Exploring new possibilities to discover a light pseudo-scalar at LHCb

We study the possibility of observing a light pseudo-scalar $a$ at LHCb. We target the mass region $1\lesssim m_a\lesssim 60$ GeV and various decay channels, some of which have never been considered before: muon pairs, tau pairs, $D$ meson pairs, and di-photon. We interpret the results in the context of models of 4D Composite Higgs and Partial Compositeness in particular.