# Surprises from Complete Vector Portal Theories: New Insights into the Dark Sector and its Interplay with Higgs Physics

## TL;DR

This paper explores UV complete theories extending the Standard Model with a new U(1) gauge symmetry, revealing novel phenomenological insights into dark matter interactions, gauge anomaly constraints, and the interplay with Higgs physics.

## Contribution

It provides a comprehensive analysis of anomaly constraints and dark matter phenomenology in U(1) extended models, highlighting new relations and suppression mechanisms.

## Key findings

- Dark matter annihilation to Zh is p-wave suppressed.
- Gauge anomaly cancellation imposes charge relations and a minimum number of dark fermions.
- The interplay between dark matter, vector bosons, and Higgs physics is natural and generic.

## Abstract

We study UV complete theories where the Standard Model (SM) gauge group is extended with a new abelian $U(1)$, and the field content is augmented by an arbitrary number of scalar and fermion SM singlets, potentially including dark matter (DM) candidates. Considerations such as classical and quantum gauge invariance of the full theory and S-matrix unitarity, not applicable within a simplified model approach, are shown to have significant phenomenological consequences. The lack of gauge anomalies leads to compact relations among the $U(1)$ fermion charges, and puts a lower bound on the number of dark fermions. Contrary to naive expectations, the DM annihilation to Zh is found to be p-wave suppressed, as hinted by perturbative unitarity of S-matrix, with dramatic implications for DM thermal relic density and indirect searches. Within this framework, the interplay between dark matter, new vector boson and Higgs physics is rather natural and generic.