Measurement of exclusive Upsilon photoproduction in pPb collisions with the CMS experiment

The aim of this study is to measure exclusive photoproduction of three resonant particles, $\bf \Upsilon(1S)$, $\bf \Upsilon(2S)$ and $\bf \Upsilon(3S)$ mesons,in their $\mu^{+}\mu^{-}$ decay modes, in ultraperipheral pPb collisions.The $\bf \Upsilon(1S)$ photoproduction cross section are measured, over the rapidity range $\vert y \vert < 2.2$, as a function of the photon-proton center-of-mass energy, $W_{\gamma p}$, which provides valuable information of the gluon distribution at small values of parton fractional momenta $x$. The slope of the squared transverse momentum ($p_{T}^2$) dependent differential cross section is measured to determine the size of the production region. The results are compared to other measurements and to theoretical predictions.