1. τ HLTrigger Optimization Mike B 6 th Nov

2. 2 M. Bachtis - UW The tau High Level Trigger scheme in CMS For the events that pass the L1 Trigger jet reconstruction is applied. Then Calorimeter only cuts are applied to the jets to reduce the rate for the next step This jets are tested for isolation using tracker reconstruction that can be done with pixel or Silicon Tracker

3. 3 M. Bachtis - UW Calorimeter Only cuts What we have: –ECAL Isolation algorithm What we need: –Cut the maximum number of background events before the time consuming track reconstruction in HLT How we are going to do it: –Optimize ECAL Isolation cones/cuts –Add HCAL Isolation cuts too.

4. 4 M. Bachtis - UW SIGNAL: Z tau tau hadronic sample 50 K events in CMSSW 1_6_0 QCD : 7 bins sample 50K events/bin and Cross Sections (pb)‏ –0-15 GeV (5.52E10) –15-20 GeV (1.46E9)‏ –20-30 GeV (6.32E8)‏ –30-50 GeV (1.63E8)‏ –50-80 GeV (2.16E7)‏ –80-120 GeV (3.08E6) –120-170 GeV(4.94E5)‏ MC Samples

5. 5 M. Bachtis - UW MC and acceptance cuts

6. 6 M. Bachtis - UW Matching Cuts

7. 7 M. Bachtis - UW ECAL isolation Uses JetCrystalAssociation Collection to loop through crystals around a Jet Calculates ECAL in a big and small cone (ie 0.4,0.13)‏ This value must be near to 0 because of the narrowness of the tau. The cut is: For studying ECAL cuts we define: Total Et in a cone of R

8. 8 M. Bachtis - UW ECAL Isolation (2)‏ A lot of jets with ECAL Et near zero... Probably jets without an energy correlation in their centers or Hadronic only jets Note that the cone in the default ECAL isolation is centered on the “center of the jet” not on the highest energy crystal...

9. 9 M. Bachtis - UW Defining a Good L2 Tau... A good tau must –be matched to a MC Particle –be matched to an L1 tau(?) -I think not really –be matched to a Particle Flow tau Matching becomes complicated –Introduce a Matching bitmask –u=a+2b+4c a =match to MC bit b =match to l1 bit c =match to PF bit You want these!

10. 10 M. Bachtis - UW Comparing Isolation cones wih QCD This is not done in the optimum way yet I must weigh my events according to the QCD cross sections(next time)‏ Here we actually see a case which is supposed to be worse than what we expect –More High Pt events = More narrower jets

11. 11 M. Bachtis - UW ECAL :Energy in cones QCD Signal

12. 12 M. Bachtis - UW Or in energy fraction to remove Jet Et Convolutions QCD Signal

13. 13 M. Bachtis - UW More HLT Calo Information A lot of info can be extracted by the L2 CaloJetCollections –CaloTower Info, Number of Jets with 60%,90% of energy,Area of jet We look at a similar isolation based on caloTowers We look at seperation based on the other jet properties

14. 14 M. Bachtis - UW HCAL Isolation Cones QCD Signal

15. 15 M. Bachtis - UW And in energy fractions

16. 16 M. Bachtis - UW Jet Parameters QCD Signal

17. 17 M. Bachtis - UW Jet Profile in η,φ space Here we are interested to the jet shape so we calculate an Et weighted covariance Matrix Where Variance in φ is in principle larger than in eta because of the B-Field bending power that spreads the jet a bit.

18. 18 M. Bachtis - UW Jet Covariance Matrix QCD Signal

19. 19 M. Bachtis - UW Proposed efficiency for High level Nominator: Number of MC matched L2 taus that are in events that passed the L1 tau trigger, are matched to a PF object and pass our Calo Cuts Denominator: Number of L2 taus that are in events that passed the L1 Trigger and are matched to a PF object Plots next time for different cut combinations