Calculation of strangeness asymmetry in the proton sea*

The Heisenberg uncertainty principle allows the proton to have a strange sea, by way of splitting into a K or K* meson and a Lambda or Sigma baryon. The net strangeness of the proton is zero, but the splitting gives rise to an asymmetry in the momentum distributions s(x) and sbar(x) of the strange and anti-strange quarks. Our goal is to understand this asymmetry in terms of the splitting process and the structure of the mesons and baryons. We determine the momentum distributions with both a Meson Cloud Model (MCM) and a Light Cone Model (LCM). We use the MCM for the fluctuation functions f, which represent the probability that the proton will split into a meson-baryon pair. We use the LCM to calculate the parton distribution functions (PDFs) for the strange quarks in the meson and baryon in terms of two-body wave functions. Then s(x) and sbar(x) are found from a convolution of the splitting functions f and the meson and baryon PDFs. We find that the strangeness asymmetry s(x)-sbar(x) has two crossings, or changes of sign. We study the dependence of the asymmetry on the parameters of our model, and compare our results to global PDF analyses and experimental constraints on proton strangeness.