Sergei G. Rubin

Cosmological pattern of microphysics in the inflationary universe

1. Principles of Cosmoparticle Physics.- 2. Basis of Inflation.- 3. Quantum Fluctuations during Inflation.- 4. Strong Primordial Inhomogeneities and Galaxy Formation.- 5. Baryon Asymmetrical Universe with Antimatter Regions.- 6. Antimatter in the Modern Universe.- 7. Astronomy of Ultra High Energy Cosmic Rays.- 8. High Density Regions from First-order Phase Transitions.- 9. Fine-Tuning of Microphysical Parameters in the Universe.- 10. Inflation: Additional Resources.- Epilogue.- References.

Possible origin of antimatter regions in the baryon dominated universe

We discuss the evolution of U(1) symmetric scalar field at the inflation epoch with a pseudo Nambu-Goldstone tilt revealing after the end of exponential expansion of the Universe. The U(1) symmetry is supposed to be associated with baryon charge. It is shown that quantum fluctuations lead in natural way to baryon dominated Universe with antibaryon excess regions. The range of parameters is calculated at which the fraction of Universe occupied by antimatter and the size of antimatter regions satisfy the observational constraints, survive to the modern time and lead to effects, accessible to experimental search for antimatter.

The universe formation by space reduction cascades with random initial parameters

In this paper we discuss the creation of our universe using the idea of extra dimensions. The initial, multidimensional Lagrangian contains only metric tensor. We have found many sets of the numerical values of the Lagrangian parameters corresponding to the observed low-energy physics of our Universe. Different initial parameters can lead to the same values of fundamental constants by the appropriate choice of a dimensional reduction cascade. This result diminishes the significance of the search for the ‘unique’ initial Lagrangian. We also have obtained a large number of low-energy vacua, which is known as ‘landscape’ in the string theory.

Inflation: Additional Resources

Up to now our consideration was performed in the framework of chaotic inflation. We revealed that scalar field(s) connected with gravity gives rise to a very interesting and important period of the evolution of our Universe. A lot of observational data can find new nontrivial explanation in this framework. In addition, new phenomena are predicted, some of them having been discussed in this book.

Astronomy of Ultra High Energy Cosmic Rays

Ultra High Energy Cosmic Rays (UHECR) is the observed effect of superhigh energy physics in the modern Universe, which naturally puts together particle physics and cosmology in the analysis of their possible origin and effects. Even for known particles and interactions UHECR correspond to the energy range at which their properties were not studied experimentally. Particle theory predicts a wide variety of new phenomena in this energy range. One should take into account the possibility of these phenomena in the analysis of the mechanisms of UHECR origin, propagation and detection. Moreover, such phenomena are unavoidable in the modern Big Bang cosmology, based on inflationary models with baryosynthesis and (multicomponent?) nonharyonic dark matter. The physics of inflation and baryosynthesis, as well as dark matter/energy content implies new particles, fields and mechanisms, predicted in the hidden sector of particle theory. Such particles, fields and mechanisms may play an important role in the problem of UHECR. It makes new physics a necessary component of the analysis of UHECR data.

Baryon Asymmetrical Universe with Antimatter Regions

The statement that our Universe is baryon asymmetrical is a quite firmly established observational fact, being one of the cornerstones of contemporary cosmology (sec review in [3]). Indeed, if large regions of matter and antimatter co-exist now, the annihilation would take place at the borders of these regions being the source of enormous gamma radiation that is not observed. If the typical size of such a domain structure was small enough, domains would be annihilated completely. Then the energy released by the annihilation would result, depending on the period of annihilation, in diffuse γ —ray background, in distortions of the spectrum of the cosmic microwave radiation, or in peculiarities of light element abundance, neither of which is observed (sec [313] for review). Recent analysis of this problem [272] for a baryon symmetric Universe claimed that the sire of domain regions should exceed 1000 Mpc, being comparable with the modern cosmological horizon. It therefore seems more plausible that the Universe is fundamentally matter antimatter asymmetric.

Fine-Tuning of Microphysical Parameters in the Universe

The general way of development of physics is supported by a whole number of observational and experimental data. On the other hand, some phenomena which we expected to be discovered for a long time, are still only hypotheses. Other data, being very impressive, are yet not explained. As an example, it is worth mentioning the existence of dark matter and dark energy, of superhigh energy particles in cosmic rays and ‘bursts’ an almost instantaneous energy explosion with energy release of order l053 erg. These astrophysical data specify presence of the new phenomena, which should be comprehended.

Quantum Fluctuations during Inflation

Quantum field theory teaches us that a classical motion of a system is disturbed by quantum fluctuations. In the Minkowski space their role is rather weak because quantum corrections are proportional to Planck constant h. In addition, according to Heisenberg’s uncertainty principle, the larger the fluctuation, the smaller time it exists. A much more interesting picture was discovered in the inflationary stage. As it was shown in Chapter 2, this stage may be approximated by de Sitter space. The most important property of inflation is that any inhomogencity grows in space, going far beyond the horizon size. The fluctuations are also the specific sort of inhomogeneities. It seems reasonable that their destiny differs from the destiny of the fluctuations in Minkowski space. In de Sitter space, quantum fluctuations do not die out. On the contrary, their size in space increases exponentially as compared with the size of horizon and they contribute to classical constituent of the field. This process reminds us of a pair creation in strong fields. The energy is conserved due to work produced by the field. In our case this field is evidently a gravitational one. In this chapter we consider shortly important results on quantum fluctuations during the inflationary stage that are supported by modern observations.

Antimatter in the Modern Universe

It was shown in [85], [276], [83] and discussed in the previous chapter that the existence of antimatter domains in the baryon-dominated Universe is a profound signature for the origin and evolution of primordial baryon matter inhomogeneity. Depending on its parameters the mechanism of inhomogeneons baryosynthesis can lead to both high and low antibaryon density domains. According to [85] high density domains can evolve into antimatter stellar objects so that a globular cluster of antimatter stars can exist in our Galaxy, that may be tested in the cosmic searches for antimatter planned for the near future. Such searches involve both direct search for pieces of antimatter — for antinuclei or antimeteorites, or use indirect probes by gamma radiation that may be originated from antimatter annihilation.

Basis of Inflation

Inflationary phenomena were discovered in seventies years of the previous century but the true triumph of inflation came in eighties, Its success in the explanation of the observable Universe was so impressive that the majority of scientists had no doubts on its correctness, at least as the basic principle, Unfortunately (or maybe, on the contrary, fortunately) the mechanism of inflation may be put into practice by a variety of ways. It led to overproduction of the inflationary models, a number of which increase constantly. Below we discuss the properties of inflationary scenario on the basis of chaotic inflation. Some other models are considered in Chapter 10 to give imagination on the beauty and rich possibilities of the inflationary paradigm.