BSM searches SUSY and Exotic from ATLAS 7

BSM searches (SUSY and Exotic) from ATLAS 7 th High Energy Physics International Conference Madagascar-Antananarivo, 17 -22 th September 2015 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 1

The SM as of LHC run 1 Higgs boson discovery in 2012: the SM is complete • • The LHC offers the opportunity 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. LHC to search for physics beyond the Standard Model (BSM) by opening a new energy frontier 2 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration

The ATLAS detector y x z • • p • Inner Detector (ID) for tracking: semiconductors (pixel and SCT) and transition radiation tracker (TRT) Super conductive solenoid encloses the ID. It produces 2 T 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 (4 T) to bend muon tracks in η Detector performance (E, p. T in Ge. V) 3 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration

The ATLAS data taking ATLAS results shown in this talk refers to 7+8 Te. V collisions recorded in 2011 and 2012: • collisions at √s = 8 Te. V • ~20 interactions per crossing • 20. 3 fb‐ 1 collected good for physics • collisions at √s = 7 Te. V • ~9 interactions per crossing • 4. 6 fb‐ 1 collected good for physics Efficiencies for 2012 data tacking ATLAS performance close to or exceeding design specs in all compartments M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 4

Searches for new Physics 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 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 Complete list of results is summarized at https: //twiki. cern. ch/twiki/bin/view/Atlas. Public M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 5

SUSY searches 6 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration

SM plus SUSY 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)2 s(‐ 1)3 B(‐ 1)L 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 … M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 7

SUSY search at ATLAS Production modes Electroweak Strong gluinos/squarks Final state signatures R‐parity conservation third generation Stable LSP (MET, DM? ) R‐parity violation LSP decays (SM particles) Long lived particles Sparticles lifetime (displaced decays) M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 8

EW SUSY (≥ 2 leptons (e, ( μ, τ) + Etmiss) Lower production cross‐section but Less hadronic activity (trigger on leptons) Light charginos/neutralinos Light sleptons Many production modes and final states explored in Run 1: no excess was found M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 9

Strongly produced SUSY Gluinos cascade with gravitino, Z, photon and jets in the final state Search for photonic signatures of this Gauge Mediated SUSY (GGM) Photon trigger Etmiss dφ between jet/γ and ETmiss See [ar. Xiv: 1507. 05493] M(gluino) lowerlimit @~1140 Ge. V for higgsino‐bino NLSP M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 10

Strongly produced SUSY Squarks will decay in cascades to final states with jets lepton (e or μ) veto Etmiss dφ between jet and ETmiss See [ar. Xiv: 1507. 05525] CERN‐PH‐EP‐ 2015‐ 162 for summary results M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 11

Third generation SUSY Many analysis targeting various decay topologies Lower limits on stop mass up to 800 Ge. V • • MET jets leptons b‐jets 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 [ar. Xiv: 1412. 4742] 12 Recent ATLAS summary paper on run 1 searches about third generation squarks [ar. Xiv: 1506. 08616] M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration

Exotic searches 13 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration

BSM heavy bosons 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 14 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration

Search for high-mass dilepton resonances (8 Te. V, 20. 3 fb-1) [ar. Xiv: 1405. 4123] Phys. Rev. D. 90, (2014) 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 E 6 gauge group, Z∗ bosons, Technicolor, etc. M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 15

Lepton + ETmiss high mass states (8 Te. V, 20. 3 fb-1) [ar. Xiv: 1407. 7494] JHEP 09 (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* M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 16

WZ resonances (8 Te. V, 20. 3 fb-1) [ar. Xiv: 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 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 17

Lepton-Jets [ar. Xiv: 1409. 0746] JHEP 11 (2014) 088 Several BSM models predict final states containing Lepton‐Jets The portal to hidden sector can be Higgs or super‐symmetric particles Kinetic mixing 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. If the produced hidden particles have mass O(1 Ge. V) (e. g. the dark‐photon) they can decay back to SM to collimated pair of leptons (LJ) • (Some) motivations • • Excess of positron flux in cosmic rays (not anti‐proton) → if DM annihilates to a hidden sector it would produce leptons (gs‐ 2)μ anomaly: comparing theory to experiment there is a 3. 2σ discrepancy → anomaly can be explained including corrections from an hidden photon M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 18

Non-prompt Lepton-Jet search (8 Te. V, 20 fb-1) [ar. Xiv: 1409. 0746] JHEP 11 (2014) 088 Model‐independent search strategy starting from a general non‐prompt LJ definition: • LJ: N (≥ 1) long‐lived neutral light objects (dark photons γd’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 γd’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 Event selection • • • 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 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration Opening ∆R between the two muons in a LJ produced by the decay of a single γd. 19

Non-prompt Lepton-Jet search (8 Te. V, 20 fb-1) [ar. Xiv: 1409. 0746] JHEP 11 (2014) 088 Results of LJ analysis selection Number of events 2012 DATA 119± 11(stat) Cosmic-rays 40± 11(stat) QCD (data driven) 70± 58(stat) Total background 110± 59(stat) No excess of events observed over the estimated background → set limits on specific models Benchmark model: Falkowsky‐Ruderman‐ Volansky‐Zupan Higgs boson decay to LJ ATLAS results in the (ε, m) exclusion plane as σ×BR limits FRVZ model excluded cτ [mm] BR(10%) Higgs → 2γ d + X 14 ≤ cτ ≤ 140 Higgs → 4γ d + X 15 ≤ cτ ≤ 260 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration expected event at cτ 47 mm BR(10%) 60 ± 7(stat) 104 ± 9 (stat) 20

Summary 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 21 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration

SUSY grand summary https: //twiki. cern. ch/twiki/bin/view/Atlas. Public/Supersymmetry. Public. Results M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 22

Exotic grand summary https: //twiki. cern. ch/twiki/bin/view/Atlas. Public/Exotics. Public. Results M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration 23

Spares 24 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration

The ATLAS detector 25 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration

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

Luminosity and pileup 2015 27 M. Schioppa – INFN Cosenza on behalf of ATLAS Collaboration