Composite scalar Dark Matter from vector-like $SU(2)$ confinement

TL;DR

This paper explores a composite scalar dark matter candidate arising from a vector-like $SU(2)$ confinement model, analyzing its relic abundance, detection constraints, and prospects for future searches.

Contribution

It introduces a novel scalar T-baryon dark matter candidate from a vector-like $SU(2)$ confinement model and evaluates its phenomenological viability.

Findings

T-baryon mass estimated to be around 1 TeV.

T-baryon evades direct detection via suppressed Z coupling.

Higgs-mediated interactions provide the main detection channel.

Abstract

A toy-model with $SU(2)_{\rm TC}$ dynamics confined at high scales $\Lambda_{\rm TC}\gg 100$ GeV enables to construct Dirac UV completion from the original chiral multiplets predicting a vector-like nature of their weak interactions consistent with electroweak precision tests. In this work, we investigate a potential of the lightest scalar baryon-like (T-baryon) state $B^0=UD$ with mass $m_B\gtrsim 1$ TeV predicted by the simplest two-flavor vector-like confinement model as a Dark Matter (DM) candidate. We show that two different scenarios with the T-baryon relic abundance formation before and after the electroweak (EW) phase transition epoch lead to symmetric (or mixed) and asymmetric DM, respectively. Such a DM candidate evades existing direct DM detection constraints since its vector coupling to $Z$ boson absents at tree level, while one-loop gauge boson mediated contribution is shown to be vanishingly small close to the threshold. The dominating spin-independent (SI) T-baryon--nucleon scattering goes via tree-level Higgs boson exchange in the $t$-channel. The corresponding bound on the effective T-baryon--Higgs coupling has been extracted from the recent LUX data and turns out to be consistent with naive expectations from the light technipion case $m_{\tilde \pi}\ll \Lambda_{\rm TC}$. The latter provides the most stringent phenomenological constraint on strongly-coupled $SU(2)_{\rm TC}$ dynamics so far. Future prospects for direct and indirect scalar T-baryon DM searches in astrophysics as well as in collider measurements have been discussed.