Reviving quark nuggets as a candidate for dark matter

TL;DR

This paper proposes a new mechanism involving spontaneous CP violation during the quark-gluon plasma phase that can produce quark and antiquark nuggets, potentially serving as dark matter candidates within the Standard Model.

Contribution

It introduces a novel process for baryon-antibaryon segregation via CP-violating scattering on Z(3) domain walls, leading to quark nuggets as dark matter candidates.

Findings

Large baryon and anti-baryon concentrations can form in the early universe.

Quark and antiquark nuggets can be generated without new physics beyond the Standard Model.

The mechanism is independent of the quark-hadron transition order.

Abstract

We discuss a novel mechanism for segregation of baryons and anti-baryons in the quark-gluon plasma phase which can lead to formation of quark and antiquark nuggets in the early universe, irrespective of the order of the quark-hadron phase transition. This happens due to CP violating scattering of quarks and antiquarks from moving $Z(3)$ domain walls. CP violation here is spontaneous in nature and arises from the nontrivial profile of the background gauge field ($A_{0}$ ) between different $Z(3)$ vacua. We study the effect of this spontaneous CP violation on the baryon transport across the collapsing large $Z(3)$ domain walls (which can arise in the context of certain low energy scale inflationary models). Our results show that this CP violation can lead to large concentrations of baryons and anti-baryons in the early universe. The quark and antiquark nuggets, formed by this alternate mechanism, can provide a viable dark matter candidate within standard model without violating any observational constraints.