This book is written from the viewpoint of a deep connection between cosmology and particle physics. It presents the results and ideas on both the homogeneous and isotropic Universe at the hot stage ...of its evolution and in later stages. The main chapters describe in a systematic and pedagogical way established facts and concepts on the early and the present Universe. The comprehensive treatment, hence, serves as a modern introduction to this rapidly developing field of science. To help in reading the chapters without having to constantly consult other texts, essential materials from General Relativity and the theory of elementary particles are collected in the appendices. Various hypotheses dealing with unsolved problems of cosmology, and often alternative to each other, are discussed at a more advanced level. These concern dark matter, dark energy, matter-antimatter asymmetry, etc.
This book accompanies another book by the same authors, Introduction to the Theory of the Early Universe: Hot Big Bang Theory and presents the theory of the evolution of density perturbations and ...relic gravity waves, theory of cosmological inflation and post-inflationary reheating. Written in a pedagogical style, the main chapters give a detailed account of the established theory, with derivation of formulas. Being self-contained, it is a useful textbook for advanced undergraduate students and graduate students. Essential materials from General Relativity, theory of Gaussian random fields and quantum field theory are collected in the appendices. The more advanced topics are approached similarly in a pedagogical way. These parts may serve as a detailed introduction to current research.
An algorithm of channel joint equalization and demodulation of multicarrier signals with nonorthogonal frequency spacing (spectrally efficient frequency division multiplexing, SEFDM) is proposed. It ...is based on DFT (Discrete Fourier Transform) and BCJR (Bahl, Cocke, Jelinek and Raviv) algorithm adapted to work with frequency samples of received signal. The performance of proposed receiver is comparable with performance of classic OFDM-signal receivers.
We investigate the prospects of the Spectrum-Roentgen-Gamma (SRG) mission in search for the keV-scale mass sterile neutrino dark matter radiatively decaying into active neutrinos and photons. The ...ongoing all-sky x-ray survey of the SRG space observatory with data acquired by the ART-XC and eROSITA telescopes can provide a possibility to fully explore the resonant production mechanism of the dark matter sterile neutrino, which exploits the lepton asymmetry in the primordial plasma consistent with cosmological limits from the big bang nucleosynthesis. In particular, it is shown that at the end of the four year all-sky survey, the sensitivity of the eROSITA telescope near the 3.5 keV line signal reported earlier can be comparable to that of the XMM-Newton with all collected data, which will allow one to carry out another independent study of the possible sterile neutrino decay signal in this area. In the energy range below ≈2.4 keV, the expected constraints on the model parameters can be significantly stronger than those obtained with the XMM-Newton. From the ART-XC data, in the energy range approximately from 5 to 20 keV, it can be possible to get more stringent constraints than those obtained with NuSTAR so far. We conclude that the SRG mission has a very high potential in testing the sterile neutrino dark matter hypothesis.
For supersymmetric extensions of the Standard Model with light sgoldstinos-scalar and pseudoscalar superpartners of goldstinos-we estimate the signal rate anticipated at the recently proposed fixed ...target experiment SHiP utilizing a CERN Super Proton Synchrotron beam of 400 GeV protons. We also place new limits on the model parameters from a similar analysis of the published results of the CHARM experiment.
NEWSdm Nuclear Emulsions for WIMP (weakly interacting massive particles) Search—directional measurement is a new international experiment in which a photoemulsion target is used for a direct ...detection of dark-matter particles. In this experiment, the detection method is based on fixing the directions of trajectories of recoil nuclei originating from the elastic interaction of target nuclei with dark-matter particles from the galactic halo. This distinguishes NEWSdm from standard low-background experiments aimed at searches for dark-matter particles and based on an analysis of annual modulations of the number of detected events. The detector, which is simultaneously a target, is a block of nuclear emulsions that have a uniquely high spatial resolution owing to the reduction of the size of AgBr grains to about
nm. A resolution on this order of magnitude permits directional searches for dark-matter particles in cosmic space even at energies of recoil nuclei not higher than 30 keV.
Etching kinetics of swift heavy ions (SHI) tracks in olivine is investigated in frame of experimentally verified numerical approach. The model takes into account variation of induced chemical ...reactivity of the material around the whole ion trajectory with the nanometric accuracy. This enables a quantitative description of wet chemical etching of SHI tracks of different lengths and orientations towards to the sample surface. It is demonstrated that two different modes of etching, governed by diffusion of etchant molecules and by their reaction with the material must be observed in experiments using techniques with different resolution thresholds. Applicability limits of the optical microscopy for detection of heavy ion parameters by measuring of the lengthwise etching rates of the ion track are discussed.
We describe the formation of swift heavy ion tracks in polyethylene (PE) by combining the Monte Carlo code TREKIS, which models electronic excitation in nanometric proximity of the ion trajectory, ...with the molecular dynamics simulating a response of the atomic system to the excitation. The model predicts circular tracks in amorphous PE but elliptical ones in crystalline PE caused by preferential propagation of excitation along polymer chains during the cooling stage. The obtained track sizes and shapes agree well with the high-resolution transmission microscopy of tracks in PE with colorant. The velocity effect in PE is shown: the track parameters differ for ions with the same linear energy losses but different velocities.
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