Nonperturbative strange-quark sea from lattice QCD, light-front holography, and meson-baryon fluctuation models

Understand

We demonstrate that a nonzero strangeness contribution to the spacelike electromagnetic form factor of the nucleon is evidence for a strange-antistrange asymmetry in the nucleon's light-front wave function, thus implying different nonperturbative contributions to the strange and antistrange quark distribution functions.

• A recent lattice QCD calculation of the nucleon strange quark form factor predicts that the strange quark distribution is more centralized in coordinate space than the antistrange quark distribution, and thus the strange quark distribution is more spread out in light-front momentum space.
• We show that the lattice prediction implies that the difference between the strange and antistrange parton distribution functions, $s(x)-\bar{s}(x)$, is negative at small-$x$ and positive at large-$x$.
• We also evaluate the strange quark form factor and $s(x)-\bar{s}(x)$ using a baryon-meson fluctuation model and a novel nonperturbative model based on light-front holographic QCD.