Exclusive dimuon measurements with LHCb

A measurement of exclusive dimuon production provides a clean test of QED and QCD predictions in a low multiplicity environment. Exclusively produced dimuon pairs can be produced by two photon fusion, or through resonances produced by pomeron-photon fusion or double pomeron exchange. We present cross-section measurements for exclusive dimuon production, and the first observations at a proton proton collider of exclusive J/$\psi$, $\psi(2S)$ and $\chi_c$ states, obtained with 37 pb$^{-1}$ of data at a centre-of-mass energy of 7 TeV, collected by the LHCb experiment.