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Prospects for New Physics at the LHC

atlas. Prospects for New Physics at the LHC. Ayana T Arce APS/AAPT Meeting February 13, 2010. Outline. New physics at the LHC Looking for new physics with ATLAS and CMS The art of the search Possible discoveries using leptons, jets and lifetimes Outlook. New physics (to us).

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Prospects for New Physics at the LHC

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  1. atlas Prospects for New Physics at the LHC Ayana T Arce APS/AAPT Meeting February 13, 2010

  2. Outline • New physics at the LHC • Looking for new physics with ATLAS and CMS • The art of the search • Possible discoveries using leptons, jets and lifetimes • Outlook New Physics @ LHC

  3. New physics (to us) us us Bullet;Chandra Abell 2218; NASA/STSci TeV-scale: age less than 1 picosecond (very old physics!) New Physics @ LHC

  4. new physics with theLarge Hadron Collider <1 inelastic interaction per crossing expected in early 2010 ATLAS CMS 3.5 TeV 3.5 TeV bunches can cross every 25 ns (small fraction filled in early 2010 ) cosmics, beam halo gaps up to 3μseven in 2808x2808 mode New Physics @ LHC

  5. new physics with theLarge Hadron Collider How will the reduced energy for proton beams affect sensitivity? unfavorable BG scaling Quigg arXiv:0908.3660 Bauer et. al arXiv:0909.5213v2 Studies in this talk: 10 and 14 TeV simulation New Physics @ LHC

  6. seeing new physics withATLAS and CMS rare in SM collisions: missing energy ? but we might also “see” a dark matter candidate • neutral, invisible, stable  missing transverse momentum (MET) and we can’t rule out new nearly-stable interacting (or late-decaying) particles • new = heavy, so slow to arrive at a sensor Mostly looking for ~stable SM particlesfrom exotic decays e rare: isolated leptons ubiquitous: jets (quarks/gluons made anonymous) • optimize efficiency, ‘fake’ rate, energy resolution for e, Υ, μ, jets New Physics @ LHC

  7. muons seeing new physics withATLAS and CMS e,γ,jets Q≠0 • ATLAS (pixel/strip sensors + straw transition radiation tracker) • TRT sensitive toβ(e/πseparation) • toroidal µ spectrometer • combined ID+ µ: σ(pT)≈5% (prompt µ from 1-TeV resonance) • CMS: (pixel/strip sensors) • solenoidal µ spectrometer • combined tracker+muonpT resolution ≈5% @1 TeV CERN-OPEN-2008-020; JINST 3:S08003 B=2T R=11m B=4T R=7.5m JINST 0803:S08004 New Physics @ LHC

  8. muons seeing new physics withATLAS and CMS e,γ,jets Q≠0 • LAr + Cu accordion EM calorimeter: • σ(E)/E≈1% for 100 GeV e • fine strip granularity (.003 inη) • 3 samplings: 4.3,16, 2 X0 in barrel • Fe + scintillating tile hadronic calorimeter: • resolution at 1 TeV: 3% • PbWO4 crystal EM calorimeter: • σ(E)/E≈0.5% for 120 GeV e • (0.0175)2η×ϕgranularity • Cu +scintillatorhadronic calorimeter: • resolution at 1 TeV: 6% 3 longitudinal segments CERN-OPEN-2008-020; JINST 3:S08003 JINST 0803:S08004 New Physics @ LHC

  9. The art of the search • Tevatron m(squark, gluino) limits: ~300-400 GeV • m( )> 149 GeV if short-lived • Z’-like resonances not seen below ~1 TeV • Large extra dimensions scale > 1 TeV (N>4) • SM is “unknown” in p+p @7 TeV • choose between model+luminosityor ‘sideband extrapolation’ uncertainty • absolute jet calibration: statistics+time (ϒ,Z+jets): • uncertainties affect efficiency (degrade limits) , • and background rejection (reduce significance) know your limits… &limitations New Physics @ LHC

  10. The art of discovery Data-driven background methods (cf. sideband subtraction) • inclusive searches: greater challenge to prove backgrounds are understood • Beware bias from presence of signal (blunted sensitivity) CMS PAS EXO-08-011 ATL-PHYS-PUB-2009-083 New Physics @ LHC

  11. Searches dilepton resonances tt resonances extra dimensions supersymmetry lifetime signatures New Physics @ LHC

  12. early probes of new physics:searching for dilepton pairs e,μ • dilepton resonances are generic to many models: • GUTs, little Higgs, technicolor, Randall-Sundrum gravitons… • Background : predominantly Drell-Yan • top, diboson: ~10% at higher mass • Sensitivity depends strongly on mass resolution e, μ Drell-Yan parameterization ee: 14 TeV CERN-OPEN-2008-020 CMS PAS EXO-09-006 μetechnique New Physics @ LHC

  13. early probes of new physics:searching for dilepton pairs CERN-OPEN-2008-020 μμ14 TeV CMS 100pb-1 @ 10 TeV CMS PAS EXO-09-006 New Physics @ LHC

  14. understanding the large top mass:looking for tt resonances tWb • can we explain mT ~ 175 GeV by enhanced couplings (Topcolor Z’; R-S with bulk fermions)? • Challenges: top identification; mass reconstruction with top quarks ATL-PHYS-PUB-2009-081 2&3 TeV jets (heavy flavor) Tags: jet mass secondary vertex tag kT-like splitting scale non-isolated muon angular separation decreases with energy escaping neutrinos New Physics @ LHC

  15. understanding the large top mass:looking for tt resonances EXO-09-008 tWb CMS semileptonic: ~4% signal efficiency @ 1 TeV ATLAS: strong rejection for 2 TeV Z’ search CMS all-hadronic ‘double tags’ signal efficiency 0.34% @ 1 TeV CMS PAS EXO-09-002 1 fb-1 10TeV ATL-PHYS-PUB-2009-081 100pb-1 New Physics @ LHC ATLAS 14TeV

  16. some searches for hidden dimensions:BH events • effects of strong gravity at distances ≤ 1/TeV: • black holes or stringballs(democratic decay to a large number of objects per event) Cuts: 4 high-pt objects and a lepton Black holes 14 TeV CERN-OPEN-2008-020 • High pT objects (>200 GeV): • pass single jet triggers without prescale New Physics @ LHC

  17. some searches for hidden dimensions:BH events • effects of strong gravity at distances ≤ 1/TeV: • black holes or stringballs(democratic decay to a large number of objects per event) stringballs 10 TeV • High pT objects (>200 GeV): • pass single jet triggers without prescale ATL-PHYS-PUB-2009-011

  18. some searches for hidden dimensions:gG events • graviton+jet signature: “monojet” • collision backgrounds: • invisible Z+jet • top/single top: reducible • “invisible W,” Wtau • also contaminated by cosmic rays, beam halo 14 TeV CMS PAS EXO-08-011 • Z/Winvisible background: normalize to Wmuon New Physics @ LHC

  19. sparticles and dark matter:inclusive SUSY searches Lead jet: 100-180 GeV missing E(T): ~ 0.3*M(Eff) • Typically heavy squarks/gluinos cascade to LSP: • energetic SM particles emitted at each decay • large missing energy from dark matter candidate • 600-700 GeV squark/gluino masses accessible with 200 pb-1  ttbar-like events ~40-50 GeV jets 20 GeV leptons ATL-PHYS-PUB-2009-084 New Physics @ LHC

  20. sparticles and dark matter:GMSB signature: nLSP • ~50 GeV photon trigger • (or multi- jets) • Photon “tracking” without conversions • measure lifetime via displacement + TOF CERN-OPEN-2008-020 few cm displacement # photons New Physics @ LHC

  21. other long-lived signatures:charged massive particle ID TRT high-threshold hits • charge allows velocity measurement by time of flightand ionization CERN-OPEN-2008-020 signal BG 10 TeV CMS PAS EXO-08-003 tracker dE/dx drift tube TOF New Physics @ LHC

  22. working overtime:searching for split SUSY collisions • R-hadrons can stop in the detector material • Note axis units! Uncertainties: • gluino production model • exotic stopping power of CMS • LHC operations stopping probability quiet time CMS PAS EXO-09-001 New Physics @ LHC

  23. Outlook • New (timely!) theory ideas, bigger backgrounds, new experimental challenges: • analyses are maturing before high-energy data arrives • This was a truncated overview: • the first discovery may not be in these slides… it may show up as something entirely unexpected! New Physics @ LHC

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