1 / 13

Status Update: Search for Low Mass Strings at CMS

Status Update: Search for Low Mass Strings at CMS. Andy Yen. Intro. Superstrings can lead to the following non-SM process: gg→gγ Extra contribution to the SM gamma+jet . Ms ~ 1 TeV , 100 evt for 200pb-1. 2. Data Samples.

penda
Download Presentation

Status Update: Search for Low Mass Strings at CMS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Status Update: Search for Low Mass Strings at CMS Andy Yen

  2. Intro • Superstrings can lead to the following non-SM process: gg→gγ • Extra contribution to the SM gamma+jet. • Ms ~ 1 TeV, 100 evt for 200pb-1 2

  3. Data Samples • Strings Signal: 10k events, Ms=1 TeV, ckin(3)>200 GeV, correct kinematics, incorrect matrix element weights. CMSSW 3.2.x • Photon+Jet/QCD Dijet (CMSSW 2.2.x) • Ckin(3)>170, 1M/1.5M [19400pb-1, 24pb-1] • Chin(3)>300, 300k/1M [71548, 273] • Ckin(3)>470, 100k/3M [221484, 9500] • Ckin(3)>800, 100k/3M [5000000,250000] • Ckin(3)>1400, 100k/.5M

  4. Photon Reconstruction • Require dR within 0.15 of MC. • 32x eff (string signal): 95.465 [right] • 22x eff (pt>470 GeVpho+jet): 96.406 [left]

  5. Jet Reconstruction • Jets Objects used • iterativeCone5CaloJet • sisCone5PFJet • iterativeCone algorithm • Colinear unsafe • Infrared unsafe • sisCone algorithm • “seedless infrared safe cone” • Particle Flow • Reconstruct ALL particles in event • Uses all CMS subdetectors

  6. Jet Response (continued) • iterativeCone5CaloJets • CMSSW 2.2.x vs 3.2.1 • Arbitrary normalization Mean: 0.79 Sigma: .106 Mean: 0.77 Sigma: .123 6

  7. Jet Energy Response • CMSSW 3.2.1 • IterativeCone5CaloJets vs sisCone5PFJets • Crystal Ball Fit with 2 polynomial tails Mean: 0.77 Sigma: .123 Mean: 0.94 Sigma: .082 7

  8. Collinear Safety? • Even in the PF Jet, there is still a tail at low values. • Approximately 10% of reconstructed Jets have 2nd Jet within dR<1 [for sisCone PF jets]

  9. Collinear correction • Take the vector sum of the momentum of the two jets • Use Pt-weighted average of eta and phi (account for phi discontinuity). • Improvements in eta/phi and energy response!

  10. Response Improvements Mean: 0.95 Sigma: .0596

  11. Jet Reco Efficiency

  12. Event Selection • Describe the selection here + cut efficiencies for signal and backgrounds

More Related