Conjectures about the Chiral Phase Transition in QCD from Anomalous Multi-Instanton Interactions

To date numerical simulations of lattice QCD have not found a chiral phase transition of first order that is expected to occur for sufficiently light pions. We show how the restoration of an exact global chiral symmetry can strongly decrease the breaking of the approximate, anomalous U_{A}(1) symmetry. This is testable on the lattice through simulations for one through four flavors. In QCD a small breaking of the U_{A}(1) symmetry in the chirally symmetric phase generates novel experimental signals.

Small-x Evolution of the Gluon Generalized Parton Distribution E_{g} of the Nucleon

We study the small-x evolution equation for the gluon generalized parton distribution E_{g} of the nucleon. It is shown that E_{g} at vanishing skewness exhibits the Regge behavior identical to the Balitsky-Fadin-Kuraev-Lipatov pomeron despite its association with nucleon helicity-flip processes. We also consider the effect of gluon saturation and demonstrate that E_{g} gets saturated in the same way as its helicity-nonflip counterpart H_{g}. Our result has a direct impact on the modeling of E_{g} as well as the small-x contribution to nucleon spin sum rules.