Oct 2023 - Sep 2024

Small-x resummation at the LHC in the HELL framework

by Federico Silvetti




High-energy (or small-x) logarithms are a class of QCD corrections arising in hadron scattering processes. These are enhanced when the collider centre-of-mass energy is much larger than the typical hard scattering scale.
Under this condition, fixed order perturbation theory breaks down. Thus, both QCD cross-sections and DGLAP evolution kernels  require all-order resummation to restore predictivity.
Several approaches are possible to perform this task. Traditionally, the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation enables high-energy resummation in the DGLAP evolution kernels. Similarly, transverse momentum-dependent factorisation schemes allow performing the same operation in hadron cross-sections. However, both this approaches require cumbersome manipulations in adjoint coordinate spaces.
Instead, a direct space formulation, available in the public code High-Energy Large Logarithms (HELL), was recently made available. This talk will give an overview of the latter formalism and discuss the phenomenological impact of resummation in PDF determination, as well as some LHC observables, namely  Higgs production in gluon fusion and Heavy-quark pair production cross-sections.