We argue that strong dynamics at the Planck scale can solve the cosmological moduli problem. We discuss its implications for inflation models, and find that a certain type of multi-field inflation model is required for this mechanism to work, since otherwise it would lead to the serious eta-problem. Combined with the inflaton-induced gravitino problem, we show that a chaotic inflation with a discrete symmetry naturally avoids both problems. Interestingly, the focus point supersymmetry is predicted when this mechanism is applied to the Polonyi model.
We show that the cosmological abundance of string axions is much smaller than naive estimates if the Hubble scale of inflation, $H_{\rm inf}$, 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 ra…
The physical history of the Universe is completed by including the quantum planckian and trans-planckian phase before Inflation in the Standard Model of the Universe in agreement with observations. A new quantum precursor phase appears beyond the Planck scale. We extend de Sitter universe to the quantum domain: classical-quantum de Sitter duality. As a result: The classical and quantum dual de Sitter Temperatures and Entropies are naturally included, and the different (classical, semiclassical, quantum planckian and super-planckian) de Sitter regimes characterized in a precise and unifying way…
We consider a quintessence model with Yukawa interaction between dark energy and dark matter and constrain this model by employing the recent cosmological data including the updated cosmic microwave background (CMB) measurements from Planck 2015, the weak gravitational lensing measurements from Kilo Degree Survey (KiDS) and redshift-space distortions. We find that an interaction in the dark sector is compatible with observations. The updated Planck data can significantly improve the constraints compared with the previous results from Planck 2013, while the KiDS data has less constraining power…
The recent Planck Legacy 2018 release has confirmed the presence of an enhanced lensing amplitude in CMB power spectra compared to that predicted in the standard $Λ$CDM model. A closed universe can provide a physical explanation for this effect, with the Planck CMB spectra now preferring a positive curvature at more than $99 \%$ C.L. Here we further investigate the evidence for a closed universe from Planck, showing that positive curvature naturally explains the anomalous lensing amplitude and demonstrating that it also removes a well-known tension within the Planck data set concerning the val…
Light moduli fields, gravitationally coupled scalar fields with no classical potential and which are expected to emerge as remnants from string theory compactification, are dangerous to cosmology in that 1. their late-time decays may disrupt successful Big Bang Nucleosynthesis (BBN), 2. they may decay into gravitino pairs which result in violation of BBN constraints or overproduction of lightest SUSY particles (LSPs, assumed to constitute at least a portion of the dark matter in the universe) and 3. they may decay directly into LSPs, resulting in gross DM overproduction. Together, these consti…
We show that string moduli have axion-philic nature owing to the model-insensitive derivative interactions arising from the Kaehler potential. The decay of a modulus into stringy axions occurs without suppression by the mass of final states. Interestingly, it turns out to hold in general not only for the scalar partner of the stringy axion but also for any other moduli. The decay into (pseudo) Nambu-Goldstone bosons (NGBs) also avoids such mass suppression if the modulus is lighter than or similar in mass to the scalar partner of the NGB. Such axion-philic nature makes string moduli a natural …
We use six tilted spatially-flat and untilted non-flat dark energy cosmological models in analyses of South Pole Telescope polarization (SPTpol) cosmic microwave background (CMB) data, alone and in combination with Planck 2015 CMB data and non-CMB data, namely, the Pantheon Type Ia supernovae apparent magnitudes, a collection of baryon acoustic oscillation data points, Hubble parameter measurements, and growth rates. Although the cosmological models that best-fit the Planck CMB and non-CMB data do not provide good fits to the SPTpol data, with the $χ^2$'s exceeding the expected value, given th…
Constraining neutrino mass and extra relativistic degrees of freedom in dynamical dark energy models using Planck 2015 data in combination with low-redshift cosmological probes: basic extensions to $Λ$CDM cosmology
