Inferring the initial condition for the Balitsky-Kovchegov equation

Abstract

We apply Bayesian inference to determine the posterior likelihood distribution for the parameters describing the initial condition of the small-$x$ Balitsky-Kovchegov evolution equation at leading logarithmic accuracy. The HERA structure function data is found to constrain most of the model parameters well. In particular, we find that the HERA data prefers an anomalous dimension $\gamma \approx 1$ unlike in previous fits where $\gamma >1$ which led to e.g. the unintegrated gluon distribution and the quark-target cross sections not being positive definite. The determined posterior distribution can be used to propagate the uncertainties in the non-perturbative initial condition when calculating any other observable in the Color Glass Condensate framework. We demonstrate this explicitly for the inclusive quark production cross section in proton-proton collisions and by calculating predictions for the nuclear modification factor for the $F_2$ structure function in the EIC and LHeC/FCC-he kinematics.

"v2 matches the published version"

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Cited by in corpus (8)

• Energy dependent nuclear suppression from gluon saturation in exclusive vector meson production
• Transverse Energy-Energy Correlators in the Color-Glass Condensate at the Electron-Ion Collider
• Initial condition for the Balitsky-Kovchegov equation at next-to-leading order
• Single spin asymmetry in forward $pA$ collisions from Pomeron-Odderon interference
• Determination of the initial condition for the Balitsky-Kovchegov equation with transformers
• A numerical implementation of the NLO DIS structure functions in the dipole picture
• Color-glass condensate beyond the Gaussian approximation
• Reconstruction of the Dipole Amplitude in the Dipole Picture as a mathematical Inverse Problem