<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>Dear all, Fernanda Steffens is visiting the Theory Center,</div><div>and she kindly accepted to give a seminar before she leaves.<br><br class="Apple-interchange-newline"><span style="font-size: 13px;">Theory Center Seminar</span><br><span style="font-size: 13px;">Wednesday, Nov. 30, 2016</span><br><span style="font-size: 13px;">2:00 p.m.</span><br><span style="font-size: 13px;">CEBAF Center, Room </span><font size="2">L102 </font><br><font color="#0f61c8"><br></font><b><span style="font-size: 15px;">Fernanda Steffens (DESY)</span></b><br><b><span style="font-size: 15px;">Title: "Direct Calculation of
PDFs in Lattice QCD"</span></b><br><font color="#0f61c8"><br></font><span style="font-size: 14px;">Abstract: </span><br><span style="orphans: 2; white-space: pre-wrap; widows: 2;">Parton distributions are usually defined as light-cone correlations in the nucleon. Until recently, however, it was not possible to calculate the distributions in lattice QCD because, unlike spatial correlations, one cannot simulate light-cone correlations in a Euclidian lattice. In 2013, Ji proposed a way to circumvent this restriction, through the use of quark quasi-distributions which are defined as purely spatial correlations. Although they are not the physical distributions, the quark quasi-distributions are related to the quark distributions through a perturbative calculation. Within this procedure, a direct calculation of the distributions in lattice QCD became a possibility, and we present here a high statistics analysis of the x-dependence of the bare unpolarized, helicity and transversity iso-vector parton distribution functions (PDFs) from lattice calculations employing (maximally) twist</span><br><span style="orphans: 2; white-space: pre-wrap; widows: 2;">ed mass fermions. The x-dependence of the calculated PDFs resembles those of the phenomenological parameterizations, a feature that makes this approach promising despite the lack of a full renormalization program for them.</span><br><font color="#0f61c8"><br></font></div></body></html>