Higgs production in gluon fusion beyond NNLO

Abstract

We construct an approximate expression for the cross section for Higgs production in gluon fusion at next-to-next-to-next-to-leading order (N$^3$LO) in $α_s$ with finite top mass. We argue that an accurate approximation can be constructed by exploiting the analiticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummations. We support our argument with an explicit comparison of the approximate and the exact expressions up to the highest (NNLO) order at which the latter are available. We find that the approximate N$^3$LO result amounts to a correction of 16% to the NNLO QCD cross section for production of a 125 GeV Higgs at the LHC (8 TeV), larger than previously estimated, and it significantly reduces the scale dependence of the NNLO result.

Results also provided at muf=mh/2 (Tab.1, Eq.4); scale dependence (Fig. 8) in extended range; comparison to previous collinear improvement added (Figs 1, 2, 8); comparison to resummed results added (Sec.4). Ref. [29] added. Published in Nucl. Phys. B. Figs. 4, 5, 6 and 8, last line of Tab. 1 and Eqs. (4.1), (4.2) updated after bug correction in ggHiggs v1.9. Conclusions unaffected