Theoretical uncertainties in the MSSM Higgs boson mass calculation

TL;DR

This paper estimates the theoretical uncertainties in predicting the MSSM Higgs boson mass due to higher-order corrections, comparing different computational approaches and providing an improved hybrid method for various SUSY scales.

Contribution

It introduces a hybrid approach combining fixed-order and EFT methods, offering more precise uncertainty estimates across SUSY scales in the MSSM Higgs mass calculation.

Findings

Hybrid approach yields uncertainties up to ~1.5 GeV for large stop mixing.

Uncertainty reduces in the hybrid approach at intermediate scales.

Enhanced uncertainties observed when gluino is much heavier than scalar top quarks.

Abstract

The remaining theoretical uncertainties from unknown higher-order corrections in the prediction for the light Higgs-boson mass of the MSSM are estimated. The uncertainties associated with three different approaches that are implemented in the publicly available code FeynHiggs are compared: the fixed-order diagrammatic approach, suitable for low SUSY scales, the effective field theory (EFT) approach, suitable for high SUSY scales, and the hybrid approach which combines the fixed-order and the EFT approaches. It is demonstrated for a simple single-scale scenario that the result based on the hybrid approach yields a precise prediction for low, intermediate and high SUSY scales with a theoretical uncertainty of up to $\sim 1.5$ GeV for large stop mixing and $\sim 0.5$ GeV for small stop mixing. The uncertainty estimate of the hybrid calculation approaches the uncertainty estimate of the fixed-order result for low SUSY scales and the uncertainty estimate of the EFT approach for high SUSY scales, while for intermediate scales it is reduced compared to both of the individual results. The estimate of the theoretical uncertainty is also investigated in scenarios with more than one mass scale. A significantly enhanced uncertainty is found in scenarios where the gluino is substantially heavier than the scalar top quarks. The uncertainty estimate presented in this paper will be part of the public code FeynHiggs.