Speaker
Description
The nuclear modification factors $R_{AA}$ and $R_{pA}$ of $\Upsilon$ mesons, measured from PbPb, pPb, and pp collisions at $\sqrt{s_{NN}} = 5.02$ TeV at CMS, are reported. The second-order Fourier coefficients ($v_2$) characterizing the elliptic flow of $\Upsilon$'s in PbPb are also reported. In all cases, the $\Upsilon$'s are reconstructed through their dimuon decay channel, as measured at CMS in the rapidity range $|y|<2.4$. In the presence of a quark-gluon plasma, bottomonia are expected to be suppressed, and their resulting elliptic flow signature should be very small. The $\Upsilon$ production is observed to be suppressed in pPb collisions, and substantially more suppressed in PbPb collisions. Models which incorporate sequential suppression of bottomonia are in better agreement with the data than those which only assume initial-state modification. The $v_2$ of the $\Upsilon$'s in PbPb is found to be consistent with zero.
