Associated Production of CP-odd and Charged Higgs Bosons at Hadron Colliders

TL;DR

This work investigates the MSSM prediction for the associated production of a CP-odd Higgs A and a charged Higgs H± at hadron colliders via q q' → W* → AH±. Owing to the MSSM mass relation M_{H^±}^2 = M_A^2 + m_W^2 and a gauge-fixed WAH coupling, the Born cross section depends only on M_A, enabling a clean test of the MSSM through the product of decay BRs, or bounding it if no signal is observed. A detailed LO/NLO cross-section discussion, plus a one-loop electroweak analysis, shows corrections are typically small, preserving the predictive power of the Born rate. A parton-level Monte Carlo study at the LHC for A→bb and H±→τν (τ→πν) demonstrates feasible mass reconstruction of A and H± and the potential to constrain MSSM BR-products as a function of M_A, with realistic detector effects considered. The approach provides a robust, parameter-light probe of the MSSM Higgs sector and motivates further studies at future high-energy colliders.

Abstract

In the Minimal Supersymmetric Standard Model, the masses of the charged Higgs boson ($H^\pm$) and the CP-odd scalar ($A$) are related by $M_{H^+}^2=M_A^2+m_W^2$ at the Born level. Because the coupling of $W^-$-$A$-$H^+$ is fixed by gauge interaction, the Born level production rate of $q \bar q' \to W^{\pm \ast} \to A H^\pm$ depends only on one supersymmetry parameter -- the mass ($M_A^{}$) of $A$. We examine the sensitivity of the LHC to this signal event in the $A(\ra b {\bar b})H^+(\ra τ^+ ν_τ)$ and $A(\ra b {\bar b})H^+(\ra t {\bar b})$ decay channels. We illustrate how to test the mass relation between $A$ and $H^+$ in case that the signal is found. If the signal is not found, the product of the decay branching ratios of $A$ and $H^\pm$ predicted by the MSSM is bounded from above as a function of $M_A$.

Figures (13)

• Figure 1: The LO (dotted lines) and NLO QCD (solid lines) cross sections of the $AH^+$ and $AH^-$ pairs as a function of $M_A^{}$ at the Tevatron (a 1.96 TeV $p \bar{p}$ collider), and the LHC (a 14 TeV $p p$ collider). The cross sections for $AH^+$ and $AH^-$ pair productions coincide at the Tevatron for being a $p \bar{p}$ collider.
• Figure 2: The $K$-factor, $K^{(1)}(s)$, of the constituent process $q {\bar{q}'} \rightarrow H^+A$ for $M_A^{}=90$ GeV, as a function of the invariant mass $\sqrt{s}$ of $q {\bar{q}'}$. The solid lines correspond to the top and bottom quark contribution. The cases where the squark-loop contribution is included are described by the dotted lines for those without stop mixing (Set 1 and Set 2) and by dashed lines for those with maximal stop mixing (Set 3 and Set 4), respectively.
• Figure 3: Distributions of $\not{}{ }{E}_T$, $p_T^b$, $p_T^{\pi}$ and $m_{b\overline{b}}$ at the LHC for Case A, with $M_A=101$ GeV and $M_H=113$ GeV in the $b {\bar{b}} \pi^+ {\not{}{ } E_T}$ channel, after imposing the basic cuts specified in Eq. (\ref{['eq:basic']}).
• Figure 4: $\tau^+$ is left-handedly polarized in $H^+ \rightarrow \tau^+\nu$, and right-handedly polarized in $W^+ \rightarrow \tau^+\nu$. Moreover, $\pi^+$ momentum depends on the polarization of $\tau^+$. (The thin arrow represents the moving direction, and the bold arrow represents the spin direction of the particle.) Similar plots for $\tau^-$ are also shown in the right four diagrams.
• Figure 5: Distributions of $m_{b\overline{b}}$ for Case A, with $M_A=101$ GeV and $M_H=113$ GeV in the $b {\bar{b}} \pi^+ {\not{}{ } E_T}$ channel, after imposing the additional cuts: $\not{}{ } E_T > 50$ GeV and $p_T^{\pi} > 40$ GeV.