Alice meets Boojums in neutron stars: vortices penetrating two-flavor quark-hadron continuity

TL;DR

This paper explores the theoretical possibility of vortices in neutron stars' cores, showing how neutron superfluid vortices can connect with non-Abelian Alice strings in quark matter, revealing complex vortex structures.

Contribution

It introduces the concept of non-Abelian Alice strings and their junctions with neutron vortices, advancing understanding of quark-hadron continuity in neutron star cores.

Findings

Neutron superfluid vortices can connect with non-Abelian Alice strings.

Boojum junctions form where three neutron vortices meet three Alice strings.

Color magnetic fluxes cancel out at the junctions.

Abstract

Alice and Boojums are both representative characters created by Lewis Carroll. We show that they possibly meet in cores of rotating neutron stars. Recent studies of quark-hadron continuity suggest that neutron superfluid matter can connect smoothly to two-flavor symmetric quark matter at high densities. We study how this can be maintained in the presence of the vortices. In the neutron matter, quantized superfluid vortices arise. In the two-flavor dense quark matter, vortices carrying color magnetic fluxes together with fractionally quantized superfluid circulations appear as the most stable configuration, and we call these as the non-Abelian Alice strings. We show that three integer neutron superfluid vortices and three non-Abelian Alice strings of different color magnetic fluxes with total color flux canceled out are joined at a junction called a Boojum.