Is forward dihadron suppression in proton-nucleus collisions a saturation signal?
In plain words
When a proton hits a gold nucleus, pairs of particles flying forward are less often back-to-back than in proton-proton collisions, which saturation predicts. Other effects, such as extra kicks from ordinary scattering in the nucleus, might also cause it.
Precise statement
STAR measured an A-dependent suppression of the away-side peak of forward $\pi0-\pi0$ azimuthal correlations ($2.6 < \eta < 4.0$) in $p+\mathrm{Al}$ and $p+\mathrm{Au}$ relative to $p+p$ at $\sqrt{s_{NN}} = 200 \mathrm{GeV}$ (STAR, Phys. Rev. Lett. 129, 092501, 2022). Determine whether the suppression and broadening quantitatively require nonlinear gluon dynamics, or are reproduced by linear-evolution calculations with nuclear transverse-momentum broadening, Sudakov resummation and multiparton interactions.
What would settle it
Calculations of both kinds with common inputs confronted with dihadron data in p+A at RHIC and LHC forward rapidities and in e+A at the Electron-Ion Collider.
Related problems
- Special case of Does gluon density saturate at small momentum fraction?