Abstract
About 80\% of the mass of the present Universe is made up of the unknown (dark matter), while the rest is made up of ordinary matter. It is a very intriguing question why the {\it mass} densities of dark matter and ordinary matter (mainly baryons) are close to each other. It may be hinting the identity of dark matter and furthermore structure of a dark sector. A mirrored world provides a natural explanation to this puzzle. On the other hand, if mirror-symmetry breaking scale is low, it tends to cause cosmological problems. In this letter, we propose a mirrored unification framework, which breaks mirror-symmetry at the grand unified scale, but still addresses the puzzle. The dark matter mass is strongly related with the dynamical scale of QCD, which explains the closeness of the dark matter and baryon masses. Intermediate-energy portal interactions share the generated asymmetry between the visible and dark sectors. Furthermore, our framework is safe from cosmological issues by providing low-energy portal interactions to release the superfluous entropy of the dark sector into the visible sector.
Highlights
Cosmological observations have established that the mass of the present Universe is made up of so-called dark matter (DM) in addition to ordinary matter
We have proposed the mirrored grand unified theory (GUT) framework in which the baryon-DM coincidence is naturally explained
The framework relates the masses of baryon and DM and the number densities
Summary
Cosmological observations have established that the mass of the present Universe is made up of so-called dark matter (DM) in addition to ordinary matter. If DM (dark sector) has nothing to do with the SM baryon (visible sector), it is puzzling why their mass densities are close to each other. As for the mass coincidence, the key ingredient is the correspondence between dynamical scales of each sector: the baryon and DM masses are determined by them Such a correspondence can be achieved once the gauge couplings are related with each other at the GUT scale. The second symmetry breaking in the dark sector provides the intermediate-energy portal interactions and tiny kinetic mixing of visible photon and dark photon. SUSY plays key roles to achieve gauge coupling unification in the visible sector and to ensure the existence of degenerate vacua with various breaking patterns of the GUT gauge group. The last section is devoted to concluding remarks of this article
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