Physics with Photons and Missing Energy at ATLAS DOE Site Visit Thursday June 14, 2012 Damiani *, Kim, Kuhl, Litke, Mitrevski, Nielsen, Schumm (convener) Collaborators: Annecy, DESY, La Plata, Liverpool, Penn, Tokyo Tech, Wiezmann * Ph.D. June 2012

SCIPP Roles Played Diphoton + MET (flagship photon + MET analysis)  Schumm convener, cast of ~ dozen  Damiani thesis Photon + Bjets + MET  Nielsen, Kuhl, with Weizmann Photon + Lepton + MET  Mitrevski Overall Photon(s) + X + MET  Schumm is contact person

Papers Search for Diphoton Events with Large Missing Transverse Momentum in 1 fb -1 of 7 TeV Proton-Proton Collision Data with the ATLAS Detector Phys. Lett. B710 (2012) Search for Diphoton Events with Large Missing Transverse Momentum in 36 pb-1 of 7 TeV Proton-Proton Collision Data with the ATLAS Detector Eur. Phys. J. C71 (2011) 1744

Full 2011 diphoton + MET result (5 fb -1 ) in Collaboration- Wide Review for ICHEP and then Phys. Lett. B

ATLAS Recognition Invited Talks  Mitrevski: Photons+MET, SUSY11, Aug 2011  Schumm: ATLAS, CIPANP, May 2012 US Talks  Schumm: ATLAS, SUSY Recast (Davis), April 2011  Mitrevski: Photons+MET, BNL SUSY Workshop, May 2011

Photon(s) + MET: Motivation ATLAS searches defined by signature, motivated by one or more BSM physics scenario. Photon(s) + MET Motivations: Gauge-Mediated SUSY Breaking (GMSB)  New “hidden” gauge/messenger sector protects flavor symmetry  Photons from gaugino  gravitino decay Universal Extra Dimensions (UED)  Weak gravity excused by leaking into extra dimensions  Gravity-mediated KK photon decay  KK   + G (KK)

Hidden gauge sector breaks SUSY via weakly- coupled messenger interactions LSP is light (<< 1 GeV) gravitino NLSP is typically neutralino  0 1 Bino-like neutralino is natural, which decays with ~75% BF to photon-gravitino  2 photons + missing transverse energy (MET)  0 1 could also be admixture of Wino, Higgsino  Photon + (lepton, bjets) + MET GMSB Phenomonology

5 fb -1 Diphoton+MET Strategy Tighter photon selection suppresses backgrounds Three analysis regions targeting A: High-mass (strong) production, heavy  0 1 B: High-mass production, light  0 1 C: Low-mass (electroweak) production Analysis Cuts Expected Background Observed Signal

5 fb -1 Diphoton+MET Results Tighter photon selection (no pixel hits for conversions) Optimized signal regions & highter photon E T thresh  ~100 GeV greater reach than CMS (like x3 stats):

New Analysis I:  + bjets + MET

 + bjet + MET Motivation and Search Shih, Ruderman One photon, E T > 125 GeV MET > 150 GeV 2 E T > 50 jets, one b-tagged  min > 0.4 M T ( ,MET) > 100 GeV Lepton veto

 + bjet + MET: Prospects For  0 1 ~50/50 h/B mix, can approach m g ~ 700 GeV when m  > ~200 GeV Target: SUSY2012 Beijing, Aug First analysis of cascade involving photon + bjet

New Analysis II: Photon + Lepton + MET “Lead” is Jovan Mitrevski Target EW production, and bino/wino admixture for  0 1 ) Start with l =  to avoid jet (QCD) backgrounds Backgrounds (order of size): W , tt(+  ), W+jets, Z + ( ,jets)  Only existing result is CMS, 35 pb -1 EW Production Shih, Ruderman Wino-like NLSP

 + Lepton + MET Prospects SR QCD XR1 XR2 TCR Background approach nearing completion Systematics ~ next week Histogram-fit limits ~ 2weeks Hope to make SUSY12 WCR WW

SCIPP playing leading role in multi-signature arena Attentive analysis yields very aggressive limits 2011 (5 fb -1 ) Two papers published, one in CWR, two more in analysis stage 2012 (20 fb 8 TeV) Expect 10-15% improvement from each of higher energy, statistics  25% increase in reach (?) Beyond 14 TeV will open up a whole new window Photon(s) + MET Summary

BACKUP

The “minimal” SPS8 model is ad hoc, selected somewhat arbitrarily as a concrete model for which different facilities could be compared In particular, no reason why EW and colored partner scales need be coupled  Generalize model so that one strong partner, one EW partner are light, all other partner masses are high (~1.5 TeV) Free parameters are gluino, Bino-like  1 0 masses: General Gauge Mediation (GGM)

Two major sources: MET Distribution from QCD Sources Loose photon control sample Z  e + e - to model  events MET from EW Sources (Ws, ttbar) e  control sample from data, MC Scale to  contribution with e   fake rate from Z  ee studies Data-Driven Background Estimate

Nothing there with 36 pb -1, so we set limits… ISO: New Physics! Signal region

ATLAS has better photon reconstruction than CMS (conversions) Observed, Expected Limits

7/25/11: Accepted (pending small revisions)

Observed in Signal Region vs. Expected Background

20101 (~1 fb -1 ) Analysis x increase in data sample size  12x improvement in cross-section limit But:   1/M 9 for M gluino ~ 900 GeV!