Abstract
Non-Abelian dark gauge forces that do not couple directly to ordinary matter may be realized in nature. The minimal form of such a dark force is a pure Yang-Mills theory. If the dark sector is reheated in the early universe, it will be realized as a set of dark gluons at high temperatures and as a collection of dark glueballs at lower temperatures, with a cosmological phase transition from one form to the other. Despite being dark, the gauge fields of the new force can connect indirectly to the Standard Model through non-renormalizable operators. These operators will transfer energy between the dark and visible sectors, and they allow some or all of the dark glueballs to decay. In this work we investigate the cosmological evolution and decays of dark glueballs in the presence of connector operators to the Standard Model. Dark glueball decays can modify cosmological and astrophysical observables, and we use these considerations to put very strong limits on the existence of pure non-Abelian dark forces. On the other hand, if one or more of the dark glueballs are stable, we find that they can potentially make up the dark matter of the universe.
Highlights
New gauge forces may be realized in nature beyond the SUð3Þc × SUð2ÞL × Uð1ÞY structure of the standard model (SM)
If the dark sector is reheated in the early Universe, it will be realized as a set of dark gluons at high temperatures and as a collection of dark glueballs at lower temperatures, with a cosmological phase transition from one form to the other
In this work we have investigated the cosmological constraints on non-Abelian dark forces with connector operators to the SM
Summary
New gauge forces may be realized in nature beyond the SUð3Þc × SUð2ÞL × Uð1ÞY structure of the standard model (SM). The requirement of gauge invariance in theories of non-Abelian dark forces implies that the new gauge vector bosons can only couple to the SM through nonrenormalizable operators [39,40]. We assume inflation (or something like it) followed by preferential reheating to the visible sector to a temperature above the confinement scale but below that of the connectors With these assumptions, we find very strong limits on non-Abelian dark forces. IV we study the cosmological evolution of the dark gauge theory and we compute glueball yields both with and without connector operators Some technical details about gluon thermalization and the cosmological and astrophysical bounds we apply are collected in Appendixes A and B
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