1 / 6

High Mass Drell Yan Differential Cross-section (ATLAS)

High Mass Drell Yan Differential Cross-section (ATLAS). Paul Bell University of Geneva on behalf of the high mass DY analysis team 18 / 2 / 2013. The measurement. Measurement of DY differential cross section in di -electron channel As function of di -electron invariant mass

Download Presentation

High Mass Drell Yan Differential Cross-section (ATLAS)

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. High Mass Drell Yan Differential Cross-section (ATLAS) Paul Bell University of Geneva on behalf of the high mass DY analysis team 18/2/2013

  2. The measurement • Measurement of DY differential cross section in di-electron channel • As function of di-electron invariant mass • In “high mass” region = 116 – 1500 GeV • Within “extended fiducial” region of electron pT > 25 GeV and | eta | < 2.5 • CONF note: • https://cds.cern.ch/record/1493623 • (paper in approval) • Main backgrounds: • W + jets & multijets where • jet fakes the electron ID • => data driven, 4 methods • Other backgrounds from MC

  3. “Unfolding” method • Fiducial cross section within extended fiducialregion given by • where CDYis the correction factor, given by where NMC,reco = sum of MC signal events after simulation and selection in measured fiducial region (excludes the “crack” region) NMC,gen-fid = sum of MC signal events at generator levelwithin extendedfiducial region i.e. CDY includes the small extrapolation over the crack region. Cross-section measured at different levels of QED FSR correction corresponding to different truth level definitions of NMC,gen-fid: • Born level: Using electrons before QED FSR, i.e. full QED correction • dressed level: Where 4-vectors of the bare lepton and allQED FSR photons within a cone of ∆R < 0.1 are resummed to perform a partial QED FSR correction

  4. Results and systematics • Statistical uncertainty dominates for • mee > 500 GeV • Reaches 50% in highest mee bin • Total systematic uncertainty within 10% • Dominated at low meeby electron efficiency and at high meeby background estimate

  5. Results: generator comparison • MC comparison at dressed level • MC predictions agree well in shape only, after scaling globally

  6. Results: FEWZ 3.1 comparison • FEWZ 3.1 comparison • at Born level with • recent NNLO PDFs • FEWZ allows (N)NLO • QCD corrections to be combined with the NLO electroweak corrections • Choice of EW scheme, Gµor α(MZ), at most 0.4% effect, after applying NLO electroweak corrections • Contribution fromphoton-induced (PI) background, evaluated at LO using MRST2004qed • Correction fromreal W/Z radiation evaluated using MADGRAPH 5, at most 2% at highest mee (not shown)

More Related