Strange crossings in the proton sea*

Net strangeness in the proton is zero, but the momentum distributions of the s and sbar quarks in the proton sea may differ. This strangeness asymmetry, s(x)-sbar(x), arises from fluctuations of the proton into meson-baryon pairs. We use a Fock state expansion of the proton, in terms of K-Lambda, K-Sigma,  K^*-Lambda, and K^*-Sigma states, to represent this “strange meson cloud”, in which s quarks reside in baryons and sbar quarks in mesons. We determine the momentum distributions of the strange quarks in a hybrid convolution model, in which the fluctuations are represented either by light-cone or meson-baryon splitting functions.  For the parton distributions of the s(sbar) quarks in the “bare” baryons(mesons) of the Fock states, we use light cone wave functions or our statistical model, which expands the bare hadrons in terms of quark-gluon states. We present our results for strangeness asymmetry, which include one or more zero crossing points, and compare them to global parton distributions and other theoretical work.