Measuring inflaton couplings via primordial gravitational waves

Barman, Basabendu; Ghoshal, Anish; Grza̧dkowski, Bohdan; Socha, Anna

doi:10.1007/jhep07(2023)231

Cited by 14 publications

(1 citation statement)

References 122 publications

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“…This approximation is justified by the quadratic character on the inflationary potential around its minimum and the Plancksuppressed character of the interactions induced by the non-minimal coupling to gravity. The former aspects constitute, in fact, a remarkable difference from scenarios involving higher monomial potentials, viz., V (ϕ) ∝ ϕ k , where, despite what is usually assumed in the literature [29][30][31][32], non-perturbative effects cannot be generically ignored, leading almost universally to a radiation-like equation-of-state parameter [18,19,22,[108][109][110] in clear contrast to the value w = (k − 2)/(k + 2) obtained in the homogeneous approximation.…”

Section: Heating With a Linear Non-minimal Couplingmentioning

confidence: 99%

Rescuing gravitational-reheating in chaotic inflation

Barman,

Bernal,

Rubio

2024

J. Cosmol. Astropart. Phys.

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We show, within the single-field inflationary paradigm, that a linear non-minimal interaction ξ M P ϕ R between the inflaton field ϕ and the Ricci scalar R can result in successful inflation that concludes with an efficient heating of the Universe via perturbative decays of the inflaton, aided entirely by gravity. Considering the inflaton field to oscillate in a quadratic potential, we find that 𝒪(10-1) ≲ 𝒪 ≲ 𝒪(102) is required to satisfy the observational bounds from Cosmic Microwave Background (CMB) and Big Bang Nucleosynthesis (BBN). Interestingly, the upper bound on the non-minimal coupling guarantees a tensor-to-scalar ratio r ≳ 10-4, within the range of current and future planned experiments. We also discuss implications of dark matter production, along with the potential generation of the matter-antimatter asymmetry resulting from inflaton decay, through the same gravity portal.

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Section: Heating With a Linear Non-minimal Couplingmentioning

confidence: 99%

Rescuing gravitational-reheating in chaotic inflation

Barman,

Bernal,

Rubio

2024

J. Cosmol. Astropart. Phys.

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Axion-like particle (ALP) portal freeze-in dark matter confronting ALP search experiments

Ghosh,

Ghoshal,

Jeesun

2024

J. High Energ. Phys.

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The relic density of Dark Matter (DM) in the freeze-in scenario is highly dependent on the evolution history of the universe and changes significantly in a non-standard (NS) cosmological framework prior to Big Bang Nucleosynthesis (BBN). In this scenario, an additional species dominates the energy budget of the universe at early times (before BBN), resulting in a larger cosmological expansion rate at a given temperature compared to the standard radiation-dominated (RD) universe. To investigate the production of DM in the freeze-in scenario, we consider both standard RD and NS cosmological picture before BBN and perform a comparative analysis. We extend the Standard Model (SM) particle content with a SM singlet DM particle χ and an axion-like particle (ALP) a. The interactions between ALP, SM particles, and DM are generated by higher dimensional effective operators. This setup allows the production of DM χ from SM bath through the mediation of ALP, via ALP-portal processes. These interactions involve non-renormalizable operators, leading to ultraviolet (UV) freeze-in, which depends on the reheating temperature (TRH) of the early universe. In the NS cosmological scenario, the faster expansion rate suppresses the DM production processes, allowing for enhanced effective couplings between the visible and dark sectors to satisfy the observed DM abundance compared to RD scenario. This improved coupling increases the detection prospects for freeze-in DM via the ALP-portal, which is otherwise challenging to detect in RD universe due to small couplings involved. Using an effective field theory set-up, we show that various ALP searches such as in FASER, DUNE, and SHiP, etc. will be able to probe significant parameter space depending on the different model parameters.

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Probing flavor violation and baryogenesis via primordial gravitational waves

Borboruah,

Ghoshal,

Ipek

2024

J. High Energ. Phys.

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We show that observations of primordial gravitational waves of inflationary origin can shed light into the scale of flavor violation in a flavon model which also explains the mass hierarchy of fermions. The energy density stored in oscillations of the flavon field around the minimum of its potential redshifts as matter and is expected to dominate over radiation in the early universe. At the same time, the evolution of primordial gravitational waves acts as bookkeeping to understand the expansion history of the universe. Importantly, the gravitational wave spectrum is different if there is an early flavon dominated era compared to radiation domination expected from a standard cosmological model and this spectrum gets damped by the entropy released in flavon decays, determined by the mass of the flavon field mS and new scale of flavor violation ΛFV. We derive analytical expressions of the frequency above which the spectrum is damped, as-well-as the amount of damping, in terms of mS and ΛFV. We show that the damping of the gravitational wave spectrum would be detectable at BBO, DECIGO, U-DECIGO, μ−ARES, LISA, CE and ET detectors for ΛFV = 105−10 GeV and mS = $$ \mathcal{O}\left(\textrm{TeV}\right) $$ O TeV . Furthermore, the flavon decays can source the baryon asymmetry of the universe. We identify the mS – ΛFV parameter space where the observed baryon asymmetry η ~ 10−10 is produced and can be tested by gravitational wave detectors like LISA and ET. We also discuss our results in the context of the recently measured stochastic gravitational background signals by NANOGrav.

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Measuring inflaton couplings via primordial gravitational waves

Cited by 14 publications

References 122 publications

Rescuing gravitational-reheating in chaotic inflation

Rescuing gravitational-reheating in chaotic inflation

Axion-like particle (ALP) portal freeze-in dark matter confronting ALP search experiments

Probing flavor violation and baryogenesis via primordial gravitational waves

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