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This proceeding is an introduction to cosmological applications of the Lorentz gauge theory. It provides the ingredients for a unique, though yet tentative Λ CDM theory of cosmology. Emergence of spacetime is described by the spontaneous symmetry breaking called here the khronogenesis. Space is then associated with the field strength of the antiself-dual gauge potential, and gravity is associated with the self-dual field strength. In the cosmological setting, khronogenesis seems to predict inflation. It is shown that the Lorentz gauge theory allows the consistent description of spin currents which could have important roles in cosmological phenomenology. [ABSTRACT FROM AUTHOR]

The conversion of electromagnetic energy into magnetohydrodynamic energy occurs when the electric conductivity changes from negligible to finite values. This process is relevant during the epoch of reheating in the early universe at the end of inflation and before the emergence of the radiation-dominated era. We find that the conversion into kinetic and thermal energies is primarily the result of electric energy dissipation, while magnetic energy only plays a secondary role in this process. This means that since electric energy dominates over magnetic energy during inflation and reheating, significant amounts of electric energy can be converted into magnetohydrodynamic energy when conductivity emerges before the relevant length scales become stable. [ABSTRACT FROM AUTHOR]

Formulating a satisfactory quantum theory of gravity remains one of the most challenging tasks in theoretical physics. Some of the greatest minds in the field have employed considerable ingenuity to make progress. Among these attempts, several pioneering works of Thanu Padmanabhan are widely considered among the most insightful and unique. This article briefly reviews some of Padmanabhan's contributions to black hole physics, quantum cosmology, and quantum gravity. [ABSTRACT FROM AUTHOR]

We propose and study the new (generalized) E-type α-attractor models of inflation, in order to include formation of primordial black holes (PBHs). The inflaton potential has a near-inflection point where slow-roll conditions are violated, thus leading to large scalar perturbations collapsing to PBHs later. An ultra-slow roll (short) phase exists between two (longer) phases of slow-roll inflation. We numerically investigate the phases of inflation, derive the power spectrum of scalar perturbations and calculate the PBHs masses. For certain values of the parameters, the asteroid-size PBHs can be formed with the masses of 1017 ÷ 1019 g, beyond the Hawking evaporation limit and in agreement with current Cosmic Microwave Background observations. Those PBHs are a candidate for (part of) dark matter in the present Universe, while the gravitational waves induced by the PBHs formation may be detectable by the future space-based gravitational interferometers.

The conversion of electromagnetic energy into magnetohydrodynamic energy occurs when the electric conductivity changes from negligible to finite values. This process is relevant during the epoch of reheating in the early universe at the end of inflation and before the emergence of the radiation-dominated era. We find that the conversion into kinetic and thermal energies is primarily the result of electric energy dissipation, while magnetic energy only plays a secondary role in this process. This means that since electric energy dominates over magnetic energy during inflation and reheating, significant amounts of electric energy can be converted into magnetohydrodynamic energy when conductivity emerges before the relevant length scales become stable.

In 2007, Storti predicted that the value of the cosmic microwave background radiation (CMBR) temperature may be improved: from the particle data group (PDG) value of [T 0 = 2.725 ± 0.001 K] to [T 0 = 2.7254 K]. In 2011, the PDG revised their value of CMBR to [T 0 = 2.7255 ± 0.006 K]. In 2008, Storti predicted a ΛCDM Hubble constant of [H 0 = 67.0843 km/s/Mpc]. In the same year, the PDG published their value as being [H 0 = 73 ± 3 km/s/Mpc]. In 2013, the PDG published a revised value of [H 0] as being considerably lower [H 0 = 67.3 ± 1.2 km/s/Mpc]. These predictions and experimental confirmations, in particular the value of [H 0] being successfully predicted 5 years in advance of the Planck collaboration and without Planck satellite instrumentation, demonstrate the power of the technique applied. We utilize the same technique to calculate the present values of ΛCDM [H 0], [ΩΛ], [ΩM], [q], and [Λ]. Subsequently, we describe the complete history of the cosmos from the instant of the Big Bang to the present epoch, in complete agreement with the standard model of cosmology. Moreover, we explicitly demonstrate that the Hubble tension does not exist, in a companion publication to this research article. This is achieved by utilizing a single equation to calculate both values of Hubble constant associated with the Hubble tension.

We propose a modification of the Natural Inflation potential in such a way that the spontaneous symmetry breaking scale f can take values less than one (in Planck units). The proposed potential seems simple enough, however, its consequences are difficult to calculate analytically. Therefore, we illustrate the feasibility of the model by considering some numerical examples that easily satisfy the conditions imposed on the observables n s and r by the most recent observations, while at the same time maintaining the number of e-folds during the inflationary epoch within the expected range. [ABSTRACT FROM AUTHOR]

In a previous paper we have shown that superluminal particles are allowed by the general relativistic theory of gravity provided that the metric is locally Euclidean. Here we calculate the probability density function of a canonical ensemble of superluminal particles as function of temperature. This is done for both space-times invariant under the Lorentz symmetry group, and for space times invariant under an Euclidean symmetry group. Although only the Lorentzian metric is stable for normal matter density, an Euclidian metric can be created under special gravitational circumstances and persist in a limited region of space-time consisting of the very early universe, which is characterized by extremely high densities and temperatures. Superluminal particles also allow attaining thermodynamic equilibrium at a shorter duration and suggest a rapid expansion of the matter density.

Reheating is a process by which the inflaton's energy density transfers to conventional matter after cosmic inflation. Currently, there is no cosmic observational evidence to directly detect the reheating era, but it may impose additional constraints on inflationary models. Depending upon the model, e-folding number during reheating N re and the final reheating temperature T re , as well as its effective equation of state parameter ω re , may be directly linked to the inflation observables such as the scalar spectral index n s and the tensor-to-scalar ratio r. By restricting the values of the effective equation of state parameter observationally, one can derive more stringent limits on inflationary models than those obtained from other routes. In this paper, we are interested to consider the reheating era in an inflation model with a nonminimal derivative coupling of the scalar field to impose some severe constraints on the parameter space of the model in the light of Planck 2018 data. We study the reheating final temperature and e-folds number in terms of the scalar spectral index and ω re within a numerical analysis on the model's parameter space. To realize a viable range of the reheating equation of state parameter in this nonminimal derivative inflation model, we obtain some observationally acceptable subspaces in the N re − ω re phase plane. To this end, we consider some sort of polynomial potentials to obtain some constraints on the model's parameter space which corresponds to viable values of the scalar spectral index and tensor-to-scalar ratio released by Planck 2018 TT+TE+EE+LowE observational data. Finally, we compare the obtained constraints in this nonminimal set-up with those derived from a single, minimally coupled scalar field inflation model to reveal the physics of the reheating in the context of nonminimal derivative inflation model. [ABSTRACT FROM AUTHOR]

We study an extension of the unimodular cosmological inflation in the context of the non-minimal coupling of a generic scalar field with gravitational sector. We consider the non-minimal coupling of the scalar field and gravity as the only source of energy–momentum tensor in this setup. Without introducing new particles other than those already existing in electroweak theory, the generic scalar field's non-minimal coupling is responsible for the generation of the seeds of perturbations for structure formation and the observed Cosmic Microwave Background anisotropies in this scenario. We calculate inflation parameters in both the Jordan and Einstein frames, and then we study primordial spectral indices for slow-roll parameters in Einstein's frame at the first and second orders. The numerical results of this model are consistent with the Planck2018 and BICEP/Keck joint data sets in some subspaces of the model parameters space. By considering a sufficient amount of inflation, we estimate the strength of the non-minimal coupling parameter, ξ , to find appropriate new constraints on the values of this parameter. By comparing the numerical values of the inflation observables in two frames and also with observation, we comment on the issue of frames in this framework. [ABSTRACT FROM AUTHOR]

The current central experimental values of the parameters of the Standard Model give rise to a striking conclusion: metastability of the electroweak vacuum is favored over absolute stability. A metastable vacuum for the Higgs boson implies that it is possible, and in fact inevitable, that a vacuum decay takes place with catastrophic consequences for the Universe. The metastability of the Higgs vacuum is especially significant for cosmology, because there are many mechanisms that could have triggered the decay of the electroweak vacuum in the early Universe. We present a comprehensive review of the implications from Higgs vacuum metastability for cosmology along with a pedagogical discussion of the related theoretical topics, including renormalization group improvement, quantum field theory in curved spacetime and vacuum decay in field theory.

We consider the cosmological application of a (variant of) relatively newly proposed model1 unifying inflation, dark energy, dark matter, and the Higgs mechanism. The model was originally defined using additional non-Riemannian measures, but it can be reformulated into effective quintessential model unifying inflation, dark energy and dark matter. Here, we demonstrate numerically that it is capable of describing the entire evolution of the Universe in a seamless way, but this requires some revision of the model setup. The main reason is that there is a strong effective friction in the model, a feature which has been neglected in the pioneer work. This improves the model potential for proper description of the evolution of the Universe, because the friction ensures a finite time inflation with dynamically maintained low-value slow-roll parameters in the realistic scenarios. In addition, the model predicts the existence of a constant scalar field in late Universe. [ABSTRACT FROM AUTHOR]

We consider two noncanonical scalar fields [tachyon and Dirac-Born-Infeld (DBI)] with E-model type of the potential. We study cosmological inflation in these models to find possible -attractors. We show that similar to the canonical scalar field case, in both tachyon and DBI models there is a value of the scalar spectral index in small limit which is just a function of the e-folds number. However, the value of in DBI model is somewhat different from the other ones. We also compare the results with Planck2015 TT, TE, EE+lowP data. The reheating phase after inflation is studied in these models which gives some more constraints on the model parameters. [ABSTRACT FROM AUTHOR]

In the five-dimensional Einstein gravity, the simplest chaotic inflationary scenario on a 3-brane universe in a bulk space–time undergoes significant corrections, when the five-dimensional Planck scale is below about 1 0 17 GeV. As well as, the non-minimal coupling between the inflaton field and the induced scalar curvature on the Randall–Sundrum (RS) II brane leads to considerable modifications of the Friedmann constraint equation that affect on the inflationary dynamics of this braneworld model. In this paper, we revisit the main perturbation parameters in these two modified models with some sort of polynomial potentials in the reheating phase and perform a numerical analysis on the parameter space of the adopted models in confrontation with Planck 2018 data. There is no observational evidence to directly detect the reheating phase, but it could be parameterized in terms of the reheating final temperature T r e , a number of e-folds during reheating N r e and effective equation of state parameter during reheating, ω r e , which make a useful bridge between the reheating and inflationary eras. We obtain several significant constraints on the two inflationary braneworld models for some values of the parameter ω r e. The finite range of effective equation of state parameter in reheating era gives explicit constraints on the tensor-to-scalar ratio, r and the number of e-folds, N k. Therefore, in the next step we obtain some allowed ranges of the reheating equation of state parameter from acceptable subspaces in the N r e − ω r e phase plane in confrontation with Planck 2018 data. The comparison of these constraints for two different values of the brane tension as λ = 1 0 5 and λ = 1 0 9 in appropriate units, specifies the brane tension's role in reheating stage after minimal inflation on the brane. Then, we obtain such constraints from reheating phase in a non-minimal inflationary model on the RS II brane with induced gravity. Finally, we compare the reheating constraints in these two minimal and non-minimal models to shed more light on the physics of the reheating stage in the context of RS II braneworld with induced gravity. [ABSTRACT FROM AUTHOR]