Asymmetric preheating

2021

J. High Energ. Phys.

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The Bogoliubov transformation in cosmological particle production can be explained by the Stokes phenomena of the corresponding ordinary differential equation. The calculation becomes very simple as far as the solution is described by a special function. Otherwise, the calculation requires more tactics, where the Exact WKB (EWKB) may be a powerful tool. Using the EWKB, we discuss cosmological particle production focusing on the effect of more general interaction and classical scattering. The classical scattering appears when the corresponding scattering problem of the Schrödinger equation develops classical turning points on the trajectory. The higher process of fermionic preheating is also discussed using the Landau-Zener model.

Section: Conclusion and Discussionmentioning

confidence: 99%

The exact WKB for cosmological particle production

2021

J. High Energ. Phys.

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“…In Ref. [16], we have shown that the "eigenstates" are preserving matter-antimatter asymmetry but they are mixed by the Berry connection. In this case, the phases in the Berry transformation are functions of ω φ , ǫ R , ω η and g. Therefore, in this model, one can expect that a time-dependent ω φ can generate matter-antimatter asymmetry, since it may change the phase parameter asθ i =ω φ (∂θ i /∂ω φ ).…”

Section: E Majorana Fermions For the Simplest Extensionmentioning

confidence: 99%

“…In Ref. [16], we showed a numerical calculation to show that the matter-antimatter asymmetry is generated in this model. Viewing with the "eigenstates"(Ψ E ), the Berry connection causes mixing between "eigenstates" accompanied by the CP phase, which is time dependent, to generate the interference between states.…”

Section: E Majorana Fermions For the Simplest Extensionmentioning

confidence: 99%

Baryogenesis from the Berry phase

2019

Phys. Rev. D

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The spontaneous baryogenesis scenario explains how a baryon asymmetry can develop while baryon violating interactions are still in thermal equilibrium. However, generation of the chemical potential from the derivative coupling is dubious since the chemical potential may not appear after the Legendre transformation. The geometric phase (Pancharatnam-Berry phase) results from the geometrical properties of the parameter space of the Hamiltonian, which is calculated from the Berry connection. In this paper, using the formalism of the Berry phase, we show that the chemical potential defined by the Berry connection is consistent with the Legendre transformation. The framework of the Berry phase is useful in explaining the mathematical background of the spontaneous baryogenesis and also in calculating the asymmetry of the nonthermal particle production in time-dependent backgrounds. Using the formalism, we show that the mechanism can be extended to more complex situations. PACS numbers: 98.80Cq 4 See also Appendix B 5 Here, R in U (R) represents arbitrary parameters.

“…However, this naive speculation fails in the present model. One can calculate the behavior of |β| 2 (both numerically and analytically [19]) 1 to find that the evolution of |β h | 2 and |β g | 2 are identical in this case, resulting no asymmetry production. From this simple model, one can understand why μ = 0 (i.e, a time-dependent chemical potential) is needed for the asymmetry production.…”

Section: Introductionmentioning

confidence: 99%

The exact WKB and the Landau-Zener transition for asymmetry in cosmological particle production

2022

J. High Energ. Phys.

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Cosmological particle production by a time-dependent scalar field is common in cosmology. We focus on the mechanism of asymmetry production when interaction explicitly violates symmetry and its motion is rapid enough to create particles by itself. Combining the exact WKB analysis and the Landau-Zener transition, we point out that perturbation before the non-perturbative analysis may drastically change the structure of the Stokes lines of the theory. The Exact WKB can play an important role in avoiding such discrepancies.