Presented in this thesis are measurements of W boson production in high energy pp collisions and ep deep inelastic scattering that take place at RHIC and HERA facilities, respectively. These measurements explore the inner structure of the nucleons, in particular, probing the distributions of the light flavor sea which consists of up, down and strange quarks. The W+/W− cross-section ratio, RW , in pp collisions is sensitive to the asymmetry in the ¯d and ¯u flavors in the nucleon sea. This ratio was first measured with the STAR detector at RHIC with the data collected in 2009 and again with the data collected from 2011 to 2013, featuring pp collisions of a center-of-mass energy of √s = 500/510 GeV and an integrated luminosity of ∼ 350 pb−1. The study considered in this thesis further improves the precision of this measurement by analyzing an additional data set collected in 2017 which corresponds to an integrated luminosity of ∼ 350 pb−1. The experimental results are compared to theory predictions generated with various global PDF fits. The measurement performed at HERA searches for the strange quark content in the nucleon via charm production in charged current deep inelastic scattering. This is the first measurement of its kind, using the HERA II data collected with the ZEUS detector. This data set corresponds to e±p collisions at a center-of-mass energy of √s = 318 GeV with an integrated luminosity of 358 pb−1. The results are consistent with expectations from the Standard Model, albeit with large experimental uncertainties arising from the limited statistics. / Physics