Abstract: The CPT symmetry, which combines Charge Conjugation, Parity, and Time Reversal, is a cornerstone of our model-building method, and its probable violation will endanger the most extended tool we presently utilize to explain physics, namely local relativistic quantum fields. However, the kaon system's conservation constraints appear to be rather severe. We will show in this paper that neutrino oscillation experiments can enhance this limit by many orders of magnitude, making them an excellent instrument for investigating the basis of our understanding of Nature. As a result, verifying CPT invariance does not evaluate a specific model, but rather the entire paradigm. Therefore, as the CPT's status in the neutrino sector, linked or not to Lorentz invariance violation, will be assessed at an unprecedented level by current and future long baseline experiments, distinguishing it from comparable experimental fingerprints coming from non-standard interactions is critical. Whether the entire paradigm or simply the conventional model of neutrinos is at jeopardy is significantly dependent on this.

Abstract: We investigate the potential impact of neutrino quantum decoherence on the precision measurements of standard neutrino oscillation parameters in the DUNE and T2HK experiments. We show that the measurement of delta(CP), sin(2) theta(13) and sin(2) theta(23) is stronger effected in DUNE than in T2HK. On the other hand, DUNE would have a better sensitivity than T2HK to observe decoherence effects. By performing a combined analysis of DUNE and T2HK we show that a robust measurement of standard parameters would be possible, which is not guaranteed with DUNE data alone.

Abstract: We consider the possibility that the cosmic neutrino background might have a nonthermal spectrum, and investigate its effect on cosmological parameters relative to standard A-cold dark matter (ACDM) cosmology. As a specific model, we consider a thermal y- distortion, which alters the distribution function of the neutrino background by depleting the population of low-energy neutrinos and enhancing the highenergy tail. We constrain the thermal y- parameter of the cosmic neutrino background using cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) measurements, and place a 95%-confidence upper bound of y <= 0.043. The y- parameter increases the number of effective relativistic degrees of freedom, reducing the sound horizon radius and increasing the best-fit value for the Hubble constant H 0 . We obtain an upper bound on the Hubble constant of H 0 = 71.12 km/s/Mpc at 95% confidence, substantially reducing the tension between CMB/BAO constraints and direct measurement of the expansion rate from type-Ia supernovae. Including a spectral distortion also allows for a higher value of the spectral index of scalar fluctuations, with a best-fit of n S = 0.9720 +/- 0.0063, and a 95%-confidence upper bound of n S <= 0.9842.

Abstract: The details of the minimal cosmological standard model (MCSM) proposed in [The minimal cosmological standard model, arXiv:2403.05390.] are discussed. The model is based on the scalesymmetry and the global Peccei-Quinn (PQ) symmetry with a key assumption that the latter is broken only in the gravity sector in a scale-invariant manner. We show that the model provides a quite simple unified framework for the unknown history of the Universe from inflation to the epoch of big-bang nucleosynthesis, simultaneously addressing key puzzles of high energy theory and cosmology: (i) the origin of scales, (ii) primordial inflation, (iii) matter-antimatter asymmetry, (iv) tiny neutrino masses, (v) dark matter, and (vi) the strong CP-problem. Scale symmetry can be exact, and the Planck scale is dynamically generated. The presence of Gauss-Bonnet term may safely retain dangerous nonperturbative symmetry-breaking effects negligible, allowing a large-field trans-Planckian inflation along the PQ-field. Isocurvature perturbations of axi-Majorons are suppressed. A sizable amount of PQ-number asymmetry is generated at the end of inflation, and conserved afterward. Domain wall problem is absent due to the nonrestoration of the symmetry and the nonzero PQ-number asymmetry. Baryogenesis can be realized by either the transfer of the PQ-number asymmetry through the seesaw sector, or by resonant leptogenesis. Dark matter is purely cold axi-Majorons from the misalignment contribution with the symmetry-breaking scale of O(1012) GeV. Hot axi-Majorons from the decay of the inflaton become a natural source for a sizable amount of dark radiation. Inflationary gravitational waves have information about the mass parameters of the lightest left-handed and right-handed neutrinos, thanks to the presence of an early matterdomination era driven by the long-lived lightest right-handed neutrino species.

Abstract: We propose a novel minimal scenario which simultaneously addresses the following theoretical/cosmological/phenomenological puzzles: (i) the origin of scales, (ii) primordial inflation, (iii) matter-antimatter asymmetry, (iv) tiny neutrino masses, (v) dark matter, and (vi) the strong CP-problem. Exact scale-symmetry was assumed. A global U(1)PQ-symmetry was also assumed but only in the matter sector. The novelty of the scenario is the introduction of explicit U(1)PQ-breaking terms with field-dependent coefficients in the gravity sector. Such a term does not disturb the axion solution whereas naturally realizes an axi-majoron hybrid inflation which allows a natural realization of Affleck-Dine mechanism for generating Peccei-Quinn number asymmetry. The asymmetry can be transferred to the visible sector via the right-handed neutrino portal through non-thermal decay and thermal processes, even without the presence of a CP-violating phase in the matter sector. Dark matter and dark radiation are obtained by cold and hot components of axi-majorons, respectively.