Search for production of top quark pairs plus invisible particles at CDF

K. Rao1, D. Whiteson1

1 University of California, Irvine



for the CDF Collaboration

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Abstract


We present a search for dark matter through the production of exotic $4^{th}$ generation quarks $t^{\prime}$ decaying via $t^{\prime} \rightarrow t + X$, where X is dark matter.We search the lepton+jets channel in data from the CDF experiment at the Tevatron collider, and require at least 4 jets and large missing transverse energy (100-160 GeV). In the lepton + jets channel the final state looks like $l + \nu + qq^{\prime}+bb^{\prime}+\slashed{E}_{T}$. Current direct and indirect bounds on such exotic quarks restrict their masses to be between 300 and 600 GeV, and the dark matter's mass anywhere below $m_{T^{\prime}}$. We find that using 4.8 $fb^{-1}$ of data will allow for exclusion of


$m_{T^{\prime}}<360GeV$ at 95% CL for $m_{X}<100GeV$

Primary Result Plots/Tables

95% CL exclusion in mass parameter space .png
Theory NLO vs observed cross-section upper limit for LSP mass = 1GeV.png
Theory NLO vs observed cross-section upper limit for LSP mass = 20GeV.png
95% CL cross-section upper limits in mass parameter space (300GeV<=m_{T'}<=370GeV).png
95% CL cross-section upper limits in mass parameter space (200GeV<=m_{T'}<=280GeV).png
95% CL cross-section upper limits in mass parameter space.png
For each mass point tested we list the MET cut used the expected limit(BUL) vs observed limit.png

Supporting Results Plots and Tables

Background vs data in Njets.
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Background vs data in missing energy with two different selections.
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Background vs data in lepton transverse energy in three control regions. png
Background vs data in MTW(transverse mass of leptonically decaying W candidate) in three control regions. png
Background vs Signals(three different mass points) in mTW in the analysis region.
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Number of events for signals, backgrounds and data with systematic errors with three different selections.png
Expected exclusion with +/- 1sigma vs observed exclusion. png