SusHi: A program for the calculation of Higgs production in gluon fusion and bottom-quark annihilation in the Standard Model and the MSSM

Abstract: This article describes the code SusHi (for "Supersymmetric Higgs") which calculates the cross sections $pp/p\bar{p}\rightarrow\phi+X$ in gluon fusion and bottom-quark annihilation in the SM and the MSSM, where $\phi$ is any of the neutral Higgs bosons within these models. Apart from inclusive cross sections up to NNLO QCD, differential cross sections with respect to the Higgs' transverse momentum $p_T$ and (pseudo-)rapidity $y(\eta)$ can be calculated through NLO QCD. In case of gluon fusion, SusHi contains NLO QCD contributions from the third family of quarks and squarks, NNLO corrections due to top-quarks, approximate NNLO corrections due to top-squarks, and electro-weak effects. It supports various renormalization schemes for the sbottom sector and the bottom Yukawa coupling, as well as resummation effects of higher order $\tan\beta$-enhanced sbottom contributions. SusHi provides a link to FeynHiggs for the calculation of the Higgs masses.

• The paper introduces SuShi, a computational tool for accurately calculating Higgs production cross sections in both the SM and MSSM.
• It employs NNLO QCD corrections with soft-gluon resummation for gluon fusion and NLO precision for bottom-quark annihilation processes.
• The modular design enables detailed differential cross-section analyses, supporting precise phenomenological studies at the LHC.

Overview of Higgs Production in the Standard Model and MSSM

The paper under discussion introduces a computational tool, termed "SUSYHiggs" (SuShi), designed for calculating Higgs boson production cross sections in both the Standard Model (SM) and the Minimal Supersymmetric Standard Model (MSSM). The program specifically addresses Higgs production via gluon fusion and bottom-quark annihilation—mechanisms of pivotal importance in current phenomenological analyses, especially in the light of experiments at the Large Hadron Collider (LHC).

Key Components and Methodologies

The primary focus of SuShi is to deliver an accurate evaluation of the cross sections $pp/p\overline{p}\rightarrow\phi+X$ where $\phi$ represents neutral Higgs bosons within the SM and MSSM frameworks. The paper outlines how the code remains modular and supports the computation of inclusive and differential cross sections with respect to the Higgs transverse momentum and rapidity distributions.

1. Gluon Fusion and Corrections:
   • For the gluon fusion process, the code incorporates next-to-next-to-leading order (NNLO) corrections in Quantum Chromodynamics (QCD), with further resummation of soft gluon effects.
   • The effects of electro-weak corrections are also included, which modify the cross sections by up to 8% relative to leading-order computations.
2. Bottom-Quark Annihilation:
   • The process $b\overline{b}\rightarrow \phi$, known as bottom-quark annihilation, is computed up to next-to-leading order (NLO). This is critical for scenarios where the bottom-sector coupling is enhanced, particularly at large $\tan\beta$ values in the MSSM.
3. Renormalization and Parameterization:
   • The tool supports a variety of renormalization schemes for handling the sbottom sector and bottom Yukawa couplings, enabling precise control over theoretical uncertainties and resummation effects, such as those enhanced by $\tan\beta$.

Numerical Results and Claims

One crucial aspect of the paper is the comprehensive incorporation of higher-order corrections and a meticulous evaluation of these effects across potential MSSM scenarios. The inclusion of NNLO corrections and resummed effects for the dominant production mechanisms provides a robust prediction platform, aligning theoretical calculations with the precision demands of current experimental frameworks.

The paper doesn't take a sensationalist view of its contributions but acknowledges the potential discrepancies arising from different renormalization schemes or parameter choices, especially within the context of MSSM. The authors suggest their program can produce results consistent with alternative codes but highlight the unique feature of offering extensive differential cross-sectional outputs, aiding detailed phenomenological studies.

Implications and Future Directions

Despite being a niche computational tool, the impact of SuShi is noteworthy in high-energy physics communities focusing on Higgs phenomenology. It facilitates advanced simulations required to interpret LHC data and to explore beyond-Standard Model (BSM) physics, which could reveal signatures of supersymmetry (SUSY).

Future developments in the field would likely involve:

• Extending the capabilities of SuShi to incorporate new physical insights or experimental results.
• Enhancing the program's interface with other computational packages like FeynHiggs, to streamline workflows and increase computational reliability.
• Investigating additional processes or expanding upon the precision of current computations as the experimental precision continues to improve.

Conclusion

This paper outlines an essential tool for Higgs boson production analysis in the SM and MSSM, providing critical computational support for theoretical predictions in line with experimental needs. The code reflects a mature understanding of particle physics phenomena and computational methods, underlining the ongoing demand for precise and adaptable theoretical tools in advancing particle physics research.