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2. LHC 2 The LHC offers the opportunity to search for physics beyond the Standard Model (BSM) by opening a new energy frontier Higgs boson discovery in 2012: the SM is complete Standard Model has survived decades of experimental tests … but open questions remain such as origin of mass, neutrino oscillations, matter-antimatter asymmetry, the nature of DM and DE, how to incorporate the General Relativity and many others To explain the deficiencies of SM new physics proposals would modify the SM in order to be consistent with existing data.

3. 3 Inner Detector (ID) for tracking: semiconductors (pixel and SCT) and transition radiation tracker (TRT) Super conductive solenoid encloses the ID. It produces 2T uniform magnetic field along z Sampling-based calorimeters: lead+liquid Argon for EM energy (ECAL), steel+scintillator for Hadronic energy (HCAL), copper/tungsten+liquid argon in the forward calorimeter (FCAL) Muon Spectrometer (MS): one barrel and 2 end-cap air-core toroidal magnetic field (4T) to bend muon tracks in η Detector performance (E, p T in GeV) z y x p p

4. 4 ATLAS results shown in this talk refers to 7+8 TeV collisions recorded in 2011 and 2012: collisions at √s = 8 TeV ~20 interactions per crossing 20.3 fb-1 collected good for physics collisions at √s = 7 TeV ~9 interactions per crossing 4.6 fb-1 collected good for physics ATLAS performance close to or exceeding design specs in all compartments Efficiencies for 2012 data tacking

5. 5 Strategy: Define selection based on signal signatures and background (bkg) kinematics Compare data to Standard Model bkg (Monte Carlo (MC) + data driven) and MC signal predictions → data consistent with bkg+signal would be evidence for new physics Complete list of results is summarized at https://twiki.cern.ch/twiki/bin/view/AtlasPublic No evidence for new physics: Limits typically set on cross-section x branching fraction (σ x BR) Comparisons provided for specific models, but usually possible for reader to constrain additional models This talk presents results of some specific BSM searches focus on the most recent ones personal choice among tens of results carried out in the ATLAS SUSY and Exotics groups

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7. 7 Why SUSY? Solves the hierarchy problem Provides the dark matter candidate: if R-parity is conserved, lightest SUSY particle (LSP, neutralino) is stable Extends the Poincare group, provides unification with gravity Required for the string theory … and more others … Global symmetry between fermions & bosons: all SM particles have SUSY partners Q|fermion> = |boson> Q|boson> = |fermion> s SUSY = s SM -1/2 R = (-1) 2s (-1) 3B (-1) L

8. 8 Electroweak gluinos/squarks third generation Production modes Strong Final state signatures R-parity conservation R-parity violation Long lived particles Stable LSP (MET, DM?) LSP decays (SM particles) Sparticles lifetime (displaced decays)

9. 9 Lower production cross‐section but Less hadronic activity (trigger on leptons) Light charginos/neutralinos Light sleptons Many production modes and final states explored in Run1: no excess was found

10. 10 Gluinos cascade with gravitino, Z, photon and jets in the final state See [arXiv: 1507.05493] Photon trigger E t miss dφ between jet/γ and E T miss Search for photonic signatures of this Gauge Mediated SUSY (GGM) M(gluino) lowerlimit @~1140GeV for higgsino-bino NLSP

11. 11 Squarks will decay in cascades to final states with jets See [arXiv: 1507.05525] CERN-PH-EP-2015-162 for summary results lepton (e or μ) veto E t miss dφ between jet and E T miss

12. 12 Recent ATLAS summary paper on run 1 searches about third generation squarks [arXiv: 1506.08616] Many analysis targeting various decay topologies Lower limits on stop mass up to 800GeV Use the azimuthal angle distribution between the two leptons in the dileptonic events to probe the difficult region where the mass of the stop is closed to that of the top [arXiv:1412.4742] MET jets leptons b-jets

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14. 14 New strong dynamics and Extra Dimensions Alternative to super-symmetric explanations of electroweak symmetry breaking Often accompanied by heavy new states with integer spin Left-right symmetric and Extended gauge models with spin-1 states Randall-Sundrum (RS) models with heavy spin-2 states Experimental strategy: Signature-based searches benchmarked with reference models Increasing emphasis on limiting model dependence

15. 15 Pairs of isolated muons Dominant background is Z/γ* ll No excess observed New Interpretations for limit setting on grand-unification model based on the E6 gauge group, Z ∗ bosons, Technicolor, etc. [arXiv:1405.4123] Phys. Rev. D. 90, (2014)

16. 16 [arXiv:1407.7494] JHEP09 (2014) 037 Isolated electron or muon plus ETM Dominant background is W lν No excess observed New Interpretations for limit setting on SSM W' and W*

17. 17 [arXiv:1406.4456] Phys.Lett.B 737 (2014) Four decay channels are considered: eνee, μνee, eνμμ, μνμμ Exactly 3 charged leptons are selected No excess observed New Interpretations for limit setting on extended gauge W’ and Heavy Vector Triples models

18. 18 (Some) motivations Excess of positron flux in cosmic rays (not anti-proton) → if DM annihilates to a hidden sector it would produce leptons (g s -2) μ anomaly: comparing theory to experiment there is a 3.2σ discrepancy → anomaly can be explained including corrections from an hidden photon The portal to hidden sector can be Higgs or super-symmetric particles If the produced hidden particles have mass O(1GeV) (e.g. the dark-photon) they can decay back to SM to collimated pair of leptons (LJ) Dark-photon lifetime depends on the size of the kinetic- mixing ε: small values correspond to long lifetime and then displaced decay vertex. The BR of the dark-photon to leptons depends on its mass. Several BSM models predict final states containing Lepton-Jets Kinetic mixing [arXiv:1409.0746] JHEP 11 (2014) 088

19. 19 Model-independent search strategy starting from a general non-prompt LJ definition: LJ: N (≥1) long-lived neutral light objects (dark photons γ d ’s) in a narrow angular cone ΔR decaying to pairs of electrons/muons/pions → lepton/hadron pairs in a narrow cone ΔR Non-prompt LJ: LJ produced by long-lived γ d ’s (small ε) → displaced decays highly isolated in ID LJ reconstruction LJ with only muons: ≥2 muons clustered in a ΔR=0.5 cone and NO jets in the cone LJ with muons and electrons/pions: ≥2 muons + jets clustered in a ΔR=0.5 cone LJ with only electrons/pions in HCAL: jets with low EM fraction and narrow width multi-muon trigger + calorimeter jet trigger >1 LJ per event A LJ gun MC generator has been developed to optimize search criteria and to produce detection efficiency curves to constrain theory models predicting LJ production Opening ∆R between the two muons in a LJ produced by the decay of a single γd. Event selection [arXiv:1409.0746] JHEP 11 (2014) 088

20. 20 No excess of events observed over the estimated background → set limits on specific models ATLAS results in the (ε,m) exclusion plane as σ×BR limits Number of events 2012 DATA119±11 (stat) Cosmic-rays40±11 (stat) QCD (data driven)70±58 (stat) Total background110±59 (stat) Results of LJ analysis selection Benchmark model: Falkowsky-Ruderman- Volansky-Zupan Higgs boson decay to LJ FRVZ modelexcluded cτ [mm] BR(10%) expected event at cτ 47 mm BR(10%) Higgs → 2γ d + X14 ≤ cτ ≤ 14060 ± 7 (stat) Higgs → 4γ d + X15 ≤ cτ ≤ 260104 ± 9 (stat) [arXiv:1409.0746] JHEP 11 (2014) 088

21. 21 An enormous variety of searches undertaken during LHC run 1 covering many different production and decay modes and final states No evidence for physics beyond the SM during run 1 -> experiments have published many exclusion limits, continuing to constrain the parameter space of many physics models BSM While we complete the Run 1 program, eagerly awaiting data at higher energy Searches for high-mass objects will be more sensitive with only a few fb −1 New challenges to meet with higher energy, luminosity: Increased emphasis on boosted topologies Sensitivity to rare SM processes as backgrounds

22. 22 https://twiki.cern.ch/twiki/bin/view/AtlasPublic/SupersymmetryPublicResults

23. 23 https://twiki.cern.ch/twiki/bin/view/AtlasPublic/ExoticsPublicResults

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26. 26 Jet: cluster in EM and hadronic calorimeters (and Inner Detector) Photon: EM cluster without matching track into ID Electron: EM cluster with matching track into ID Muon: matching tracks in inner and muon trackers; the standalone muon is the segment into the MS Tau: Narrow jet with matching track(s) MET (missing ET): p T required to balance all of the above (and more) Jet Photon Electron Muon Tau MET (missing ET)

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