We perform a general parton level analysis for the search of heavy resonant states in the production of t ¯ t 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 number of events produced through quark annihilation. We study the interplay between different variables and their impact on the purity of the selected sample. We focus on the longitudinal (β) and transverse (pT) momenta of the t ¯ t pair and the scattering angle (θ) in the center of mass reference frame. We observe that β is replaced by θ 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 θ are imposed.Instituto de Física La Plata