WIMPless Dark Matter and Meson Decays with Missing Energy

TL;DR

This work analyzes a GeV-scale WIMPless dark matter scenario in which a scalar DM particle $X$ couples to Standard Model fermions through a heavy mediator $Y$. It predicts novel signatures in bottomonium decays, including invisible channels $\chi_{b0}\to XX$ and radiative transitions $\Upsilon\to \gamma XX$, and relates these to the spin-independent DM–nucleon cross section $\sigma_{SI}$ and to flavor constraints from $B$ decays and $B_s$ mixing. By deriving decay amplitudes, branching ratios, and collider‑reach estimates, the paper demonstrates that bottomonium measurements at CLEO and future Super‑B factories can probe parameter space relevant for light DM and complement direct-detection experiments. The analysis highlights how flavor and quarkonium observables can test WIMPless models where DM couples preferentially to $b$ quarks, offering a practical avenue to falsify or constrain such scenarios.

Abstract

WIMPless dark matter offers an attractive framework in which dark matter can be very light. We investigate the implications of such scenarios on invisible decays of bottomonium states for dark matter with a mass less than around $5 {\rm GeV}$. We relate these decays to measurements of nucleon-dark matter elastic scattering. We also investigate the effect that a coupling to $s$ quarks has on flavor changing $b\to s$ processes involving missing energy.

Figures (6)

• Figure 1: $t$-channel $b\bar{b}\to XX$ diagram that leads to $\chi_{b0}\to XX$.
• Figure 2: Diagram that leads to spin independent $X$-proton cross section.
• Figure 3: Spin independent $X$-proton cross section as a function of $m_X$ with contours of constant ${\cal B}(\Upsilon(2S)\to \gamma \chi_{b0}\to\gamma XX)$ indicated. The CRESST limit Angloher:2002in is shown in red (solid) while the area between the red (solid) and green (dashed) lines is consistent with the dark matter interpretation of DAMA/LIBRA if dark matter streams are included Gondolo:2005hh.
• Figure 4: Diagram relevant for $B^+\to K^+ XX$.
• Figure 5: The upper limit on $\left|\rho\right|$, defined in Eq. \ref{['eq:rho']}, as a function of $m_X$ from ${\cal B}\left(B^+\to K^+ \bar{\nu}\nu\right)<1.4\times 10^{-5}$:2007zk and from the contribution to $\Delta m_s$ from $X$ and $Y$ exchange being less that the measured value of $17.77\pm0.12~{\rm ps}^{-1}$Abulencia:2006ze for $m_Y=400~{\rm GeV}$.