31st International Workshop on Deep Inelastic Scattering

Inferring the Initial Condition for the BK Equation

Non programmé

20m

Maison MINATEC, Grenoble, FRANCE

Regular parallel talk WG2: Small-x, Diffraction and Vector Mesons

Orateur

Carlisle Aurabelle Casuga (University of Jyväskylä)

Description

In this work, we constrain the initial condition for the leading order Balitsky-Kovchegov (BK) evolution equation with an uncertainty estimate by applying Bayesian inference.
The BK equation describes the high-energy evolution of the scattering of a quark - antiquark dipole and a proton or a CGC field. The determined initial condition is then sensitive to the non-perturbative structure of the proton. We found that inclusive DIS $ep$ scattering cross section data of HERA in the small-$x$ region constrain the parameters describing the initial condition of the BK equation very well. This analysis obtained an anomalous dimension $\gamma \sim 1$ while previous fits found $\gamma >1$ which causes, for example, the unintegrated gluon distribution and quark-target cross sections to have negative values. The resulting posterior distributions can, then, be used to propagate uncertainties to calculations of other observables within the CGC framework that use the non-perturbative BK initial condition; explicit examples of which, we demonstrate in this talk. The work foresees an extension to the next-to-leading order correction for which our Bayesian setup is, readily, computationally efficient enough to do.