Measured coherent differential cross section of J/$\psi$ photoproduction inultra-peripheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}} } = 2.76$ TeV. The error is the quadratic sum of the statistical and systematic errors. The theoretical calculations described in the text are also shown. The rapidity distributions are shown in a), b) shows the cross section integrated over -3.6 $< y < $ -2.6, and c) shows the ratio of the cross sections in the rapidity intervals -3.1 $< y < $ -2.6 and -3.6 $< y < $ -3.1 The dashed lines in the lower two plots indicate the three model categories discussed in the text. | |