  We perform a general parton level analysis for the search of heavy resonant
states in the production of top-antitop pairs at the LHC with an integrated
luminosity of 30 fb^-1. We assume the existence of resonances that only couple
to quarks and propose kinematic cuts in order to increase the amount of events
produced through quark-annihilation. We study the interplay between different
variables and their impact on the purity of the selected sample. We make focus
on the longitudinal ($\beta$) and transverse ($p_T$) momentum of the
top-antitop pair, and the scattering angle ($\theta$) in the center of mass
reference frame. We observe that $\beta$ is replaced by $\theta$ as a suitable
discriminating variable of quark-annihilation processes for invariant masses
above 1 TeV. Finally, we illustrate the analysis with a gluon resonance of 1.5
TeV and show the improvement in the sensitivity of the signal when cuts on
$\theta$ are imposed.
