating decay 2 resonances decay to 2 jets Decay to two light quarks Exclude stop from 100 to 410 GeV

ATLAS-CONF-2017-025 14 Stop RPV 2x2

Baryon-number violating decay 2 resonances decay to 2 jets Decay to two light quarks Exclude stop from 100 to 410 GeV Decay to a b quark and light quark Exclude stop from 100 to 470 and 480 to 610 GeV

ATLAS-CONF-2017-025 15 휏푏휏푏 PLB 732 (2014) 325 Stop RPV with U(1)B-L Minimal model with extra U(1) B-L gauge group, spontaneously broken by RH sneutrino Stop LSP with lepton number violating decay 2 resonances decay to lepton and b-quark 2 leptons ee, eμ, μμ, 2 jets, 1 b-tag Backgrounds normalized in control regions 휇푏휇푏 푒푏푒푏 푡푡, Wt, Z/γ*+jets

Mass Asymmetry ATLAS-CONF-2017-036 Highest Mass Lepton b-jet pair 16 Electroweakinos Decay via W, Z, h bosons

Decay via scalar leptons Run 1 results, Run 2 results soon

→ Decreasing ∆M Decreasing

Increasing ∆M → Assumptions: LSP is pure bino; NLSP is pure wino; large ∆M between NLSP and LSP ATLAS SUSY summary plots 17 Electroweakinos 4 lepton (RPV)

LSP has lepton-number violating decay 4 isolated leptons from massive LSP decays Backgrounds ttZ, ZZ with 4 leptons Reducible with 1 or 2 fake leptons

Exclude wino NLSP below 1000 GeV for LSP decays to electrons or muons

ATLAS-CONF-2016-075 18 Disappearing track IBL Run 2 33 mm New pixel layer at 33 mm for Run 2 (IBL) 120 mm Run 1 New tracklet reconstruction (4 hits) 300 mm completely in pixel detector Sensitive to charged particles with shorter lifetimes than Run 1 Long-lived Chargino small ∆M for Wino LSP

ATLAS-CONF-2017-017 19 Long-lived particles summary

Long-lived chargino Long-lived gluino R-hadron Only 2015 data

See new ATLAS-CONF-2017-026 displaced vertices SUSY-Summary-Plots 20 Outline

Introduction Highest dijet invariant mass 8.12 TeV, both jets have pT 3.79 TeV Supersymmetry searches Gluinos Scalar top Electroweakinos Exotic searches Dilepton Dijet Diboson Vector-like quarks Dark matter Summary

21 Dijet resonances

Data-driven background Dijet invariant mass Angular distribution

arXiv:1703.09127 22 Searches with same flavor leptons

20 GeV for ee Experimental mass resolution at 3 TeV 420 GeV for μμ

ATLAS-CONF-2017-027 23 Searches with same flavor leptons Exclude Z’ with mass below 4 TeV at 95% CL Exclude llqq contact interactions with energy scale Λ below 23 to 40 TeV

ATLAS-CONF-2017-027 24 Searches with Lepton Flavor Violation Only 2015 data Updates for summer

Eur. Phys. J. C76 (2016) 541 25 Diboson resonances

Search for 푉퐻 → 푞푞 ′푏푏 with high Lorentz boost

Two high pT large R=1.2 jets (450, 250 GeV) Jet mass > 50 GeV Higher mass jet with 1 or 2 b-tagged track jets Lower mass jet has two-prong substructure Background 90% from QCD multijets Data-driven background from sidebands Above 2.5 TeV, Higgs Lorentz boost high enough for overlap of decay of two b hadrons 1 tag has better sensitivity above 2.5 TeV ATLAS-CONF-2017-018 26 Diboson resonances

Search for 푉퐻 → 푞푞 ′푏푏 with high Lorentz boost

Two high pT large R=1.2 jets (450, 250 GeV) Jet mass > 50 GeV Higher mass jet with 1 or 2 b-tagged track jets Lower mass jet has two-prong substructure Data are in agreement with Standard Model expectations Largest excess observed at 3.0 TeV Local significance of 3.3σ Global significance of this excess is 2.2σ ATLAS-CONF-2017-018 27 Vector-like Quarks: ZtZt final state

Spin-1/2 but not chiral like standard model quarks Vector: same left and right-handed couplings Bare mass terms allowed in Lagrangian Solves hierarchy problem for Higgs boson mass TT pair production One T → Zt decay with 푍 → 휐휐 HtHt Signature One lepton

4 high pT jets MET Exclude T mass below 1.16 TeV with 100% T→ Zt Here T->Zt ATLAS-CONF-2017-015 See also for T->Wb EXOT-2016-14 See also for T->Ht ATLAS-CONF-2016-104 ZtZt WbWb 28 Vector-like Quarks: WbWb final state

Optimized for TT, also sensitive to BB, XX, YY One T → Wb decay with W→ 푙휐 Signature One lepton, MET

3 high pT jets 1 b-tag HtHt Large R jet for boosted W Exclude T mass below 1.35 TeV with 100% T→ Wb Exclude B mass below 1.25 TeV with 100% B→ Wt

EXOT-2016-14 ZtZt WbWb 29 Dark matter search

Mono-photon+MET Backgrounds 푍 → 휐휐 + QED ISR Cleaner background than in mono-jet+MET with QCD ISR

ATLAS-EXOT-2016-32 30 Dark matter search

Mono-photon+MET Set limits in 2D plane (mediator mass, DM mass)

Proton collisions so larger gq gives better limits

ATLAS-EXOT-2016-32 31 Dark matter and dijets

Dark matter mediator produced in proton- proton collisions, so must also decay to dijets

Dijet searches give strong limits for gq=0.25, weaker limits for smaller gq=0.1

Exotics summary plots 32 Summary

Searches for strongly produced SUSY not showing any deviations from SM…yet Searches for rarer electroweak produced SUSY starting to explore new territory in Run 2 Searches for exotics not showing any deviations from SM…yet

New Supersymmetry results New Exotics results 33 Backup

34 rd Gluino pair production: 3 gen ATLAS-CONF-2017-021

All final states have 4 b-jets Require 3 b-tags Combine multiple search regions 4-9 jets Low-Int-High effective mass 0 or 1 lepton Exclude gluino below 1900 GeV for low LSP mass, expected limits slightly higher

0 tops 4 tops

35 Pileup

Reconstruction of charged particle tracks important to remove effects of pileup Select anti-kt jets with tracks from primary vertex (hard scatter) Calculate MET with calibrated objects and other tracks from primary vertex

36 Standard Model

Three Fundamental Forces of Nature precisely described by Quantum Field Theory SU(3) x SU(2)L x U(1) Strong force (QCD) carried by massless gluons Electro-Weak force carried by massless photon (QED) and massive W+, W-, Z0 (Weak) Higgs field provides mass to W and Z, and to elementary particles ? Right-handed neutrinos don’t interact with any of the force-carriers ? Is it valid up to Planck scale (1019 GeV) where gravity becomes important? Hierarchy problem for scalar Higgs boson: fine-tune radiative corrections to 1 part in 1032

100 000 000 000 000 000 000 000 000 000 000 - 99 999 999 999 999 999 999 999 999 999 999 37 Dark Matter

All observed particles are only Solar System 1/5 of mass in the universe What is dark matter? Does it interact with the Higgs? Is it a supersymmetric particle? Is it the QCD axion?

M31 Galaxy

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