slide1 n.
Download
Skip this Video
Download Presentation
Studies of W’  tb  Wbb  lvbb

Loading in 2 Seconds...

play fullscreen
1 / 11

Studies of W’  tb  Wbb  lvbb - PowerPoint PPT Presentation


  • 59 Views
  • Uploaded on

Studies of W’  tb  Wbb  lvbb. Why W' important?. Many beyond-the-standard model theories have predicted W' Extra-dimension model Theories that have an extra SU(2) gauge group Right-handed W boson Technicolor theory Little higgs theory Main decay channels: W' -> e/mu + neutrino

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Studies of W’  tb  Wbb  lvbb' - carsyn


Download Now 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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide2

Why W' important?

  • Many beyond-the-standard model theories have predicted W'
    • Extra-dimension model
    • Theories that have an extra SU(2) gauge group
    • Right-handed W boson
    • Technicolor theory
    • Little higgs theory
  • Main decay channels:
    • W' -> e/mu + neutrino
    • W' -> tb
slide3

Current limits of W'

  • Standard model couplings assumed
  • W' -> lnu
    • CDF: 1.12TeV
    • ATLAS: 1.49TeV (a soon-published result pushes the limit to 2.15TeV)
    • CMS: 1.58TeV
  • W' -> tb
    • CDF (right-handed coupling)
      • mass(W') > mass(right-handed neutrino): 800GeV
      • mass(W') < mass(right-handed neutrino): 825GeV
    • D0
      • mass(W') > mass(right-handed neutrino)
        • left-handed coupling: 863GeV
        • right-handed coupling: 885GeV
        • both couplings: 916GeV
      • mass(W') < mass(right-handed neutrino)
        • right-handed coupling: 890GeV
    • LHC experiments: no results yet
slide4

Why W' -> tb important?

  • Mass limit of W'->lnu greater than 1.5TeV, but standard model coupling is assumed
  • In reality, W' may weakly coupled to leptonic channel
  • There are models that W' is leptophobic
  • It is possible that we find something in hadronic channel for W' < 1.5TeV
  • W'->tb channel provides information about the chirality of W' but not the leptonic channel
  • Question:
  • Given that the current limit of W'->tb is at least 800GeV
  • Should we optimize cuts for W' mass ~800GeV?
slide6

Introduction to matrix method

  • Measuring QCD with the help of two control regions
  • Region 1 gives the probability of loose real muons being tight real muons
  • Region 2 gives the probability of loose fake muons being tight loose muons
  • N(loose) = N(loose,real) + N(loose, fake)
  • N(tight) = N(tight,real) + N(tight, fake)
  • N(tight) = r*N(loose,real) + f*N(loose, fake)
  • Where:
    • N(loose): number of events that have a loose muon, selected MET, at least two jets, and a b-tag
    • N(loose,real/fake): number of events that have a loose real/fake muon, selected MET, at least two jets, and a b-tag
    • N(tight): number of events that have a tight muon, selected MET, at least two jets, and a b-tag
    • N(tight,real/fake): number of events that have a tight real/fake muon, selected MET, at least two jets, and a b-tag
    • r: efficiency of loose real muons being tight = N(tight,real)/N(loose,real)
    • f: efficiency of loose fake muons being tight = N(tight,fake)/N(tight,fake)
slide7

Introduction to matrix method

  • Loose muons: pass through all cuts except isolation cut
  • Tight muons: pass through all cuts (including isolation cut)
  • Region 1:
  • Tag-and-probe events:
    • 80GeV < mass of Zmumu < 100GeV
    • muons with opposite charges
    • Tag muon is tight, probe muon satisfies the loose requirement
  • Probe muons give N(loose,real) and N(tight,real)
  • Give r (with assumptions)
  • Region 2:
  • QCD region:
    • transverse mass of W < 20 GeV
    • transverse mass of W + MET < 60 GeV
  • Give N(loose,fake) and N(tight,fake)
  • Give f (with assumptions)
slide8

N(loose) = N(loose,real) + N(loose, fake)

N(tight) = r*N(loose,real) + f*N(loose, fake)

full selection (b-tag included)

QCD shape obtained from matrix method

QCD scale factor found by template fit

slide9

Cross-check that “real muon region” really gives real muons

Z->mumu mass distributionexactly two same charge muons

no constraint on number of jets

Z->mumu mass distributionexactly two opposite charge muons

no constraint on number of jets

slide10

80GeV < Zmass < 100GeVexactly two opposite charge muons

number of jets = 0

80GeV < Zmass < 100GeVexactly two opposite charge muons

no constraint on number of jets

efficiency of probe muon passing through isolation cut

80GeV < Zmass < 100GeVexactly two opposite charge muons

at least 2 jets

80GeV < Zmass < 100GeVexactly two opposite charge muons

number of jets = 1