ΔMW≤10 MeV/c2 at the LHC: a forlorn hope?

At the LHC, the measurement of the W mass with a precision of $\mathcal{O}$(10) MeV/c2 is both mandatory and difficult. In the analysis strategies proposed so far, shortcuts have been made that are justified for proton–antiproton collisions at the Tevatron, but not for proton–proton collisions at the LHC. The root of the problem lies in the inadequate knowledge of parton density functions of the proton. It is argued that in order to reach a 10 MeV/c2 precision for the W mass, more precise parton density functions of the proton are needed, and an LHC-specific analysis strategy ought to be pursued. Proposals are made on both issues.