# Double Higgs boson production at NLO: combining the exact numerical result and high-energy expansion

## TL;DR

This paper enhances predictions for Higgs boson pair production at NLO by combining exact numerical results with high-energy expansions, improving accuracy for boosted Higgs studies at current and future colliders.

## Contribution

It introduces a method to merge exact NLO calculations with high-energy expansions using Padé approximations, extending the validity of virtual corrections across phase space.

## Key findings

- Extended the virtual matrix element grid to higher transverse momenta.
- Provided improved NLO predictions for 14 TeV and 100 TeV colliders.
- Made the updated computational grid publicly available.

## Abstract

We consider the next-to-leading order QCD corrections to Higgs boson pair production, using our recent calculation of the form factors in the high-energy limit. We compute the virtual corrections to the partonic cross section, applying Pad\'e approximations to extend the range of validity of the high-energy expansion. This enables us to compare to the exact numerical calculation in a significant part of the phase space and allows us to extend the virtual matrix element grid, based on the exact numerical calculation, to larger values of the (partonic) transverse momentum of the Higgs boson, which is important for boosted Higgs studies. Improved predictions for hadron colliders with centre-of-mass energies of $14\ \mathrm{TeV}$ and $100\ \mathrm{TeV}$ are presented. The updated grid is made publicly available.