BSM Searches at LHC after Upgrade Monika Wielers

BSM Searches at LHC after Upgrade Monika Wielers (RAL – STFC) On behalf of the ATLAS, CMS and LHCb collaborations LHCP conference, Shanghai, May 15 -20, 2017 Monika Wielers (RAL)

Introduction LHC physics analysis in full swing with many BSM searches ongoing HL-LHC will further increase luminosity from 300 fb-1 to 3000 fb-1 for ATLAS/CMS HL-LHC BSM physics provides Increased window in finding new physics Direct observation of new phenomena Indirectly via deviations from SM expectations Probing new phenomena observed in Run-2 or Run-3 Better understanding of underlying physics Rare processes, weaker couplings, anything needing lots of statistics Ensure that the planned upgraded detectors can do all of this well Will show today selected examples from our recent benchmark physics analyses from ATLAS, CMS, LHCb 21/09/2021 Monika Wielers (RAL) 2

HL-LHC Plan Exp. Peak luminosity Mean number of inter- Integrated (cm-2 s-1) actions per BC <μPU> luminosity (fb-1) ATLAS Baseline 5 × 1034 140 3000 /CMS Ultimate 7. 5 × 1034 200 LHCb Run-3/4 2 × 1033 2. 5 15 (50) Run 3 (4) Run-5 2 × 1034 50 300 21/09/2021 Mode Monika Wielers (RAL) 3

HL-LHC Challenges for experiments Very high pileup Intense radiation Major experiment upgrades needed to Improve radiation hardness and replace detectors at end-of-life Provide handles for mitigating pileup (high granularity, fast timing) ATLAS/CMS will increase tracker coverage to |η|<4 Allow higher event rates to maintain/improve trigger acceptance Maintain or improve over current performance More information on detector upgrade on Fri and Sat morning 21/09/2021 Monika Wielers (RAL) 4

Analysis technique ① Extrapolation from Run-1/2 Assume Run-1/2, improved by fixed factor or no systematic uncertainties ② Use parameterised detector performances on generator information Parameterisation of Detector resolution and pileup effects on e, γ, μ, , jets, ETmiss Reconstruction and trigger/offline identification efficiencies and fake rates (includes also b-tagging) Done mostly in η & p. T/ET bins and extracted using full sim. Can also overlay pileup jets Depending on analysis assume no systematics or systematic uncertainties based on extrapolation Parameterised approach used in examples if not stated otherwise Pileup is <μ> = 200 21/09/2021 Monika Wielers (RAL) 5

SUSY: direct production of stau pairs ~ ATL-PHYS-PUB-2016 -021 ~ Combined ~L~ L + ~ ~ R R production Discovery reach 430 -520 Ge. V (depending on bkg uncertainty) 21/09/2021 ~ ATLAS Run-1 exclusion: m( R)<109 Ge. V Monika Wielers (RAL) 6

ATL-PHYS-PUB-2016 -022 Direct stop pair production with compressed mass spectra ~ ~ Assuming 30% uncertainty on SM bkg Discovery reach 500 Ge. V@3 ab-1 ~ ~ Stransverse mass [Ge. V]: Monika Wielers (RAL) 7

CMS W’➞tb in leptonic final state CMS DP-2016/064 Signature High-p. T lepton, significant ETmiss, 2 b-jets Extrapolation of Run-2 with 13 fb-1 (CMS B 2 G-16 -017) Systematics Run-2 or no systematic uncertainties Reduce most experimental to percent level, top p. T reweighting by factor 3, theory uncertainties by factor 2 Exclusion limit: m(W’) > 4 Te. V 21/09/2021 Current limit: 2. 67 Te. V 8

ATLAS ttbar resonance search ATL-PHYS-PUB-2017 -002 Study Z’➞tt➞ℓνb qq’b Use top-colour Z’ model as benchmark Look at events with high p. T e/μ, large ETmiss, and multiple small-R jets or large-R jet <μ>=200 Muon channel <μ>=200 Exclude this resonance at 95% CL (no systematic uncertainties) with m. Z′ < 3 Te. V after Run-3 m. Z’ < 4 Te. V after the HL-LHC Run-1 paper with 20. 3 fb-1 (JHEP 08(2015) 053): m. Z′ < 2. 1 Te. V 21/09/2021 Monika Wielers (RAL) 9

CMS DP-2016/064 CMS ttbar resonance search Projected results from Run-2 analysis (CMS-PAS-B 2 G-15 -002, CMS-PAS-B 2 G-15 -003) Study both lepton+jet and all hadronic final states Two scenarios for systematic uncertainties considered: Current systematic uncertainties No systematic uncertainties applied (“performance limit”) Γ=1% Current Run 2 syst. Γ=16% No syst. - Limits similar to ATLAS - Similar limits on m(Z’) for both final states 21/09/2021 Exclusion limits with broader resonance few 100 Ge. V higher Monika Wielers (RAL) 10

CMS Dark Matter monojet search Complement direct detection experiments Use simplified models with Axial-vector model: Suppressed in direct detection, complementary sensitivity with LHC Pseudo-vector models: Not accessible to direct detection. Only LHC provides sensitivity CMS DP-2016/064 Spin-1 Spin-0 4 parameters (mmed, m. DM, g. SM, g. DM) Signature Large ETmiss > 200 Ge. V, 1 high-p. T jet, no leptons Main background: Z(νν)+j, W(lν)+j Discriminant ETmiss distribution Extrapolation from 13 Te. V results with 13 fb-1 (CMS-EXO-16037) 21/09/2021 Monika Wielers (RAL) 11

CMS Dark Matter monojet search CMS DP-2016/064 Dominating systematics = understanding ETmiss Scale Run-2 systematics at low ETmiss which are dominated by lepton ID/ISO to HL-LHC, high ETmiss dominated by statistics Pseudo-vector (g. DM=1, g. SM=1) Axial-vector (g. DM=1, g. SM=0. 25) Exclusion of Mmed up to 2. 5 – 3 Te. V (dep. on syst. ) 21/09/2021 Exclusion of Mmed up to 600 – 900 Ge. V (dep. on syst. ) Monika Wielers (RAL) 12

CERN-LHCC-2017 -003 21/09/2021 L = 300 fb-1 Dark photon mass [Ge. V] Phys. Rev. Lett. 116 (2016) 251803 Coupling strength LHCb well suited to probe new physics in low p. T region and has excellent capabilities to reconstruct b and c-hadrons Many BSM theories predict some sort of hidden sector, weakly coupled to visible sector E. g. dark photons (A’): dark sector which couples to SM via dark photon which mixes with the SM γ Look for D*➞D 0 A’, A’➞e+e. A’➞μ+μ- (both prompt and displaced μ’s) Fully data-driven approach, A’ rate inferred from SM prompt μμ spectrum Coupling strength LHCb dark photons For ref: after Run-3 Dark photon mass [Ge. V] 13

Conclusions and Outlook HL-LHC very challenging environment Upgraded detector in most areas designed to match current performance at highest pileup levels and will be even better in some areas Rich BSM physics programme at the HL-LHC Increased physics reach with HL-LHC Selected examples shown More analyses looking for new physics to be shown in talk by M. Vidal Marono and O. Steinkamp this morning Important feedback to detector designs for upcoming TDRs Sensitivity affected by systematics, reducing experimental and theoretical uncertainties will improve the reach of many of these searches 21/09/2021 Monika Wielers (RAL) 14