by Giulia Manca
LHCb is one of the four LHC experiments which started collecting pp collisions data in 2010 at a centre-of-mass energy of 7 TeV. With its forward geometry, LHCb is dedicated to the study of heavy-flavor production and decay. The solid understanding of the muon triggers and identification is a crucial milestone towards the sophisticated analyses searching for new physics or CP violation in B decays. We present the study of the production of quarkonia resonances in the dimuon sample collected in the first year of data taking, corresponding to up to 35 pb-1. The promptly-produced J/psi and psi(2S) are separated from the b-hadron decay products using topological information. We will discuss the measurements of the double differential production cross-section of J/psi, Psi(2S) and Upsilon states, as well as their impact on the understanding of quarkonia production. The results will be shown in the framework of different theory models and compared with other experiments.