# Search for Production of Heavy Particles Decaying to Top Quarks and Invisible Particles in pp̅ Collisions at √s=1.96 TeV

Abstract : We present a search for a new particle $T'$ decaying to top quark via $T^{\prime} \rightarrow t + X$, where $X$ is an invisible particle. In a data sample with 4.8 fb$^{-1}$ of integrated luminosity collected by the CDF II detector at Fermilab in $p\bar{p}$ collisions with $\sqrt{s}=1.96$ TeV, we search for pair production of $T'$ in the lepton+jets channel, $p\bar{p} \rightarrow t\bar{t} +X+X \rightarrow \ell\nu b q q' b + X +X$. We interpret our results primarily in terms of a model where $T'$ are exotic fourth generation quarks and $X$ are dark matter particles. Current direct and indirect bounds on such exotic quarks restrict their masses to be between 300 and 600 GeV$/c^2$, the dark matter particle mass being anywhere below $m_{T^{\prime}}$. The data are consistent with standard model expectations, and we set 95% confidence level limits on the generic production of $T'\bar{T'} \rightarrow t\bar{t}+X+X$. We apply these limits to the dark matter model and exclude the fourth generation exotic quarks $T'$ at 95% confidence level up to $m_{T'}=360$ GeV$/c^{2}$ for $m_X\le 100$ GeV$/c^2$.
Document type :
Journal articles
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http://hal.in2p3.fr/in2p3-00578789
Contributor : Swarna Bassava Connect in order to contact the contributor
Submitted on : Tuesday, March 22, 2011 - 11:54:16 AM
Last modification on : Thursday, November 18, 2021 - 4:06:04 AM

### Citation

T. Aaltonen, B. Alvarez Gonzalezv, S. Amerio, D. Amidei, A. Anastassov, et al.. Search for Production of Heavy Particles Decaying to Top Quarks and Invisible Particles in pp̅ Collisions at √s=1.96 TeV. Physical Review Letters, American Physical Society, 2011, 106, pp.191801. ⟨10.1103/PhysRevLett.106.191801⟩. ⟨in2p3-00578789⟩

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