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QCD-Electroweak First-Order Phase Transition in a Supercooled Universe
Satoshi Iso1, Pasquale D Serpico2, Kengo Shimada2
1Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK) and Graduate University for Advanced Studies (SOKENDAI), Oho 1-1, Tsukuba, Ibaraki 305-0801, Japan.
Physical Review Letters
|October 21, 2017
Summary
Classically conformal electroweak dynamics can alter early Universe evolution. A first-order quantum chromodynamics (QCD) phase transition can trigger electroweak symmetry breaking, with implications for cosmology and particle physics.
Area of Science:
- Particle Physics
- Cosmology
- Quantum Chromodynamics
Background:
- The Standard Model's electroweak sector is typically described by non-conformal dynamics.
- Classically conformal dynamics in the electroweak sector may lead to a first-order electroweak phase transition, differing from the Standard Model.
- The early Universe's evolution is sensitive to the nature of electroweak symmetry breaking.
Purpose of the Study:
- To investigate a scenario where a first-order quantum chromodynamics (QCD) phase transition triggers electroweak symmetry breaking.
- To derive the conditions necessary for this alternative cosmological evolution.
- To explore the implications of this scenario for particle physics and cosmology.
Main Methods:
- Analysis of classically conformal dynamics in the electroweak sector.
- Derivation of necessary conditions for a QCD phase transition preceding electroweak symmetry breaking.
- Utilizing the classically conformal B-L model as a specific example.
Main Results:
- A scenario is identified where a first-order, six-massless-quark QCD phase transition precedes and triggers electroweak symmetry breaking.
- The necessary conditions for this sequence of events are derived.
- The model predicts relatively light, weakly coupled particles.
Conclusions:
- Classically conformal electroweak dynamics offer an alternative to Standard Model cosmology.
- The proposed scenario has significant implications for electroweak baryogenesis, dark matter production, and gravitational wave generation.
- The predicted light particles may be discoverable in collider experiments.
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