The search for missing energy events at the LHC and implications for dark matter search (ATLAS and CMS)

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1 The search for missing energy events at the LHC and implications for dark matter search (ATLAS and CMS) Valery P. Andreev UCLA representing the CMS collaboration th UCLA Symposium on Sources and Detection of Dark Matter and Dark Energy in the Universe February 23, 2012 Marina del Rey, California

2 Outline Lightest Supersymmetric Particle (LSP)! is a possible candidate for the Cold Dark Matter " Introduction LHC, ATLAS and CMS detectors SUSY searches at LHC ATLAS and CMS results implications Conclusions Dark Matter 2012 Valery Andreev (UCLA) 2

3 Supersymmetry (SUSY) to solve the hierarchy problem (EWK scale GUT scale) a framework for the unification of particle and gravity a broken symmetry provided R-parity conservation pair production dark matter candidate (LSP = stable, neutral, weakly interacting) Dark Matter 2012 Valery Andreev (UCLA) 3

4 Typical SUSY decay chains Typical event topology missing energy multiple hadronic (b) jets number of leptons Dark Matter 2012 Valery Andreev (UCLA) 4

5 LHC event rates SUSY at - inelastic cross section Dark Matter 2012 Valery Andreev (UCLA) 5

6 Large Hadron Collider (LHC)! CMS ATLAS CMS 7 TeV Run Status, 2011 Maximum luminosity = cm-2s-1 Recorded luminosity = 5.2 fb-1 cm-2s-1 cm-2s-1 ATLAS 7 TeV Run Status, 2011 Maximum luminosity = cm-2s-1 Recorded luminosity = 5.25 fb-1 Dark Matter 2012 Valery Andreev (UCLA) 6

7 The CMS detector Onion structure: Tracker Calorimeters Muon system Precise e, µ, γ, jets, E T Efficient b tagging, τ detection Dark Matter 2012 Valery Andreev (UCLA) 7

8 The ATLAS detector! Tile CAL LAr CAL for precise and efficient measurements Length: 46 m Diameter: 22 m Weight: 7,000 t Toroids 2T solenoid TRT and Si tracker Muon detector Dark Matter 2012 Valery Andreev (UCLA) 8

9 ATLAS & CMS: first, rediscover the Standard Model important for reliable background estimate in New Physics searches Dark Matter 2012 Valery Andreev (UCLA) 9

10 SUSY search: analysis technology define signal region (SR) to maximize sensitivity discriminating variables ( T, m eff, razor, ) background estimate data-driven (control regions (CR), data vs MC) SR transfer factor, from data or MC CR no excess of data over SM expectation, so far set a limit (model-independent or simplified model, CMSSM, MSUGRA, GMSB, ), while each time hoping for an excess E miss Dark Matter 2012 Valery Andreev (UCLA)

11 Missing transverse energy an example: search in all-hadronic events with missing energy Events / 0 GeV CMS Preliminary, L = 1.1 fb, Data s = 7 TeV Bkg. expectation from MC W(l!)+Jets Z(!!)+Jets tt+jets QCD Susy LM4 Events / 20 GeV CMS Preliminary, L = 1.1 fb, Data s = 7 TeV Bkg. expectation from MC W(l!)+Jets Z(!!)+Jets tt+jets QCD Susy LM4 crucial variable in searches with R-parity conservation 1 1 CMS: PAS-SUS CMS Preliminary, L = 1.1 fb, H T s = 7 TeV (GeV) H T (GeV) Events / 0 GeV 3 2 Data Bkg. expectation from MC W(l!)+Jets Z(!!)+Jets tt+jets QCD Susy LM4 ATLAS: arxiv: M eff ( = H +H T ) (GeV) T Dark Matter 2012 Valery Andreev (UCLA) 11

12 CMS: some SUSY searches results in CMSSM (m 0,m 1/2 ) plane m 0 and m 1/2 are universal scalar and gaugino masses, respectively 20 vs 2011 exclusion contours, the area below the curves is excluded Dark Matter 2012 Valery Andreev (UCLA) 12

13 Search for SUZY in Z+jets+MET events CMS: full 2011 data sample analyzed, 4.7 pb -1 ; two approaches 1) MET 2) JetZBalance MET JZB Simplified model Dark Matter 2012 Valery Andreev (UCLA) 13

14 Search for Stop and Sbottom at LHC ATLAS: direct and gluino mediated production considered, 2 pb -1 source: X. Poveda, LHC Physics seminar, 14 Feb 2012; ATLAS-CONF ,3,4,5; arxiv: Dark Matter 2012 Valery Andreev (UCLA) 14

15 ATLAS SUSY searches status (exclusion limits) Dark Matter 2012 Valery Andreev (UCLA) 15

16 CMS: SUSY searches results excluded mass scale in Simplified Model spectra q P 2 P 1 g g q q q χ 0 χ 0 q P 2 P 1 q q χ 0 χ 0 q Dark Matter 2012 Valery Andreev (UCLA) 16

17 ATLAS searches status (II) (exclusion limits) Dark Matter 2012 Valery Andreev (UCLA) 17

18 Compatibility between laboratory searches and WMAP results J.Ellis,K.A.Olive,Y.Santoso,V.C.Spanos, hep-ph/ favored by g 2 (µ + ) µ at 2-σ level tanβ 55 5 Dark Matter 2012 Valery Andreev (UCLA) 18

19 Compatibility between laboratory searches and WMAP results J.Ellis,K.A.Olive,Y.Santoso,V.C.Spanos, hep-ph/ favored by g 2 (µ + ) µ tanβ 55 5 Dark Matter 2012 Valery Andreev (UCLA) 19

20 LHC: ATLAS & CMS results implication for Dark Matter search P.J.Fox, R. Harnik, J. Kopp, Y. Tsai arxiv: v1, 20 Sep 2011 Dark matter production in association with mono-jet Dark Matter 2012 Valery Andreev (UCLA) 20

21 LHC: ATLAS & CMS results implication for Dark Matter search P.J.Fox, R. Harnik, J. Kopp, Y. Tsai arxiv: v1, 20 Sep 2011 Dark matter production in association with mono-photon Dark Matter 2012 Valery Andreev (UCLA) 21

22 SUSY spectroscopy Gluino, sbottom and squark reconstruction reconstruction starts with χ 2 0 l + l - χ 1 0 assuming Dark Matter 2012 Valery Andreev (UCLA) 22

23 Conclusions Dark Matter provides an indication of a New Physics SUSY LSP is a candidate for Dark Matter No signs of SUSY at LHC so far a plenty of new (full statistics) measurements will be released at Moriond Stay tuned! 2012 LHC will run with increased energy of 8 TeV to deliver 15 fb -1 per experiment (ATLAS, CMS) If there is a ~ TeV-scale SUSY dark matter particle LHC will discover SUSY and allow detailed studies and parameters determination Dark Matter 2012 Valery Andreev (UCLA) 23