SUSY: SOFT PHYSICS & INTERPRETATION CHALLENGES Young Theorists - PowerPoint PPT Presentation

SUSY: SOFT PHYSICS & INTERPRETATION CHALLENGES Young Theorists Forum @ Durham Jesse Liu University of Oxford 12 January 2017 Based on Alan Barr & JL arXiv:1605.09502 | arXiv:1608.05379 SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 1

F O C U S O F T A L K LHC: testing relativity + quantum theory Interpretation: what do the searches mean? Soft physics: experimental challenges SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 2

1950 1960 1970 1980 1990 2000 2010 Particle Zoo era: is there a theory for particles? DATA Predictions Consistency ? ? “ A theory Had I foreseen this, I would for particle have gone into botany physics? - Enrico Fermi or Wolfgang Pauli ? ? Relativity Quantum PRINCIPLES SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 3

1950 1960 1970 1980 1990 2000 2010 Golden age: experiment & theory triumph DATA Predictions Consistency “ CORE The most dramatic lasting impact is realising that this THEORY structure is almost inevitable SM+GR - Natalia Toro Relativity Quantum PRINCIPLES SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 4

1950 1960 1970 1980 1990 2000 2010 In search of the new particle zoo DATA STRIKING OBSERVATIONAL INCONSISTENCIES Predictions Consistency “ Now that the Standard Model CORE is complete, there are no THEORY BEYOND further no-lose theorems… SM+GR We are in a data driven era - Ian Shipsey Naturalness? Relativity Quantum Unification? Minimality? PRINCIPLES SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 5

D A R K N E S S O F U N K N O W N Where do we start searching? SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 6

LAMPPOSTS EXIST: SEARCH THERE FIRST Relativity + quantum underpins supersymmetry L H C Sterile neutrinos ADMX HPS Dark photons D > 4 Minimality AMS SHiP Unification Axions Z’ bosons EHT LISA Naturalness R-parity violation LSST APEX Light gluino, stops Composite Higgs IAXO D U N E WIMP dark matter Beyond the lamppost Beyond the lamppost Jets + MET searches theories? experiments? NEW PHYSICS AT WEAK SCALE IS theoretically motivated + experimentally observable SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 7

Easy: how do we read SUSY limits? Simplified (toy) models m(lightest SUSY daughter) e.g. neutralino Typical limit Kinematically Forbidden s h a p e Excluded 95% confidence m(SUSY mother) e.g. gluino SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 8

Easy: how do we read SUSY limits? Simplified (toy) models m(lightest SUSY daughter) e.g. neutralino Squished* phase space Decreasing acceptance A Typical limit Plentiful Kinematically Forbidden s h phase space a p e D e c r e a s i n g Excluded c r o s s - s e c t i o n 95% confidence σ m(SUSY mother) e.g. gluino Experimental priority Raise lower mass sensitivity/exclusion * Aka ‘compressed’, ‘squashed’, ‘squeezed’, small mass-splittings SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 9

Tricky: how do we interpret SUSY limits? “ ATLAS SUSY Public @ ICHEP 2016 What do these constraints mean for my favourite BSM model? - anxious model builder friend “ Surely it’s unfair to compare analyses using different simplified models? - wise collider physics friend “ How well do these simplified models probe realistic MSSM scenarios? - natural MSSM advocate friend SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 10

The ATLAS p(henomenological)MSSM ATLAS [arXiv:1508.06608], Berger et al [arXiv:0812.0980], Cahill-Rowley et al [arXiv:1206.4321, arXiv:1211.1981, arXiv:1407.4130] Scan 19-parameter MSSM Vanilla assumptions: R-parity conserved, neutralino LSP, flavour & CP violation only in CKM,… Z width Muon g-2 Non-LHC constraints on 500+ million DM direct DM relic density detection limits pMSSM points upper bound Higgs mass LEP searches B Physics 22 ATLAS 7+8 TeV (up to 20/fb) searches constrain ~310k points ATLAS Collaboration [arXiv:1508.06608 ] 6 ATLAS 13 TeV (3.2/fb) searches constrain ~183k points A Barr & JL [arXiv:1605.09502] MadGraph5 + Pythia6 + Delphes3 + MadAnalysis5 ~3 billion events generated | ~250k CPU hours SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 11

Jesse Liu SUSY pMSSM & Soft | 12 Jan 2016 − 1 Added Run 1 7+8 TeV (up to 20.3 fb ) pMSSM19 H/A 2-tau Fraction of Models Excluded % Models Excluded at 95% CL 1500 1 30 100 Run 1 exclusion: ATLAS [arXiv:1508.06608] Run 2 exclusion: Barr & Liu [arXiv:1605.09502] 0.8 No. of Analyses ) [GeV] 1000 20 0.6 50 0 1 0.4 ∼ χ 500 ( m 10 0.2 0 0 0 0 0 1000 2000 3000 1 Analysis ~ 1.9% ( g ) [GeV] m Impact of 28 SUSY searches on pMSSM19 28 ATLAS SUSY searches applied in following order: Run 1 | electroweak, stops & sbottoms, squarks & gluinos Run 2 | squarks & gluinos. Fractions normalised to 310.3k pre-selected points with long-lived gluinos, squarks & sleptons removed. Raw exclusion info for this is publicly available at Run 1 HEPData [ ATLAS ] and Run 2 up to 3.2 / fb [ Barr & Liu ] . Please download and use Adobe Reader to view animation. 12

Gluino-LSP plane Sub-TeV gluinos generally close to with LSP mass Black = 100% exclusion Lightest supersymmetric particle (LSP DM) TAKE-HOME MESSAGE Simplified model captures gluino sensitivity fairly well Normalised to Run 1 survivors, without long-lived A Barr & JL [arXiv:1605.09502] Exclusion info: www-pnp.physics.ox.ac.uk/~jesseliu/pmssm SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 13

Scatter 28k points excluded by six 13 TeV searches Most sensitive search = lowest CLs value used for exclusion Coannihilators needed for bino-like LSPs LEP chargino lower limit ~ 100 GeV (bounds Higgsino & wino-like LSPs) Bino-like LSPs annihilating through Z or h ‘funnel’ A Barr & JL [arXiv:1608.05379] SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 14

Distinct regions of sensitivity identified Moderately compressed ~ ~ 30 ≲ m(g) - m( χ ) ≲ 200 GeV low sensitivity remains Monojet still Light squarks needed for ultra t e j compressed o n o M 2-6 jets Multi-b Multi-b & 7-10 jets better for larger mass splittings than 2-6 jets 7-10 jets ‘Heavy gluino exclusion’ correlated with light squark sensitivity SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 15

Project into direct detection cross-section vs DM mass Points excluded by LHC Most sensitive ATLAS search Above line ~ excluded WIMP-nucleus cross-section spin-independent normalised by nucleon (present) (future) Relic density saturation factor Reduced by WIMP Direct detection relic density under-saturation limits Recent + future WIMP dark matter mass Xenon-target experiments Neutralino LSP SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 16

THE SEARCHLIGHT IS SHIFTING from spectacular to subtle discoveries Opportunities & challenges for L H C soft, rare, quirky signals Minimality Soft stuff Unification Particle identification Trigger thresholds Naturalness Rare SUSY Colourful states Colourless sparticles Light gluino, stops Dark sector WIMP dark matter Quirky creatures Displaced difficulties Jets + MET searches Long-lived exotica E N E R G Y LUMINOSITY P R I O R I T Y P R I O R I T Y SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 17

Scalar leptons arXiv:1403.5294 *Also phenomenologically motivated Neutralino DM ‘coannihilation’ region ✩ See backup 28-29 for slepton selection Δ M ≲ 3 GeV Δ M ≲ 60 GeV Need low-MET 0/1L Monojet search LEP2 stays best* LH+RH A new hope Δ M ~ 3 → 24 GeV Monojet + 2L + MET mT2 ✩ RH projected LH 100/fb sensitivity only LH [arXiv:1412.0618 , arXiv:1501.02511] only Δ M ~ 24 → 60 GeV Scalar electron/muon ‘slepton’ Usual mT2 kinematic edge ineffective against formidable WW & di-top background SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 18

Scenario: scalar leptons with plentiful phase space Reconstructed MET SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 19

Problem: squished phase space hampers detectability Reconstructed MET SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 20

Solution: boost SUSY system off jet Reconstructed MET SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 21

New triggers enable new searches Lepton pT Problem Shaded area = acceptable trigger rate* Raise thresholds ~20 GeV Single object trigger to keep rates low but miss soft physics Combined trigger Innovation Rare + soft SUSY Exploit signal topology: trigger on multiple objects e.g. j80 mu4 met60 Lumi (& pileup) CMS introduced such triggers for 2016 data-taking [PAS-SUS-16-025] * Experimental bottleneck: limited by e.g. data transfer bandwidth SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 22

S U M M A R Y LHC: testing relativity + quantum theory Need for new data era SUSY remains key search lamppost Interpretation: what do the searches mean? Phenomenological (realistic) 19-parameter MSSM Explore distinct regions of sensitivity Soft physics: experimental challenges Exploit luminosity for tough rare+soft SUSY New detector triggers needed SUSY pMSSM & Soft | 12 Jan 2017 | Jesse Liu | 23

EXTRAS SUSY New & Future | 5 Jan 2017 | Jesse Liu | 24