Speaker
Description
In this talk, I will show that a polarized nucleon generically carries a spin-aligned dipole distribution of QCD topological charge, despite having zero total topological charge. This structure follows model-independently from the symmetry properties of the local topological charge density. Through the anomalous flavor-singlet axial Ward identity, its dipole strength is directly related to the flavor-singlet axial charge of the nucleon.
I will also demonstrate how this topological dipole is dynamically realized in a two-flavor chiral soliton model incorporating vector mesons and the axial anomaly. In heavy-ion collisions, magnetic-field-induced spin polarization may align the dipoles across events, generating directed-flow-like asymmetries in eta and eta-prime production. Such an effect would offer a qualitatively new signature of local CP-odd QCD structure, complementary to the chiral magnetic effect, since it does not require a fluctuating net topological charge. Possible probes through exclusive eta and eta-prime production will also be discussed.
