Systematics of Deuteron Smearing Corrections in Global PDF fits

Use of DIS data on light A=2,3 nucleus targets for up and down quark flavor separation at large x crucially depends on the theoretical treatment of nuclear effects such as binding and Fermi motion, and off-shell deformation of the quark and gluon structure of bound nucleons. The amount and precision of available data from JLab 6 and, increasingly, from the JLab 12 experimental programs require a correspondingly precise treatment of nuclear corrections. In this talk, I will discuss recent work that scrutinizes systematic uncertainties in the so-called nuclear smearing, and its applications to global QCD fits of parton distribution functions at large x values.