Measurement of $W\rightarrow\mu\nu$ production in $p$+Pb collision at $\sqrt{s_{_\text{NN}}}=5.02$ TeV with ATLAS detector at the LHC

The ATLAS collaboration has measured $W\rightarrow\mu\nu$ production in $p$+Pb collisions at $\sqrt{s_{_\text{NN}}}=5.02$ TeV using 28.1 $\pm$ 0.3 nb$^{-1}$. The pseudorapidity differential cross section is presented for muons from inclusive $W\rightarrow\mu\nu$ as well as for $W^{+}\rightarrow\mu^{+}\nu$ and $W^{-}\rightarrow\mu^{-}\nu$ separately. The differences between the charge separated cross sections are particularly sensitive to nuclear modification of the Parton Distribution Function in the Pb ion, and this is studied by calculating the lepton charge asymmetry. In addition to the cross sections, which are integrated over all impact parameters, the centrality dependence of $W\rightarrow\mu\nu$ production is measured. It is analyzed within the framework of a standard Glauber model and a model including extensions for fluctuations of the underlying N-N scattering cross section. Results are compared with a baseline model composed of 82$\sigma(pp\rightarrow W+X)$ + 126$\sigma(pn\rightarrow W+X)$ calculated in NLO pQCD.