  Precision tests of the Standard Model in the Strong and Electroweak sectors
play an important role, among the physics goals of LHC experiments. Because of
the nature of proton-proton processes, observables based on the measurement of
the direction and energy of leptons provide the most precise signatures.
  In the present paper, we concentrate on the angular distribution of leptons
from W to l nu decays in the lepton-pair rest-frame. The vector nature of the
intermediate state imposes that distributions are to a good precision described
by spherical polynomials of at most second order. We argue, that contrary to
general belief often expressed in the literature, the full set of angular
coefficients can be measured experimentally, despite the presence in the final
state of neutrino escaping detection. There is thus no principle difference
with respect to the phenomenology of the Z/gamma to l^+ l^- Drell-Yan process.
  We show also, that with the proper choice of the coordinate frames, only one
coefficient in this polynomial decomposition remains sizable, even in the
presence of one or more high p_T jets. The necessary stochastic choice of the
frames relies on probabilities independent from any coupling constants. In this
way, electroweak effects (dominated by the V-A nature of W couplings to
fermions) can be better separated from the ones of strong interactions. The
separation is convenient for the measurements interpretation.
