Determine whether hotspot–hotspot repulsion occurs in the QCD vacuum

Determine whether gluonic hotspots in exclusive diffractive proton scattering exhibit mutual repulsion at the penetration-depth scale predicted for vortices in a type-II dual superconductor.

Background

The extracted Ginzburg–Landau parameter places the effective QCD vacuum description in the type-II regime, where vortex lines are expected to repel over a distance set by the penetration depth. The authors test this prediction by incorporating hotspot–hotspot repulsion into their model and scanning its characteristic length scale.

The available HERA data do not resolve the issue because, near the relevant momentum transfer, geometric fluctuations and saturation-scale fluctuations contribute comparably to the incoherent cross section. The authors suggest that tagging the proton dissociation mass M_Y could separate these contributions: high-M_Y events should emphasize occupancy fluctuations, whereas low-M_Y events should emphasize longer-wavelength geometric modes. Thus, whether the repulsion predicted by the type-II interpretation is physically present remains unresolved.