Charged Composite Scalar Dark Matter

TL;DR

This paper proposes a composite pseudo Nambu-Goldstone boson model where the dark matter candidate is a complex scalar stabilized by a $U(1)_{DM}$ symmetry, with implications for relic density, collider phenomenology, and direct detection.

Contribution

It introduces a calculable composite pNGB dark matter model with improved relic density computation and explores its collider and direct detection signatures.

Findings

Identifies a parameter space with $f=1.4$ TeV and $m_\chi$ between 200-400 GeV satisfying current bounds.

Shows that including top partner effects relaxes tension with direct detection constraints.

Predicts exotic top partners charged under $U(1)_{DM}$ with testable LHC signatures.

Abstract

We consider a composite model where both the Higgs and a complex scalar $\chi$, which is the dark matter (DM) candidate, arise as light pseudo Nambu-Goldstone bosons (pNGBs) from a strongly coupled sector with TeV scale confinement. The global symmetry structure is $SO(7)/SO(6)$, and the DM is charged under an exact $U(1)_{\rm DM} \subset SO(6)$ that ensures its stability. Depending on whether the $\chi$ shift symmetry is respected or broken by the coupling of the top quark to the strong sector, the DM can be much lighter than the Higgs or have a weak-scale mass. Here we focus primarily on the latter possibility. We introduce the lowest-lying composite resonances and impose calculability of the scalar potential via generalized Weinberg sum rules. Compared to previous analyses of pNGB DM, the computation of the relic density is improved by fully accounting for the effects of the fermionic top partners. This plays a crucial role in relaxing the tension with the current DM direct detection constraints. The spectrum of resonances contains exotic top partners charged under the $U(1)_{\rm DM}$, whose LHC phenomenology is analyzed. We identify a region of parameters with $f = 1.4\; \mathrm{TeV}$ and $200\;\mathrm{GeV} \lesssim m_\chi \lesssim 400\;\mathrm{GeV}$ that satisfies all existing bounds. This DM candidate will be tested by XENON1T in the near future.