SUSY with Photons and MET: Introduction and thoughts about

Diphoton and Single Photon AnalysesAnnecyDESY/University of HamburgLiverpool UniversityTokyo TechUniversity of California Santa CruzUniversidad Nacional de La PlataUniversity of WisconsinWeizmann Institute

General Intro

Photon processes in SUSY

mSUGRA

• LSP: lightest neutralino• NLSP: 2nd neutralino• production: 1-loop

GMSB

• LSP: gravitino ( massless)

• NLSP: lightest neutralino• production: tree level

Collider phenomenology depends on nature of LSPs

Signature: + MET (+ X)

This group’s focus so far

What is the X in “(+X)”?This depends on the composition of the NLSP 0:• 0 = Bino B(0 G) ≈ 80% X = 2nd • 0 = [Bino Wino] X = lepton (Jovan)• 0 = [Bino Higgsino] X = b-jet(s) (Ofir)• 0 = [Bino ???] X = as little as possible (CMS: 3 jets with 30 GeV ET.

Other notes:• If Mcolored ≈ M0, additional activity can be very limited

• If G (gravitino) coupling is weak, 0 can be metastable (non-pointing photons!) (Helen)

Diphoton Analysis

Basic Selection: • 2 with PT > 25 GeV• MET > 125 GeV

Limits: Cast in 2D space of Mcolored vs MBino

N.B. Comparison with CMSIn terms of the observed cross section limit, CMS and ATLAS are essentially identical (~25 fb-1), and:

• These can be directly compared (same syst. error content)

• P(e)CMS ≈ 0.1*P(e )ATLAS

• CMS used slightly (~6%) more luminosity

• CMS got slightly lucky (expected 1.5; observed 0)

Despite appearances (mass limit), ATLAS analysis appears superior per fb-1

In addition, ATLAS did not optimize for 1 fb-1 (we used essentially the same analysis as for 0.036 fb-1)

We need to optimize; should result in favorable analysis relative to CMS

Diphoton Analysis: Next StepsFirst things first: we need to explore (clean up?) MET variables for events with high PT photons. From Jason:

Not all of our recovered photons are treated correctly by the MET reconstruction, and we have some anecdotal evidence from our high-MET candidates that this is worse in high-pT photon events. Probably this is because of the straight scaling EM->hadronic JES; this makes the size of the (wrongly applied) correction larger for the high-pT photons.

This will have to be explored at AOD stage and brought forward (officially) into the D3PDs

Diphoton Analysis

Diphoton Analysis

Diphoton Analysis

Diphoton Analysis

SUSY single photon + MET + X

University of California Santa CruzUniversidad Nacional de La Plata

SUSY- Broken in nature

via gravity (mSUGRA)

via gauge mediation (GMSB)

At low energies, most scenarios with similar spectra…

…but possible different phenomenologies at colliders.

(mSUGRA) (GMSB)

Experimental SignatureTrigger:- EF_g40_loose_xe45_medium_noMu/EF_g40_loose_xe55_medium_noMu triggers?- g80_loose g100_loose (5. 1033 ) ?

Selection: - |η| range, Photon pT , Photon quality :Tight?, Etcone (Calo isolation) vs Ptcone (track

isolation)? MET definition, i.e. MET_RefFinal? ( Currently use LocHadTopo) number of Jets?

Efficiencies:- Follow photon efficiency task force!- MET: Bruce please add…..

Background: data driven methods- QCD: Prompt photon (direct / fragmentation) follow SM analysis- W, Z ttbar…