Direct Detection of the Wino- and Higgsino-like Neutralino Dark Matters at One-Loop Level

TL;DR

The paper investigates one-loop gauge corrections to neutralino–nucleon scattering for wino- and Higgsino-like LSPs in the MSSM. It shows that tree-level spin-independent and spin-dependent interactions are strongly suppressed by gaugino–Higgsino mixing, especially when the LSP is close to a weak eigenstate, but that gauge-loop corrections from W-boson diagrams are not similarly suppressed and can meaningfully modify the total cross section. For wino-like LSPs, these loop contributions can yield spin-independent cross sections near 10^{-46}–10^{-47} cm^2 in parameter regions where tree-level terms are small, while Higgsino-like cases experience smaller loop effects. The work highlights the importance of radiative corrections for interpreting direct-detection results and for setting robust expectations for future experiments, while noting substantial hadronic uncertainties and the need for further multi-loop analysis.

Abstract

The neutralino-nucleon (\tildeχ^0-N) scattering is an important process for direct dark matter searches. In this paper we discuss one-loop contributions to the cross section in the wino-like and Higgsino-like LSP cases. The neutralino-nucleon scattering mediated by the Higgs \tildeχ^0\tildeχ^0 and Z\tildeχ^0\tildeχ^0 couplings at tree level is suppressed by the gaugino-Higgsino mixing at tree level when the neutralino is close to a weak eigenstate. The one-loop contribution to the cross section, generated by the gauge interaction, is not suppressed by any SUSY particle mass or mixing in the wino- and Higgsino-like LSP cases. It may significantly alter the total cross section when σ_{\tildeχ^0 N}\sim 10^{-45} cm^2 or less.

Figures (9)

• Figure 1: (a) Diagram contributing to the anomalous Higgs boson vertices of the neutralino and (b) box diagram contributing to the $\tilde{\chi}^0$--$N$ scattering in the case of the wino-like LSP.
• Figure 2: A two-loop diagram contributing to $GG\overline{\tilde{\chi}^0}\tilde{\chi}^0$.
• Figure 3: One-loop induced cross section for spin-independent $\tilde{\chi}^0$--$p$ scattering as a function of $f_{Ts}$ for $a_{\rm eff}=1.0$ and 2.0 in the case of the wino-like LSP. We assume that the tree-level contribution is negligible and the process is induced by the one-loop diagrams. Here, we take $m_{\tilde{\chi}^0}=1600$GeV and the parameter in Table. \ref{['table1']} except for $f_{Ts}$. Also, we use $\tan\beta=10$, $m_A$=1000GeV, $m_{\rm stop}$=2000GeV, and $A_{\rm top}$=0, which determine the light Higgs mass and the mixing angle.
• Figure 4: One-loop induced cross section for spin-independent $\tilde{\chi}^0$--$p$ scattering is presented as a function of $\tan\beta$ and $m_{A}$. The wino-like LSP is assumed. Here, we take $m_{\tilde{\chi}^0}$=1600GeV, $m_{\rm stop}$=2000GeV, $A_{\rm top}$=0, $a_{\rm eff}=1$, and the parameter in Table. \ref{['table1']}.
• Figure 5: Total cross section for spin-independent $\tilde{\chi}^0$--$p$ scattering, $\sigma_{\rm total}$, (left) for the wino-like LSP in the $(\mu, m_A)$ plane. The cross section is depicted in the unit of $10^{-47}$cm$^2$. Here, $M_2=200$ GeV, $M_1/M_2=11t_W^2$, $m_{\tilde{t}}=2$ TeV and $\tan\beta=4(40)$ for upper (lower) plot. $\sigma_{\rm total}$ includes the gauge-loop contributions while the squark exchange contribution at tree level is ignored. In the right, we give the ratio $\sigma_{\rm total}/\sigma_{\rm tree}$ for the same parameters. $\sigma_{\rm tree}$ is the cross section at tree level.