Primordial lepton oscillations and baryogenesis

2018

J. High Energ. Phys.

Self Cite

The possibility of generating the baryon asymmetry of the Universe via flavor oscillation in the early Universe is discussed. After the inflation, leptons are born in some states, travel in the medium, and are eventually projected onto flavor eigenstates due to the scattering via the Yukawa interactions. By using the Lagrangian of the Standard Model with the Majorana neutrino mass terms, llHH, we follow the time evolution of the density matrices of the leptons in this very first stage of the Universe and show that the CP violation in the flavor oscillation can explain the baryon asymmetry of the Universe. In the scenario where the reheating is caused by the decay of the inflaton into the Higgs bosons, the baryon asymmetry is generated by the CP phases in the Pontecorvo-Maki-Nakagawa-Sakata matrix and thus can be tested by the low energy neutrino experiments. arXiv:1807.06582v2 [hep-ph]

“…In general, after the inflation the Universe has experienced a thermalization era called reheating. The baryogenesis at this stage is investigated recently [3,4,5,6]. (See also Refs.…”

Section: Introductionmentioning

confidence: 99%

Leptogenesis via neutrino oscillation magic

Hamada

Kitano

2018

J. High Energ. Phys.

Self Cite

“…T R 100 TeV, that all the interaction rates via Standard Model Yukawa couplings are faster than the expansion rate. 3 Under this most dangerous circumstance for the wash out, one can obtain four possible mass patterns to evade the wash out:…”

Section: Implications On Neutrino Physicsmentioning

confidence: 99%

“…Case 2 For the estimation of the total neutrino mass we use results in a global analysis of neutrino oscillation measurements [32]. 3 If this assumption is removed, some of the charged lepton Yukawa coupling can be neglected when the washout is effective. There can be flavor-dependent lepton symmetry, and thus some component of ∆ vis can not be washed out.…”

Section: Implications On Neutrino Physicsmentioning

confidence: 99%

“…(See also the reheating era baryogenesis [3,5,6], and non-thermal leptogenesis [7][8][9].) In these scenarios, the right-handed neutrinos are not necessary, and thus the effective theory to describe the phenomena is the same as the one for the low energy experiments, such as the neutrino oscillation experiments as well as the neutrinoless double beta decays.…”

Section: Introductionmentioning

confidence: 99%

“…The key fact is that flavor oscillations of active neutrinos during the reheating era provide CP violation just as in the neutrino oscillation phenomena we observe today [3]. It was shown that only with adding the higher dimensional Majorana mass term, LLHH, to the renormalizable SM, the baryon asymmetry can be generated during the thermalization process [4].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Throwing away antimatter via neutrino oscillations during the reheating era

Eijima

Kitano

J. Cosmol. Astropart. Phys.

2020

Self Cite

The simplest possibility to explain the baryon asymmetry of the Universe is to assume that radiation is created asymmetrically between baryons and anti-baryons after the inflation. We propose a new mechanism of this kind where CP-violating flavor oscillations of left-handed leptons in the reheating era distribute the lepton asymmetries partially into the right-handed neutrinos while net asymmetry is not created. The asymmetry stored in the righthanded neutrinos is later washed out by the lepton number violating decays, and it ends up with the net lepton asymmetry in the Standard Model particles, which is converted into the baryon asymmetry by the sphaleron process. This scenario works for a range of masses of the right-handed neutrinos while no fine-tuning among the masses is required. The reheating temperature of the Universe can be as low as O(10) TeV if we assume that the decays of inflatons in the perturbative regime are responsible for the reheating. For the case of the reheating via the dissipation effects, the reheating temperature can be as low as O(100) GeV.

Relaxing the cosmological moduli problem by low-scale inflation

Takahashi

2019

J. High Energ. Phys.

We show that the cosmological abundance of string axions is much smaller than naive estimates if the Hubble scale of inflation, H inf , is sufficiently low (but can still be much higher than the axion masses) and if the inflation lasts sufficiently long. The reason is that the initial misalignment angles of the string axions follow the Bunch-Davies distribution peaked at the potential minima. As a result, the cosmological moduli problem induced by the string axions can be significantly relaxed by low-scale inflation, and astrophysical and cosmological bounds are satisfied over a wide range of the mass without any fine-tuning of the initial misalignment angles. Specifically, the axion with its decay constant f φ = 10 16 GeV satisfies the bounds over 10 −18 eV m φ 10 TeV for H inf 10 keV − 10 6 GeV. We also discuss cases with multiple axions and the QCD axion.