Motivations for a +MET Trigger EGamma and (separately) MET Trigger Meetings 08 Feb 2011 Bruce Schumm, SCIPP/UCSC, For the SUSY Photon + MET Group
Neutralino NLSP Signatures For Bino, branching is 77% , 23% Z. For Wino, branching properties are switched. For Higgsino, no photonic decay, but actual NLSP may be Higgsino/Bino/Wino admixture All can be prompt or metastable (“non-pointing” photons)
p T of Photons (Low Bino Mass) M bino = 200 GeV M gluino=400–700 GeV Et Cut 1 (%)2 (%) Trigger Results for Events Passing Offline Selection Prompt Bino-Like Case (Offline cut analysis) ~85%
Trigger Results for Events Passing Offline Selection g80_loose 40% 2g20_loose41% What about g40_loose MET_40? Note that this trigger should be fully efficient for our current 125 GeV MET requirement, so just look at photon requirement: g40_loose84% Significant improvement. Non-Pointing Bino-Like Case (“GMSB2”)
Prompt Higgsino-Like Admixture Case Explore Something Like 1/ 2[ B + H ] 11 22 g80_loose: 55% g40_loose: 80% 2g20_loose: <3% Sample has exactly one B g and one H Hg Again, MET component of trigger should be fully efficient at MET > 125 GeV Some improvement from adding MET to trigger
Answers to various possible questions: 1)What is expected rate? EF_g40_loose_xe25_noMu 24 Hz EF_g40_loose_xe30_noMu 11 Hz EF_g40_loose_xe35_noMu 4 Hz EF_g40_loose_xe40_noMu 0.4 Hz (From Teresa F. M. ; 15 Jan 2011) 2) How might you measure trigger rate? Thought: use pre-scaled g20_loose. Rate relative to offline requirement of tight photon with E T > 50 GeV should give enough statistics to explore MET turn-on.
3) How general are these studies? The MET scale is set by the neutralino mass, which has a lower limit from the Tevatron of M Bino > 175 GeV. The 125 GeV offline MET cut was conservatively optimized for a 150 GeV Bino MET cut would be higher for (more likely) higher Bino mass While the Tevatron limit can be breached for non-Bino-like neutralinos, the MET > 40 GeV trigger requirement seems quite safe (even considering turn-on extending out to 100 GeV) 4) What is your backup strategy if the rate turn out to be too high? We see from e.g., Higgsino-admixture study that efficiency falls with photon E T requirement. However, MET still has plenty of headroom Increase MET requirement until rate is acceptable
5) What will you use for control samples with this trigger? Control sample for sources with intrinsic MET Nominally, just care about what’s above the 125 GeV cut; would also have significant rate below this to verify samples Control sample for sources with no intrinsic MET These measure instrumental effects; in general can “dial” size of control sample by degree of relaxation of photon selection cuts, at (probably) small cost of systematic control. So prescaled single photon triggers should be fine.
Summary It seems that a photon+MET trigger (for example, EF_g40_loose_xe40_noMu) can provide significant additional sensitivity for model-independent studies with acceptable bandwidth Standard prescaled photon triggers should allow for acceptable control samples and for trigger efficiency studies If rate is too high, can increase MET requirement with little impact on sensitivity