Modified gravity models for inflation: In conformity with observations

Zhang, Xinyi; Chen, Che-Yu; Reyimuaji, Yakefu

doi:10.1103/physrevd.105.043514

Cited by 10 publications

(7 citation statements)

References 42 publications

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“…The solid line represents the feasible parameter space of the ENI model and we will choose m = 0.1 for the following discussion. In the ENI model, the parameter spaces of r and n s are consistent with the latest experimental data with 1σ error when N k varies in [55][56][57][58][59][60][61][62][63][64][65] and the decay constant is constrained to be less than 2M p . The r and n s of the NII model dependence curves under different e-folds numbers are shown as dotted lines of Fig.…”

Section: Cmb Constraintssupporting

confidence: 65%

“…Unfortunately, due to the limitation of the tensor-to-scalar ratio r , recent Planck + BICEP/Keck observations have ruled out the NI model [20,49]. Since then, a large number of modified NI models have appeared [50][51][52][53][54][55][56][57][58][59], in this paper, we will study the three modified single-filed NI models and consider the constraints of CMB and reheating for three models.…”

Section: (): V-volmentioning

confidence: 99%

“…The theoretical motivation for the NI model is clear and simple in form, but it is contradicted by observational data with more than 95% confidence, especially with the recently published experimental data of Planck + BICEP/Keck [20,49]. Based on this, many studies on modification of the NI model have been reported [50][51][52][53][54][55][56][57][58][59], which is expected to match the experimental data. This paper focuses on three modified single-field NI models, we derive the tensor-to-scalar ratio r and spectral index n s of the models, and investigate the reheating constraints on these models.…”

Section: Inflaton Potentialsmentioning

confidence: 99%

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Reheating constraints on modified single-field natural inflation models

et al. 2022

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In this paper, we discuss three modified single-field natural inflation models in detail, including Special generalized natural inflation model (SNI), extended natural inflation model (ENI) and natural inflation inspired model (NII). We derive the analytical expression of the tensor-to-scalar ratio r and the spectral index $$n_s$$ n s for those models. Then the reheating temperature $$T_{re}$$ T re and reheating duration $$N_{re}$$ N re are analytically derived. Moreover, considering the CMB constraints, the feasible space of the SNI model in $$(n_s, r)$$ ( n s , r ) plane is almost covered by that of the NII, which means the NII is more general than the SNI. In addition, there is no overlapping space between the ENI and the other two models in $$(n_s, r)$$ ( n s , r ) plane, which indicates that the ENI and the other two models exclude each other, and more accurate experiments can verify them. Furthermore, the reheating brings tighter constraints to the inflation models, but they still work for a different reheating universe. Considering the constraints of $$n_s$$ n s , r, $$N_k$$ N k and choosing $$T_{re}$$ T re near the electroweak energy scale, one can find that the decay constants of the three models have no overlapping area and the effective equations of state $$\omega _{re}$$ ω re should be within $$\frac{1}{4}\lesssim \omega _{re} \lesssim \frac{4}{5}$$ 1 4 ≲ ω re ≲ 4 5 for the three models.

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Section: Cmb Constraintssupporting

confidence: 65%

Section: (): V-volmentioning

confidence: 99%

Section: Inflaton Potentialsmentioning

confidence: 99%

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Reheating constraints on modified single-field natural inflation models

et al. 2022

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show abstract

“…The theoretical motivation for the NI model is clear and simple in form, but it is contradicted by observational data with more than 95% confidence, especially with the recently published experimental data of Planck+BICEP/Keck [20,49]. Based on this, many studies on modification of the NI model have been reported [50][51][52][53][54][55][56][57][58][59], which is expected to match the experimental data. This paper focuses on three modified single-field NI models, we derive the tensor-to-scalar ratio r and spectral index n s of the models, and investigate the reheating constraints on these models.…”

Section: Inflaton Potentialsmentioning

confidence: 99%

“…Unfortunately, due to the limitation of the tensor-to-scalar ratio r, recent Planck+BICEP/Keck observations have ruled out the NI model [20,49]. Since then, a large number of modified NI models have appeared [50][51][52][53][54][55][56][57][58][59], in this paper, we will study the three modified single-filed NI models and consider the constraints of CMB and reheating for three models.…”

Section: Introductionmentioning

confidence: 99%

Reheating constraints on modified single-field Natural Inflation models

Zhou,

Yu,

Pan

et al. 2022

Preprint

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In this paper, we discuss three modified single-field natural inflation models in detail, including Special generalized Natural Inflation model(SNI), Extended Natural Inflation model(ENI) and Natural Inflation inspired model(NII). We derive the analytical expression of the tensor-to-scalar ratio r and the spectral index ns for those models. Then the reheating temperature Tre and reheating duration Nre are analytically derived. Moreover, considering the CMB constraints, the feasible space of the SNI model in (ns, r) plane is almost covered by that of the NII, which means the NII is more general than the SNI. In addition, there is no overlapping space between the ENI and the other two models in (ns, r) plane, which indicates that the ENI and the other two models exclude each other, and more accurate experiments can verify them. Furthermore, the reheating brings tighter constraints to the inflation models, but they still work for a different reheating universe. Considering the constraints of ns, r, N k and choosing Tre near the electroweak energy scale, one can find that the decay constants of the three models have no overlapping area and the effective equations of state ωre should be within 1 4 ωre 4 5 for the three models.

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Towards a systematic study of non-thermal leptogenesis from inflaton decays

Zhang

2024

J. High Energ. Phys.

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This paper investigates non-thermal leptogenesis from inflaton decays in the minimal extension of the canonical type-I seesaw model, where a complex singlet scalar ϕ is introduced to generate the Majorana masses of right-handed neutrinos (RHNs) and to play the role of inflaton. First, we systematically study non-thermal leptogenesis with the least model dependence. We give a general classification of the parameter space and find four characteristic limits by carefully examining the interplay between inflaton decay into RHNs and the decay of RHNs into the standard-model particles. Three of the four limits are truly non-thermal, with a final efficiency larger than that of thermal leptogenesis. Two analytic estimates for these three limits are provided with working conditions to examine the validity. In particular, we find that the strongly non-thermal RHNs scenario occupies a large parameter space, including the oscillation-preferred K range, and works well for a relatively-low reheating temperature TRH ≥ 103 GeV, extending the lower bound on the RHN mass to 2 × 107 GeV. The lepton flavor effects are discussed. Second, we demonstrate that such a unified picture for inflation, neutrino masses, and baryon number asymmetry can be realized by either a Coleman-Weinberg potential (for the real part of ϕ) or a natural inflation potential (for the imaginary part of ϕ). The allowed parameter ranges for successful inflation and non-thermal leptogenesis are much more constrained than those without inflationary observations. We find that non-thermal leptogenesis from inflaton decay offers a testable framework for the early Universe. It can be further tested with upcoming cosmological and neutrino data. The model-independent investigation of non-thermal leptogenesis should be useful in exploring this direction.

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Modified gravity models for inflation: In conformity with observations

Cited by 10 publications

References 42 publications

Reheating constraints on modified single-field natural inflation models

Reheating constraints on modified single-field natural inflation models

Reheating constraints on modified single-field Natural Inflation models

Towards a systematic study of non-thermal leptogenesis from inflaton decays

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