The NNLO gluon fusion Higgs production cross-section with many heavy quarks

TL;DR

This paper calculates the NNLO gluon fusion Higgs production cross-section in models with additional heavy quarks, showing significant enhancement and implications for experimental exclusion limits.

Contribution

It develops an effective theory for Higgs production with many heavy quarks and computes the NNLO Wilson coefficient, extending previous Standard Model calculations.

Findings

Gluon fusion cross-section is increased by a factor of about 9.

Tevatron data can strongly constrain models with extra heavy quarks.

Effective theory accurately describes Higgs production below heavy quark pair thresholds.

Abstract

We consider extensions of the Standard Model with a number of additional heavy quarks which couple to the Higgs boson via top-like Yukawa interactions. We construct an effective theory valid for a Higgs boson mass which is lighter than twice the lightest heavy quark mass and compute the corresponding Wilson coefficient through NNLO. We present numerical results for the gluon fusion cross-section at the Tevatron for an extension of the Standard Model with a fourth generation of heavy quarks. The gluon fusion cross-section is enhanced by a factor of roughly 9 with respect to the Standard Model value. Tevatron experimental data can place stringent exclusion limits for the Higgs mass in this model.