# Hidden sector behind the CKM matrix

## TL;DR

This paper proposes a hidden sector model where new particles at the TeV scale mediate quark flavor violation, explaining the CKM matrix and providing a dark matter candidate with specific properties and detectable signals.

## Contribution

It introduces a simple scenario linking the CKM matrix to a hidden sector that also contains a dark matter candidate, with explicit predictions for DM mass and couplings.

## Key findings

- Dark matter mass around the TeV scale
- Yukawa couplings between DM and quarks are between 0.01 and 1
- Predicted spin-independent DM cross section is about 10^{-9} pb

## Abstract

The small quark mixing, described by the Cabibbo-Kobayashi-Maskawa (CKM) matrix in the Standard Model, may be a clue to reveal new physics around the TeV scale. We consider a simple scenario that extra particles in a hidden sector radiatively mediate the flavor violation to the quark sector around the TeV scale and effectively realize the observed CKM matrix. The lightest particle in the hidden sector, whose contribution to the CKM matrix is expected to be dominant, is a good dark matter (DM) candidate, so we focus on the contribution, and discuss the DM physics. In this scenario, there is an explicit relation between the CKM matrix and flavor violating couplings, such as four-quark couplings, because both are radiatively induced by the particles in the hidden sector. Then, we can explicitly find the DM mass region and the size of Yukawa couplings between the DM and quarks, based on the study of flavor physics and DM physics. In conclusion, we show that DM mass in our scenario is around the TeV scale, and the Yukawa couplings are between ${\cal O}(0.01)$ and ${\cal O}(1)$. The spin-independent DM scattering cross section is estimated as ${\cal O}(10^{-9})$ [pb]. An extra colored particle is also predicted at the ${\cal O}(10)$ TeV scale.