First polarisation measurement of coherently photoproduced J/ <italic>&#968;</italic> in ultra-peripheral Pb&#8211;Pb collisions at sNN=5.02 TeV

The first measurement of the polarisation of coherently photoproduced J/ψ mesons in ultra-peripheral Pb–Pb collisions, using data at sNN=5.02 TeV, is presented. The J/ψ meson is measured via its dimuon decay channel in the forward rapidity interval −4.0s-channel helicity conservation hypothesis.