Diphoton+X 2015: Overview of Plans and Goals Bruce Schumm SCIPP On Behalf of the Photon+X Working Group La Plata, LPNHE Paris, Milano, Tokyo Tech, UCSC 03 June 2015

8 Tev Results Draft includes Diphoton Photon+b Photon+jets Photon+l Exercise of mushing all four results together in a single paper was taxing but worthwhile  Can we work more closely together to make the combined paper easier and more natural to write? June 03 2015

Photon + X Group Organization New Photon+X Twiki (thanks to Hernan) https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/SUSYPhotonX Meetings (plan on 90 min) Mondays 16:30 CERN time Chaired on rotating basis by Photon+X contact people Leonardo Carminati (Milano) Bruce Schumm (UCSC) Hernan Wahlberg (La Plata) June 03 2015

Photon + X Group Commonality TASKS POTENTIALLY COMMON TO ALL GROUPS SM MC samples xAOD framework issues Code snippets reflecting agreed upon object definitions Isolation variable code Pseudophoton object definition code e->gamma fake rate study dPhi studies (one-sided or two-sided?) Common systematics tasks? Common journal submission June 03 2015

8 TeV Gluino-bino model limits 8 TeV Wino-bino model limits Diphoton Analysis 8 TeV Gluino-bino model limits 8 TeV Wino-bino model limits June 03 2015

Tasks Overview KEY: DONE UNDERWAY UPCOMING Code/Infrastructure xAOD Derivations Higher-level infrastructure (Ryan’s package) Events variables (MET with photons, etc.) Event selection Preliminary studies Optimization Backgrounds QCD Electroweak Irreducible Models SM samples Strong & EW signal Full vs. fast sim (More on this in a moment) May 18 2015

Focus Points for Diphoton Analysis As before, optimize separately for low/high bino mass for both strong (gluino) and EW (wino) production Assume same a*e (about 12%) and expected #events limits (3 events for strong and 5 events for weak production) Assume 1.5 fb-1 luminosity at 13 TeV Mass of focus point is that giving cross section of 3 events = (1.5 fb-1) * (gluino) * (0.12)  gluino = 17 fb 5 events = (1.5 fb-1) * (wino) * (0.12)  wino = 28 fb  Mgluino = 1500 GeV Mwino = 600 GeV June 03 2015

Diphoton Analysis Issues Not planning to use SUSY derivations (using EXOT10) Next big step to get underway is optimization; for this we await completion of the MC samples Only need four signal focus points (40,000 events)  Can we get highest priority for these points? Also need , -jet, W, Z, tt, W and Z samples in order to perform optimization June 03 2015

Starting to work on backup note June 03 2015

Thoughts About Diphoton Analysis Timeline Optimization should take ~2 weeks once MC samples are available (July 1?) Background estimate techniques in place on roughly the same time scale Except for QCD background, approaches largely identical to those of the 8 TeV analysis, but almost all rely on controls making use of 13 TeV data Will develop control samples with limited initial data but will need to run through full data set and assemble estimated when the full sample becomes available. June 03 2015

Models SM samples defined; generation underway. Much overlap with other groups; much hard work by Milano group! Gluino, wino grids defined All BF and decay length issues resolved Fast Sim sufficiently validated Of order ~2m events at 10K/point, more or less approved Final validation step (generator-level filter to ensure two binos in each event) underway Need this soon! (optimization) May 18 2015

Gluino-Bino Grid (not quite final version) May 18 2015

Wino-Bino Grid (also not quite final) May 18 2015

Backgrounds - QCD Prior approach was to assume real diphotons are 7525% of low-MET background Diphoton MC used to estimate high-MET contribution Pseudophoton control sample scaled to remainder of low-MET events used to estimate -jet contribution Using 8 TeV data to explore new approach (ABCD method with pseudophotons and relaxed isolation); preliminary results expected soon If this doesn’t work, will need to fall back to old pseudophoton control-sample technique May 18 2015

Backgrounds - EW Estimate with e control sample scaled by e fake rate Need to select e control sample Tag&probe study of e fake rate underway [Giacomo] MAYBE: W MC suggests that ~25% of EW background doesn’t arise from e fakes Some of this may be accounted for in QCD background Some of QCD background may include e fake events Prior approach was to include 25% systematic error on the EW background Perform QCD/EW background overlap study? May 18 2015

Backgrounds - Irreducible W contribution estimated via l control sample and simultaneous fit with SR Question about comparison w/ VBFNLO expectation Need to develop control sample and explore Z contribution from Sherpa, scaled to VBFNLO (via MadGraph) in relevant kinematic region Big difference between VBFNLO and Sherpa not understood (Sherpa much larger) Need to revisit May 18 2015

Event Selection: Preliminary Studies In past, formal optimization was last step, considering only M_eff (or HT) , MET Individual, preliminary studies used to establish Photon PT cut; see e.g. https://indico.cern.ch/event/165989/contribution/0/material/slides/0.pdf Δφ-MET : make use of or not; cut value. Should we also cut on (Δφ-MET - )? Δφjet-MET : cut value. Should we also cut on (Δφjet-MET - )? For 8 TeV, used Meff vs. MET visualization plane (see below) Will need signal grid points for this already! May 18 2015

Optimization: The Conundrum How to estimate backgrounds when final background estimates not available? For 8 TeV analysis optimization, backgrounds estimated by QCD background estimated by scaling 1 tight + 1 non-isolated pseudophoton sample to 2 tight pseudophoton sample with no Meff (HT) cut for 0 < 60 < MET (DATA) EW background estimated by scaling e sample by uniform 2% e scale factor (DATA) W, Z from MC SUSY group will accept leaving final data-driven step and quick reoptimization before unblinding. Or, pre-optimize as a function of one to-be-determined background value May 18 2015

TASKS POTENTIALLY COMMON TO ALL GROUPS SM MC samples xAOD framework issues (not completely sure what I mean by this…) Code snippets reflecting agreed-upon object definitions Isolation variable code Pseudophoton object definition code e->gamma fake rate study dPhi studies (one-sided or two-sided?) MAYBE? Common derivation (probably not since different triggers)? Common systematics tasks? May 18 2015

Code/Infrastructure xAOD-based analysis: TokyoTech, UCSC need to catch up Derivations followed through upon by Milano (status?) Higher-level statistics and plotting utility (Ryan…) Past quantities that have required study (do we need to look into these?) MET Isolation definition ??? March 29 2015

Optimization: 8 TeV Approach Last step done by inspection of Meff (or HT) vs MET plane Can be confounded by statistics; also look at background and signal stats over same plane See 8 TeV backup note WP2 Optimization NO YES March 29 2015

What SRs to Create? For 8 TeV Analysis Strong production: High Meff; backgrounds near 0 EW production: Intermediate HT; backgrounds 1-2 events Low mass bino, high mass bino for both SP1, SP2, WP1, WP2 Also: Model-independent SR (MIS), no Meff (HT) cut. Based on choosing MET cut at which EW and QCD backgrounds about the same (~1 event each) March 29 2015

Model-Independent SR (?) 8 TeV analysis: at MET=250, Meff = 0 backgrounds about same EW QCD Question: Should we rethink? What do we really want to do to minimize chance that we miss a signal? Hmmm…. How do we think about this? March 29 2015

What Physics Could Hide Signal with Dominant BF into Photons and DM? Degenerate SUSY scenarios? No – energy has to go somewhere. We would see it in photons and/or MET. Photons will not be soft because decaying state will either be high-mass or boosted. Low photonic BF? Would need to accelerate single-photon analyses. Not really practical. Long-lived scenarios? Need to re-create non-pointing photon reconstruction. Probably no competition from CMS here anyway. Perhaps most likely scenario is lower-than-expected cross section from non-SUSY process. Probably best addressed by what was done before, or perhaps just use no Meff or Ht cut and use lower MET cut of the other, model-dependent SRs. Could perhaps also maintain low photon ET cut but that could be a “can of worms”. March 29 2015

Wrap UP I haven’t mentioned limit setting within HistFitter Immediate motivation is to get to unblind before or simultaneous with CMS I’m not assuming we’ll necessary be setting limits! Our work is cut out for us. Thoughts? We should start writing the skeleton of the backup note. If anyone is itching to do this, by all means. Otherwise, I’m very happy to do that. March 29 2015