Constraining unparticles from top physics at the Tevatron
We study and analyze the recent observations of the top pair production σ(pp̅ →tt̅ ) at the Tevatron through flavor conserving and flavor violating channels via vector and tensor unparticles. The unparticle sector is considered with the possibility of being a color singlet or octet. The modified unparticle propagator is used to investigate the contribution of these unparticles to the observed AFBtt̅ (forward-backward asymmetry in top pair production) and the spin correlation at the Tevatron. We have also studied the impact of the flavor violating couplings of unparticles to the third generation quarks on (a) pair production of same sign tops/antitops σ(pp̅ →tt+t̅ t̅ ) at the Tevatron and (b) the partial top decay width for ΓU(t→uUV). We find that a large region of parameter space is consistent with the measurements of the tt̅ production cross section, AFBtt̅ , and spin correlation coefficient at the Tevatron, and we observe that the top decay width measurement constrains the flavor violating coupling of vector unparticles more severely than the same sign top/antitop production at the Tevatron. We also predict the best point set in the model parameter space for specific choices of dU corresponding to χmin2, evaluated using the mtt̅ spectrum of AFBtt̅ from the data set of Run II of the Tevatron at the integrated luminosity 8.7 fb-1. Our results and analysis are consistent even with unparticle theories that have broken scale invariance, as long as the infrared cutoff scale is much less than the top pair production threshold.