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Exotics at the LHC: Recent Discoveries and Future Prospects

Delve into the latest findings in the search for exotic particles at the Large Hadron Collider (LHC). Explore diverse topics including New Gauge Bosons, Extra Dimensions, Long-Lived particles, and more. This talk provides insights into the implications of LHC results for TeV-scale physics. Unravel the mysteries of black holes, heavy stable charged particles, and other truly exotic phenomena. Discover the latest advancements and limitations in the quest for new physics beyond the Standard Model.

michelle-dillard
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Exotics at the LHC: Recent Discoveries and Future Prospects

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  1. Exotics at the LHC Sam Harper (RAL, STFC) UK HEP Forum 08/09/11 Sam Harper - Exotics - HEP Forum UK

  2. EXO Searches at LHC correct! (and thanks for inviting me to give this talk Ian  ) • from Ian’s EXO HEP Forum UK talk last year: • Huge number of Exotic results out • ATLAS: 15 papers • CMS: 20 papers • will only focus on results with 2011 data • some interesting results missed sadly • 7 ATLAS, 18 CMS results with 2011 data Sam Harper - Exotics - HEP Forum UK

  3. Exo 2011 Searches see recent “Implications of LHC results for TeV-scale physics” https://indico.cern.ch/conferenceOtherViews.py?view=standard&confId=141983 for a more detailed set of talks • New Gauge Bosons • di-lepton, di-jet, ttbar, di-lepton+di-jet final states, lepton+MET, WZ • Extra Dimensions • di-fermion, di-photon, jet+MET, photon + MET • Long Lived • displaced muons/electrons • stopped gluinos • 4thGeneration fermions • t’, b’, T • The Truly Exotic…. • blackholes, heavy stable charged particles, W+dijet Sam Harper - Exotics - HEP Forum UK

  4. New Gauge Bosons Sam Harper - Exotics - HEP Forum UK

  5. Z’->ee / µµ UK effort both ATLAS + CMS! *ATLAS accxeff quoted at 1.5 TeV but should be similar at 1 TeV • classic discovery channel: • inclusive search: mass of 2 leptons |η|<2.5, no cuts on MET / other activity in event • no OS required eles / OS required muons • excitement earily on this year but sadly died away • no significant excess: • highest in CMS: 970 GeV, local: 2.1sigma • with LEE effect, 0.2 sigma • ATLAS doesn’t quote highest excess, its either ~570 GeV or ~950 GeVwith similar significance to CMS Sam Harper - Exotics - HEP Forum UK

  6. Z’->ee / µµ • classic discovery channel: • inclusive search: mass of 2 leptons |η|<2.5, no cuts on MET / other activity in event • no OS required eles / OS required muons • excitement earily on this year but sadly died away • no significant excess: • highest in CMS: 970 GeV, local: 2.1sigma • with LEE effect, 0.2 sigma • ATLAS doesn’t quote highest excess, its either ~570 GeV or ~950 GeV with similar significance to CMS *ATLAS accxeff quoted at 1.5 TeV but should be similar at 1 TeV Sam Harper - Exotics - HEP Forum UK

  7. Z’->ee / µµ: Limits Z’ SSM limits • limits: • ATLAS/CMS about the same ele • CMS does much better muons • note: CMS missed the cu–cd from this update due to lack of time but will happen for next update Sam Harper - Exotics - HEP Forum UK

  8. 35pb-1 to 1.1fb-1 • Z’->ee/µµ exclusion from 0.05pb to 0.002pb • large jump in sensitivity • thanks LHC! Sam Harper - Exotics - HEP Forum UK

  9. Z’/W’->di-jet • search di-jet resonance • CMS |η|<2.5, |Δη|<1.3, ATLAS, |η|<2.8 |y*|<0.6 • good agreement with data to fit parameterisation • no evidence of any significant excess Sam Harper - Exotics - HEP Forum UK

  10. Z’/W’->di-jet excited quark limits CMS also quotes W’ limit of: 1-1.55 TeV • limits are final state dependent • FSR reduces resolution • gg final states: more FSR, worse resolution, worse limits • ATLAS better jet resolution means they are slightly ahead Sam Harper - Exotics - HEP Forum UK

  11. Z’/W’->dijet: Wide Jets combine into single ‘wide jet’ • inspired by recent jet grooming algos • aim is to improve FSR recovery and therefore resolution • previously used Anti-kT 0.7 jets • wide jet algo starts with anti-kT 0.5 jets • identifies two leading jets • for each of these jets, sums in all surrounding jets in ΔR cone of 1.1 • gg states have more FSR • wide jet algo improves resolution • reduces differences between qq, qg and gg limits Sam Harper - Exotics - HEP Forum UK

  12. Z’->ttbar UK effort on ATLAS here! • top particle can be special in BSM theories • new physics can preferentially couple to it • important channel to study • current analyses: • semi-leptonic • di-lepton modes • fully hadronic (boosted) Sam Harper - Exotics - HEP Forum UK

  13. Z’->ttbar • top particle can be special in BSM theories • new physics can preferentially couple to it • important channel to study • current analyses: • di-lepton modes • semi-leptonic • fully hadronic (boosted) Sam Harper - Exotics - HEP Forum UK

  14. W’->eν / μν • non-resonant signature due to MET • look for excess in high end tail • similar to Z’ analysis, just replace 1 lepton with MET • efficiency: ~80% in both channels • CMS uses particle flow based MET • excellent agreement between SM + data • no hint of any excess in 1fb-1 • see what 2011 dataset offers • set limits using Bayesian cut and count above MT threshold optimized on signal samples Sam Harper - Exotics - HEP Forum UK

  15. W’->eν / μν W’ mass limits • σ.Br limits both very similar • ATLAS slightly better expected, CMS better obs • ATLAS: • ~8fbat 1 TeV to ~10fb at 2.5 TeV • CMS: • ~7fb at 1.4 TeV to ~9fb at 2.5 TeV Sam Harper - Exotics - HEP Forum UK

  16. W’->WZ->3lν, l=e,μ HT Cut for 600 GeV W’ • event selection: • 2 same flavour opposite charge leptons with 60<Mll < 120 • 1 more high pT lepton + MET > 30 GeV • HT cut, optimised for each W’ mass • analysis motivated by technicolor • limits set by Bayesian cut and count technique Sam Harper - Exotics - HEP Forum UK

  17. W’->WZ->3lν, l=e,μ HT Cut for 600 GeV W’ • event selection: • 2 same flavour opposite charge leptons with 60<Mll < 120 • 1 more high pT lepton + MET > 30 GeV • HT cut, optimised for each W’ mass • analysis motivated by technicolor • limits set by Bayesian cut and count technique Sam Harper - Exotics - HEP Forum UK

  18. WR + Heavy Neutrino • searches for WR to heavy ν predicted by L-R SM extension • require 1 lepton > 60 GeV • accxeff: 50% ele, 60% muons Sam Harper - Exotics - HEP Forum UK

  19. Planck TeV Bulk (y) Extra Dimensions Sam Harper - Exotics - HEP Forum UK

  20. Di-Photon UK effort on ATLAS here! RS Graviton Mass Limits (TeV) • favoured channel for ED • factor 2 high BR to photons over eles/muons • requires two photons with ET > 70 GeV, |η|<1.44 • data driven background estimates of jet background • di-photon background from pythia reweighted by mass dependent NLO k-factor from DIPHOX+GAMMA2MC • searches for both warped (resonant) and ADD (non-resonant) scenarios Sam Harper - Exotics - HEP Forum UK

  21. Mono Jet UK effort on ATLAS + CMS! • searches for jet + MET • benchmark model: ADD extra dim • main background: Z->νν+ jets • estimate from Z->μμ + jet events • limits are cut and count above optimised jet/ MET thresholds Sam Harper - Exotics - HEP Forum UK

  22. Mono Photon • searches for γ + MET • pho ET > 95 GeV, |η|<1.44 + MET> 80 GeV • benchmark model: ADD extra dim • main background: Z->νν+γ • estimate direct from MC • estimate jet backgrounds from data Sam Harper - Exotics - HEP Forum UK

  23. fourth family Sam Harper - Exotics - HEP Forum UK

  24. t’->bW • search for t’t’ ->bWbW • iettbar search but with higher mass • done in lepton+jets, di-lepton channels • uses mass techniques used in top mass methods Sam Harper - Exotics - HEP Forum UK

  25. t’->bW • limits set using CLS method on measured mass spectra • t’ mass limit: • dilepton: 422 GeV • lepton + jet: 450 GeV Sam Harper - Exotics - HEP Forum UK

  26. T->tZ • search for vector like charge 2/3 quark decaying to tZ • can appear in UED, composite Higgs models, Little Higgs • signature: • Z->ee/μμ + 1e/μ + 2 jets • eles > 20 GeV, jets > 25 GeV, muons > 15 GeV • search variable: • ST = Σ jet + leppT • cut ST > 80 GeV • total acc: • 14-35% from 250 to 550 GeV Sam Harper - Exotics - HEP Forum UK

  27. b’->tW • signature: • 2 same sign leptons + 2 jets (1 b-tag) • 3 lepton (2 opp sign) + 1 b-tag jet • looks for excess in ST distribution Sam Harper - Exotics - HEP Forum UK

  28. Long Lived Sam Harper - Exotics - HEP Forum UK

  29. Displaced leptons UK effort on CMS here! from MC cosmic data data / MC difference leads to 20% uncertainty on disaplace track eff • search for neutral objects decaying to ele/mu pairs • eg H0-> 2X, X->l+l- • look for tracks with large transverse impact parameter Sam Harper - Exotics - HEP Forum UK

  30. Displaced Leptons estimate backgrounds from extrapolation of decay length significance • signal selection: • high transverse impact cut significance • pT > 38 GeV (ele), 25 GeV (mu) • have dedicated trackless triggers • muons: expect 0, obs 0 • electrons: some bkg around Z Sam Harper - Exotics - HEP Forum UK

  31. Stopped SUSY UK effort on CMS here! • looks for long lived particles stopping in CMS • specifically the central region of HCAL • 40-50% gluinos, 30-20% stops stop • trigger on 50 GeV jets when there is no beam • main bkgs: beam halo, comics, detector noise • cuts reduce event rate to O(10-5 Hz) • 12-13% efficient for stopped particles • probes lifetimes from 75ns to ~2 weeks Sam Harper - Exotics - HEP Forum UK

  32. Exotic Exotics Sam Harper - Exotics - HEP Forum UK

  33. Same Sign Muon Pairs • a catch all exo search • same sign di-lepton signatures come from variety of models • main motivation is double charged Higgs • searches for two SS muons, pT > 20/10 GeV, |η|<2.5 • sets model independent limits total cross-section above mass M Sam Harper - Exotics - HEP Forum UK

  34. W+2jets • follow up on the CDF bumpusing cuts as close as possible to CDF • no excess observed Sam Harper - Exotics - HEP Forum UK

  35. Blackholes UK effort on ATLAS here! CMS UK also starting out 9 jet candidate with ST =2.6 TeV • searches for high ST events • ST: ΣpT of all objects > 50 GeV in event (including MET) • low multiplicity (N=2,3) control region • ST shape of QCD bkg independent of number of final state objects • fit to this region to get bkg shape • search for new physics in high multiplicity region (N>3) Sam Harper - Exotics - HEP Forum UK

  36. Blackholes no evidence of any signal set limits on various black hole types Sam Harper - Exotics - HEP Forum UK

  37. Summary • CMS + ATLAS have produced many many exotic searches for new physics • huge phase space explored where new physics could have been lurking • no significant deviation seen in any channel • slightly concerning • but on other hand shows we understand our detectors very well • but good news: the LHC is delivering lots of lumi, our detectors are working perfectly • all we need now is nature to be kind to us  (and to make sure we trigger on it…) Sam Harper - Exotics - HEP Forum UK

  38. References • for much more information please see: • https://twiki.cern.ch/twiki/bin/view/AtlasPublic/ExoticsPublicResults • https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsEXO Sam Harper - Exotics - HEP Forum UK

  39. Backups Sam Harper - Exotics - HEP Forum UK

  40. Z’->ττ EXO-10-022 • actively being worked for 2011 • stay tuned… • low backgrounds but complicated final state • acceptance: of order ~15% at 1 TeV over all channels • MET in final state means Z’ is wide, signal will not be as clear cut as in light leptons • Bayesian binned likelihood for limits Sam Harper - Exotics - HEP Forum UK

  41. W’->eν / μν • non-resonant signature due to MET • look for excess in high end tail • similar to Z’ analysis, just replace 1 lepton with MET • 0.4 < pT/ ETmiss<1.5 , Δϕ > 2.5 • acceptance: 80% in both channels • excellent agreement between SM + data • no hint of any excess in 1fb-1 • see what 2011 dataset offers • set limits using Bayesian cut and count • exclusion W’ up to 2.27 TeV Sam Harper - Exotics - HEP Forum UK

  42. W’/Z’ Summary *limit at 0.9 TeV Sam Harper - Exotics - HEP Forum UK

  43. e*/μ* arXiv:1107.1773 • searches for excited states of composite fermions with scale Δ • pp->ll*->llγ • update in progress for 2011 Sam Harper - Exotics - HEP Forum UK

  44. Leptoquarks • search for pair production of lepto quarks • not yet updated to 2011 data • search in following channels: • eejj, μμjj, eνjj • no excess is found Sam Harper - Exotics - HEP Forum UK

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