We present a search for a new particle T′ decaying to top quark via T′→t+X, where X is an invisible particle. In a data sample with 4.8fb-1 of integrated luminosity collected by the CDF II detector at Fermilab in pp̄ collisions with √s=1.96TeV, we search for pair production of T′ in the lepton+jets channel, pp̄→tt̄+X+X→ νbqq′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 600GeV/c2, the dark matter particle mass being anywhere below Tm′. The data are consistent with standard model expectations, and we set 95% confidence level limits on the generic production of T ′T̄′→tt̄+X+X. For the dark matter model we exclude T′ at 95% confidence level up to Tm′=360GeV/c2 for mX≤100GeV/c2. © 2011 American Physical Society.
Publication Source (Journal or Book title)
Physical Review Letters
Aaltonen, T., Álvarez González, B., Amerio, S., Amidei, D., Anastassov, A., Annovi, A., Antos, J., Apollinari, G., Appel, J., Apresyan, A., Arisawa, T., Artikov, A., Asaadi, J., Ashmanskas, W., Auerbach, B., Aurisano, A., Azfar, F., Badgett, W., Barbaro-Galtieri, A., Barnes, V., Barnett, B., Barria, P., Bartos, P., Bauce, M., Bauer, G., Bedeschi, F., Beecher, D., & Behari, S. (2011). Search for production of heavy particles decaying to top quarks and invisible particles in pp̄ Collisions at √s=1.96TeV. Physical Review Letters, 106 (19) https://doi.org/10.1103/PhysRevLett.106.191801