ATLAS Results M. Cobal, INFN & University Udine PART II XXIV SEMINARIO NAZIONALE

1. ATLAS Results M. Cobal, INFN & University Udine PART II XXIV SEMINARIO NAZIONALE di FISICA NUCLEARE E SUBNUCLEARE OTRANTO, Serra degli Alimini, 21-27 Settembre 2012

2. Why Mtop and MW are interesting? Mtop , MW and EW precisionmeasurements = cross check of SM and constrainMH EW fitdominatinguncertainties: ΔMtopand ΔMW For ΔMWnot to be the dominanterror in the EW fit: ΔMW ∼ 0.007ΔMtop

3. EWK fit Extending the concept to a BSM framework, • Privatecommunication M. Grünewald: • addingmH=125 ± 2 GeV to the EWK fit: • gives χ2 / Ndf = 17.95 / 14, Prob = 20.9%

4. Key SM background processes

5. The typicalanalysis • Design a selectionat a givenmass maximizingan estimator (egs/√bkg). Oftencutting the phase-spacein manyregions • Compute the expectedSM background from control samples, side bands, etc.. also with the help from MC simulation (shapes). Assessthe systematicerror. • Evaluatethe signalefficiencyusingSM Higgs MC simulation • Compute with statisticalmethodsthe largestsignalcross sectiononecan accommodatein the data.

6. The typical plot • Analysesoptimized for exclusion.Theresultisexpressedat a given mass asexclusionat 95% of a cross section • The excluded cross sectioniscomputed in unit of SM cross section (μ). • Expectedsensitivity: measureshowperformingis the analysis • The coloredbandsgivethe expected • statistical⊕systematicvariationof the • resultwrtto the “expected” • Nearbypoints are correlateddependingon the mass resolution

7. H →gg • Separation of g-po in Lar Calo • gpointing to locate primaryvertex • Composition of gg sample: • 75-80% QCD ggproduction • 20-25% g-jet or jet-jet, jet • mis-ID eg due to hard p0

8. H →gg

9. H →ZZ*→4 leptons (e,m) Golden channel: feweventsbut small background. Good mass resolution

10. H →WW*→enmn

11. CombinedSignificance

12. Significance of the p-value • 5.9 (ATLAS) and 4.9 (CMS) σexcess • Impressive consistencybetween7TeVand8TeVdata

13. The LHC discovery Heinemeyeret al, Implicationsof LHC resultsfor TeV-scale physics: signalsof electroweaksymmetrybreaking, Submittedto the Open Symposium of the EuropeanStrategyPreparatoryGroup. A=ATLAS C=CMS √ = channelanalyzed most of the LHC sensitivitycomes from

14. The LHC discovery ATLAS and CMS: significancedriven by the γγ, ZZ and WW channels Besidesthe excessat 125-126 GeV: 95% CL exclusion of a SM-likeHiggs up to ~600 GeV

15. Properties of the new boson • Mass • spin and parity ( JP ) • CP (even, odd, or admixture?) • couplings to vectorbosons: isthisbosonrelatedto EWSB, and howmuchdoesitcontributeto restoringunitarity in WLWL scattering • couplings to fermions • - isYukawainteractionat work? • - contribution to restoring unitarity? • couplings proportional to mass ? • isthereonlyonesuch state, or more? • elementary or composite? • self-interaction

16. Signal strenght

17. Mass vs Signal strenght • Mass compatibilitybetweendifferentchannelsestimatedwith2Dlikelihood, fittingsimultaneouslyμandmHineachchannel • ProbabilitythatasinglebosonproducesmasspeaksinH→γγ andH→4l separatedbymorethantheamountobservedis20% • Massmeasurement: performedusingprofilelikelihoodratiowithmHfloating(channelsused: H→γγ andH→4l withseparateμparameters) • Mainsystematicsfromenergyscale expectedprecisionat the LHC: ~100 MeV expectedprecisionat a linear collider: ≾ 40-50 MeV

18. arXiv:1208.4018v1 [hep-ph JP and CP • STATUS AND QUESTIONS: • decay to twophotons: cannot be spin 1 (Landau-Yang theorem) • JP: currentlytestedat the LHC, usingangularcorrelationsin ZZ*, WW* and γγ • JP: by end of 8 TeV run, assuming 35/fb per exp: • ~4 σseparation of 0+ vs 0- and 0+ vs 2+ • CP: more tricky, basic question of possible mixture of CP-even and CP-odd • If focus at LHC stays on WW*, ZZ* and VBF: limited sensitivity to distinguish pure CP-even state from admixture CP-even / CP-odd • Linear collider: threshold behaviour of e+e-→ttHgives precision measurement of CP mixing. JP: LHC 2012 prospects for 35/fb per exp.

19. Projections coupling scale factors: 5-10% with 300/fbat 14 TeV ratios of partialwidths: 5-30%, for luminosities up to 3/ab very rare channels H→μμaccessibleat the 20% level, with a HL-LHC Higgsself-coupling (double-Higgs production): currentlyunder study. 3σ/exppossibleat HL-LHC, and 30% prec. on λHHHpossibleif more channelsadded and exps. combined

20. Beyond the SM • I The fundamental symmetries: • Are there more general symmetries than SU(3)C SU(2)L U(1)Y? • Of course we will be happy to include the gravity in the extend theory. • Astrophysics observations: • - Neutrino oscillations • - Dark matter • - Dark Energy • The standard model problems: • - Higgs NO  unitarity violation • New interactions to cancel this amplitude; • - Higgs YEShierarchy problem for the higgs mass Pf <L

21. Supersymmetry

22. Minimal MSSM

23. Minimal Supersymmetric Standard Model

24. ATLAS SUSY strategy Search in every corners of the SUSY phasespace

25. Status of SUSY searches 1. Inclusive searches 2. Natural SUSY 3. Long livedparticles 4. RPV

26. Minimal Supersymmetric Standard Model SUSY theoryphasespace MSSM: 29 sparticles+5 Higgsundiscovered Goal: findhints of (N)MSSM particles in the 100 GeV – 1 TeVrange

27. Status of exotic searches

28. Conclusions • Probed a wide variety of SUSY – motivatedfinalstates • Nothingfound so far, butdevelopeddetailedunderstanding of BG, prerequisite for a discovery • Transinioning to targetedsearches, optimized for specificwell-motivatedmodels (eg: natural SUSY) • Strong push on naturalnessdedicatedsearches for L=2-4.7 fb-1 • Direct sbottom & stop • Gluinomediated stop/sbottom • Direct Gauginos [Also sensitive to directslepton !] • Analyses of 8 TeV data are in progress. Expect 20 fb-1 of data by the end of the year.