CDF Logo Search for a New Heavy Gauge Boson W' with electron+MET event signature
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We have searched for a new heavy charged vector boson, W', decaying to an electron-neutrino pair in ppbar collisions at a center-of-mass energy of 1.96 TeV, using CDF II data corresponding to the integrated luminosity of 5.3/fb assuming the standard model strength couplings. We found no evidence of this decay channel in the search results looking for an excess in the high mass regions, and thus set limits on the production cross section times branching fraction, assuming the neutrino from a W' boson decay to be light. If we assume the manifest left-right symmetric model, we exclude a W' boson with mass less than 1.1 TeV/c^2 at the 95% confidence level.

Blessed Plots and Tables

Event Selection Cuts :

1. one isolated central electron with Et > 25 GeV
2. MET > 25 GeV
3. backgrounds vetoing : removed dilepton events and required the ratio cut of electron Et to MET with 0.4 < Et/MET < 2.5
Electron Et distributions of Data and total backgrounds. [eps or gif]
MET distributions of Data and total backgrounds [eps or gif]
The ratio distributions of electron Et to MET. [eps or gif]
Event Display for the highest Mt event at 856 GeV/c^2 in the Data. [eps or gif]

Background Estimations :

SM backgrounds are estimated using MC sample that generated with Pythia except multijet background. Multijet background is estimated with angular distribution method from data sample.
Background expectations. [eps or gif]
The azimuthal opening angle distribution between the primary electron candidate and vector summed Et of all other jets. [eps or gif]
Comparison of Data and expected SM backgrounds in transverse mass distribution. [eps or gif]

W' Signal MC :

W' to e nu signal events are generated using Pythia.
The invariant mass shapes of W' to e nu at generation level. [eps or gif]
The transverse mass shapes of W' to e nu at generation level. [eps or gif]
Total acceptance times efficiency for W' to e nu signals. [eps or gif]
W' to e nu signal expectations. [eps or gif]
The expected Mt distributions in 5.3/fb of data for the total backgrounds and the signal of W' to e nu. [eps or gif]

Search Results (binned likelihood fitting in Mt distribution) :

Transverse mass fit in W/W' to e nu candidate event sample of data using only SM backgrounds. [eps or gif]
The search results of the binned likelihood fitting using only backgrounds. Shown are the expected numbers of background events in high Mt region above 200 GeV/c^{2}. [eps or gif]
The search results of the binned likelihood fitting with signal + background. [eps or gif]

Systematic Uncertainties :

Systematic uncertainties come from parton density functions(PDFs), electron energy scale, initial/final state radiation(ISR/FSR), relative fractions of backgrounds expect multijet background, jet energy scale, and multijet background.
Total systematic uncertainties as a function of W' mass. [eps or gif]

95% C.L. limits :

The 95 % CL limits on the signal contribution(beta_95), cross section times branching fraction of W' to e nu process assuming the SM strength couplings and their 95% C.L. limits. [eps or gif]
95 % C.L. limits on the cross section times branching fraction. [eps or gif]
95% C.L. limits on the cross section times branching fraction and the expected limits on the background-only pseudoexperiments. [eps or gif]

This Page was last updated Sep. 14th, 2010 by Yuchul Yang.
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