Charged Higgs Boson Production in Bottom-Gluon Fusion

TL;DR

This work computes the complete next-to-leading order SUSY-QCD corrections for associated production of a charged Higgs with a top quark via bottom-gluon fusion, and examines the validity of the bottom-parton description. It provides NLO results for both a general two-Higgs-doublet model and the MSSM, showing significant corrections primarily from tanβ-enhanced bottom Yukawa effects (Delta m_b) in the MSSM, while other SUSY-loop contributions are comparatively small. Scale choices and resummation are analyzed to reduce uncertainties, yielding uncertainties ≲20% for the total cross section and stable differential distributions. The findings support the reliability of inclusive bg→tH⁻ predictions for LHC charged Higgs searches and clarify when bottom-parton resummation is essential.

Abstract

We compute the complete next-to-leading order SUSY-QCD corrections for the associated production of a charged Higgs boson with a top quark via bottom-gluon fusion. We investigate the applicability of the bottom parton description in detail. The higher order corrections can be split into real and virtual corrections for a general two Higgs doublet model and into additional massive supersymmetric loop contributions. We find that the perturbative behavior is well under control. The supersymmetric contributions consist of the universal bottom Yukawa coupling corrections and non-factorizable diagrams. Over most of the relevant supersymmetric parameter space the Yukawa coupling corrections are sizeable, while the remaining supersymmetric loop contributions are negligible.

Figures (7)

• Figure 1: The rapidity difference between the final state bottom jet and the center of mass system for exclusive charged Higgs boson production at the LHC, eq.(\ref{['eq:sig_excl']}). The two sets of curves with three different charged Higgs boson masses are given for the physical on-shell bottom mass $4.6\;{\rm GeV}$ as well as for an arbitrarily chosen smaller bottom mass as the infrared regulator.
• Figure 2: Left: the bottom transverse momentum distribution for exclusive charged Higgs boson production at the LHC, eq.(\ref{['eq:sig_excl']}). For all three Higgs masses the curves are given for the physical on-shell bottom mass $4.6\;{\rm GeV}$ as well as for an arbitrarily chosen smaller bottom mass as the infrared regulator. The thin dotted line indicates half the height of the plateau. The absolute normalization of the curves for the two infrared regulators is physical. Both curves coincide for large transverse momenta, where the bottom mass is negligible. Right: in the upper panel the same distribution for a heavy charged Higgs boson, but with the gluon luminosity set to unity ${\cal L}_{gg} \equiv 1$. Below this in the two lower panels the transverse momentum distribution for the bottom quarks in exclusive neutral Higgs boson production $gg \to \bar{b}bH$ for two neutral Higgs boson masses.
• Figure 3: Left: the bottom transverse momentum distribution for exclusive charged Higgs production at the LHC, eq.(\ref{['eq:sig_excl']}). Right: the bottom rapidity distribution for the same process. Again a set of curves with a small infrared regulator is added ($m_b=0.46\;{\rm GeV}$).
• Figure 4: Left: the inclusive production cross section $pp \to tH^-+X$ at the LHC. The dashed and solid lines show the consistent leading order and next-to-leading order results. The dotted line is the total cross section from the exclusive production process, eq.(\ref{['eq:sig_excl']}). To illustrate the enhancement through large logarithms both tree level results are also quoted using the (inappropriate) pole mass for the bottom Yukawa coupling. The range for the next-to-leading order result is given for $\mu_F=\mu_R=m_{\rm av}/4 \cdots 4 m_{\rm av}$. Right: the corresponding consistent $K$ factors for the three values of $\tan\beta=5,10,30$. In the case of $\tan\beta=30$ we show three choices of $\mu = \mu_R = \mu_F$, consistently for leading order and next-to-leading order cross sections.
• Figure 5: The variation of the total inclusive cross section $pp \to tH^-+X$ as a function of the renormalization and factorization scales, around the central value $\mu=m_{\rm av}$, eq.(\ref{['eq:m_av']}). The two panels give the result for two different charged Higgs boson masses, $250\;{\rm GeV}$ and $500\;{\rm GeV}$. The lower end of the curves corresponds to $\mu \sim 10\;{\rm GeV}$. The respective leading order and next-to-leading order curves can be identified at the point where they meet for the central choice $\mu = m_{\rm av}$.