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Publications related to Physical Cosmology (1,096)
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Preprint
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The main objective of this work is to reject-geometry by presenting a novel comprehensive explanation for the gravitational force field. This novel approach can be thought of as the stronger version of the General Relativity. This work postulates that spacetime geometry is the direct reflection of the matter-energy content of the universe. It propo...
Article
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We study the cosmological impact of warm, dark-sector relic particles produced as Hawking radiation in a primordial-black-hole-dominated universe before big bang nucleosynthesis. If these dark-sector particles are stable, they would survive to the present day as Hawking relics and modify the growth of cosmological structure. We show that such relic...
Article
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The time evolution of primordial fluctuations conceals a wealth of insights into the high-energy physics at play during the earliest moments of our Universe, which is ultimately encoded in late-time spatial correlation functions. However, the conventional procedure to compute them is technically challenging, and a complete dictionary mapping the la...
Preprint
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This article offers an in-depth exploration of the relationship between consciousness and the cosmos, developing a cosmic ontology in which consciousness is not merely a biological emergence but constitutes an intrinsic dynamic of universal becoming. This approach is based on the idea that consciousness, far from being an isolated phenomenon, manif...
Preprint
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The concepts of black holes and dark holes have become central to modern theoretical physics, cosmology, and astrophysics. While the term "black hole" is well-defined within the framework of general relativity, the term "dark hole" has emerged in some areas of research to describe a potentially different class of astrophysical objects. This paper a...
Preprint
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This paper explores human-AI collaboration in scientific problem-solving through analogical reasoning, comparing the unconscious mind’s probabilistic exploration to AI models and the conscious mind’s step-by-step reasoning. Integrating unconscious thought theory and dual-process theory proposes frameworks in physics, cosmology, and free will. It di...
Article
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We analyse the impact of dark matter density spike around the Milky Way's supermassive black hole (SMBH), Sgr A*, in probing the Bino-dominated neutralino dark matter (DM) χ ~101⁰ within the MSSM, which typically produces relatively faint signals in the conventional DM halos. In particular, we explore the indirect search prospects of sub-TeV Bino-H...
Article
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This paper proposes two levels of preheating for the inflaton that is non-minimally coupled with gravity. The first level, later named by the quadratic regime, corresponds to the matter-dominated era and is responsible for draining the inflaton's energy density. The second level, which we will call the quartic regime, corresponds to the radiation-d...
Article
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We explore the cosmological and astrophysical implications of a realistic hybrid inflation model based on flipped SU(5). The model contains superheavy metastable cosmic strings arising from a waterfall field that encounters a limited number of e-foldings during the inflationary phase. In addition to the gravitational waves emitted by the metastable...
Article
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Sub-GeV dark matter (DM) particles produced via thermal freeze-out evade many of the strong constraints on heavier DM candidates but at the same time face a multitude of new constraints from laboratory experiments, astrophysical observations and cosmological data. In this work we combine all of these constraints in order to perform frequentist and...
Article
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The invisible decay of cold dark matter into a slightly lighter dark sector particle on cosmological time-scales has been proposed as a solution to the S 8 tension. In this work we discuss the possible embedding of this scenario within a particle physics framework, and we investigate its phenomenology. We identify a minimal dark matter decay setup...
Preprint
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In cosmological special relativity theory, we study Maxwell equations, electromagnetic wave equations and functions. In the cosmological special theory of relativity, we study energy-momentum relations, the Klein-Gordon equation and wave functions. If we solve the Klein-Gordon equation, we obtain the Yukawa potential in the cosmological inertial fr...
Article
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By coupling to both the Higgs and electroweak gauge sectors, an axion can generate the matter-antimatter asymmetry in the universe via electroweak baryogenesis when the axion decay constant lies within the range of approximately 10⁵ and 10⁷ GeV, corresponding to axion masses between the MeV and GeV scales. In this work, we explore the intriguing po...
Article
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Axion-like degrees of freedom generally interact with fermions through a shift symmetric coupling. As a consequence, a time-dependent axion will lead to the generation of fermions by amplifying their vacuum fluctuations. We provide the formulae that allow one to determine the spectra of produced fermions in a generic Friedmann-Lemaître-Robertson-Wa...
Preprint
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The use of extra dimensions has been used in physics for decades, and here we show its usefulness (with two extra time dimensions specifically) to modelling the stock market more accurately, as well as in the pricing of generalized exotic options. These extra 'time motions' can be used to include volatile interest rates, volatile volatility, random...
Preprint
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We perform the Becchi-Rouet-Stora-Tyutin (BRST) quantization of a (0 + 1)-dimensional non-interacting cosmological Friedmann-Robertson-Walker (FRW) model. This quantization leverages the classical infinitesimal and continuous reparameterization symmetry transformations of the system. To derive the nilpotent reparameterization invariant (anti-)BRST...
Article
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This article introduces the Quantum Matrix Hypothesis, a theoretical framework that postulates the existence of a nonlinear, universal information matrix as the foundational medium underpinning quantum mechanics and space-time. Unlike traditional quantum fields, which operate within the confines of space-time, the quantum matrix exists beyond these...
Article
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Screening mechanisms are a natural method for suppressing long-range forces in scalar-tensor theories as they link the local background density to their strength. Focusing on Brans-Dicke theories, those including a non-minimal coupling between a scalar degree of freedom and the Ricci scalar, we study the origin of these screening mechanisms from a...
Conference Paper
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Calculating the vacuum energy density in quantum field theory gives a value that exceeds the observed value by 10^122 times, and many proposed approaches have not solved this problem and calculated its real value. However, the application of the microscopic theory of superconductivity to the description of the physical vacuum on the Planck scale fo...
Preprint
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Dark matter, constituting approximately 27% of the universe's mass-energy budget, remains one of the most enigmatic components in cosmology. While its gravitational effects are undeniable, its nature, distribution, and limits pose significant challenges to theoretical and observational astrophysics. This paper explores the boundaries of dark matter...
Article
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We study the reheating and non-thermal leptogenesis in the case of a vector inflaton. We concentrate on particle production during the phase of oscillating background, especially gravitational production induced by the presence of non-minimal coupling imposed by an isotropic and homogeneous Universe. Including processes involving the exchange of gr...
Article
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High-Frequency Gravitational Waves (HFGWs) constitute a unique window on the early Universe as well as exotic astrophysical objects. While the current gravitational wave experiments are more dedicated to the low frequency regime, the graviton conversion into photons in a strong magnetic field constitutes a powerful tool to probe HFGWs. In this pape...
Article
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Multiple fields can become dynamical during the inflationary epoch. We consider an example where a light field acquires isocurvature fluctuations during inflation and contributes to the dark matter abundance at late times. Interactions between the light field and the adiabatic sector contribute to mixed adiabatic-isocurvature non-Gaussianity (NG)....
Preprint
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The proton's extraordinary lifetime, far exceeding the age of the universe, poses profound questions about the stability of matter, the nature of physical laws, and their connection to the structure of the universe. In this paper, we explore the proton's stability through the lens of particle physics, cosmology, and quantum field theory, emphasizin...
Article
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Resumo: Este artigo trata de uma pesquisa do tipo Estado da Arte cujo objetivo foi identificar e analisar as dissertações e teses defendidas no período de 1972 a 2019, que usaram como referencial o autor Vigotski e que trataram de práticas pedagógicas sobre ensino de Física Moderna e Contemporânea para o Ensino Médio. Os trabalhos foram classificad...
Article
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The natural inflation model with a periodic cosine potential is ruled out by recent Planck 2018 data for the decay constant f ≲ 5.5 M Pl. If the Planck data is combined with the BICEP Keck array and BAO data, the model is excluded (at 2-σ) for all values of f. In this context, we revisit the model when the pseudoscalar inflation ϕ is coupled with a...
Article
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In a recent paper, the NANOGrav collaboration studied new physics explanations of the observed pulsar timing residuals consistent with a stochastic gravitational wave background (SGWB) [1], including cosmic strings in the Nambu-Goto (NG) approximation. Analysing one of current models for the loop distribution, it was found that the cosmic string mo...
Article
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We investigate the possibility of achieving post-inflationary reheating exclusively through the gravitational interaction in Starobinsky inflation, which itself assumes nothing but gravity. We consider the possibility that the reheating sector couples to gravity via a non-minimal coupling. Our analysis is performed both in a perturbative and in a n...
Article
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The existence of pseudo-Nambu-Goldstone boson (pNGB) fields is a common feature in many models beyond the Standard Model, characterized by their exclusive derivative couplings. This paper investigates a scenario where a pNGB is coupled to the inflaton field during the reheating phase of the early universe. We calculate the perturbative decay rate o...
Preprint
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The Riemann Hypothesis is one of the most profound and enigmatic problems in mathematics, sitting at the crossroads of number theory, complex analysis, and the mysteries of infinity. First proposed by Bernhard Riemann in 1859, this hypothesis asserts that all nontrivial zeros of the Riemann zeta function lie on the critical line where the real part...
Preprint
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This paper presents a comprehensive study on a new equivalence principle, leading to the derivation of generalized Maxwell and Dirac equations. By introducing novel field variables, extended symmetry considerations, and modified interaction terms, we demonstrate the profound implications of these equations in describing electromagnetic fields and q...
Article
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The concept of time has been a subject of intrigue and fascination for centuries. This scientific article aims to delve into the dual nature of time, highlighting its relations as a form of energy (postulation) and its connection as a dimension of space. Drawing from various scientific theories and empirical evidence, we provide a comprehensive exa...
Article
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Cosmic Microwave Background (CMB) photons can undergo resonant conversion into axions in the presence of magnetized plasma distributed inside non-linear large-scale structure (LSS). This process leads to axion-induced patchy screening: secondary temperature and polarization ani­sotropies with a characteristic non-blackbody frequency dependence that...
Article
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Cosmological observations allow to measure the abundance of light relics produced in the early Universe. Most studies focus on the thermal freeze-out scenario, yet light relics produced by freeze-in are generic for models in which new light degrees of freedom do not couple strongly enough to the Standard Model (SM) plasma to allow for full thermali...
Article
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Higgs Inflation via a metastable Standard Model Higgs Potential is possible if the effective Planck mass in the Jordan frame increases after inflation ends. Here we consider the predictions of this model independently of the dynamics responsible for the Planck mass transition. The classical predictions are the same as for conventional Higgs Inflati...
Preprint
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The Mathematical Field Hypothesis proposes a bold reimagining of mathematics—not merely as a descriptive language or abstract tool, but as a tangible, universal field that underpins reality itself. This hypothesis speculates that mathematics exists as an intrinsic field structure, influencing the behavior of particles, governing fundamental forces,...
Preprint
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The origin of life on Earth remains one of science’s greatest mysteries, and while traditional theories such as the primordial soup and hydrothermal vent models have provided valuable insights, they may not fully capture the complexity of life’s beginnings. Recent advances in physics, chemistry, and cosmology present intriguing new possibilities, s...
Article
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In this paper, we explore an extension of the classical non-standard cosmological scenario in which the new field, ϕ, which interacts with the radiation component in the early universe, experiences dissipative processes in the form of a bulk viscosity. Assuming an interaction term given by Γ ϕ ρ ϕ , where Γ ϕ accounts for the decay rate of the fiel...
Article
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We quantitatively analyze a basic question: what is the stationary solution of the background plasma temperature profile around a black hole (BH)? One may naively expect that the temperature profile continuously decreases from the Hawking temperature at the surface of the BH towards an outer region. We show analytically and numerically that this is...
Article
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The minimal U(1) Lμ - Lτ gauge symmetry extended Standard Model (SM) is a well motivated framework that resolves the discrepancy between the theoretical prediction and experimental observation of muon anomalous magnetic moment. We envisage the possibility of identifying the beyond Standard Model Higgs of U(1) Lμ - Lτ sector, non-minimally coupled t...
Article
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Building on recently constructed inflationary vector dark matter production mechanisms as well as studies of magnetogenesis, we show that an inflationary dark Schwinger mechanism can generate the observed dark matter relic abundance for `dark electron' masses as light as ∼ 0.1 eV and as heavy as 10¹² GeV. The dark matter can interact very weakly vi...
Article
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If the inflaton is a heavy scalar field, it may equilibrate slower than some other degrees of freedom, e.g. non-Abelian gauge bosons. In this case, perturbations in the inflaton field and in a thermal plasma coexist from a given moment onwards. We derive a gauge-invariant set of three coupled equations governing the time evolution of such a system....
Article
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We develop a tool for the analysis of stochastic gravitational wave backgrounds from cosmological first-order phase transitions with LISA: we initiate a template databank for these signals, prototype their searches, and forecast their reconstruction. The templates encompass the gravitational wave signals sourced by bubble collisions, sound waves an...
Article
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Among the open problems in fundamental physics, few are as conceptually significant as the “measurement problem” in Quantum Mechanics. One of the proposed solutions to this problem is the Continuous Spontaneous Localization (CSL) model, which introduces a non-linear and stochastic modification of the Schrödinger equation. This model incorporates tw...
Article
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We propose new classes of inflation models based on the modular symmetry, where the modulus field τ serves as the inflaton. We establish a connection between modular inflation and modular stabilization, wherein the modulus field rolls towards a fixed point along the boundary of the fundamental domain. We find the modular symmetry strongly constrain...
Article
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We show that an ultralight primordial black hole (PBH) dominated phase makes blue-tilted inflationary gravitational waves (BGW) compatible with the recent detection of an nHz stochastic GW background by pulsar-timing arrays (PTAs), for high reheating temperatures. This PBH-dominated phase suppresses the BGW spectrum via entropy dilution, making it...
Preprint
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This paper addresses a problem that arises from the ontological commitments of Integrated Information Theory (IIT) 4.0, particularly its stance that only conscious entities truly exist. This position leads to the "origin of consciousness problem": if non-conscious entities do not truly exist, how could consciousness have evolved from non-conscious...
Article
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The description of dark matter as a pressure-less fluid and of dark energy as a cosmological constant, both minimally coupled to gravity, constitutes the basis of the concordance ΛCDM model. However, the concordance model is based on using equations of motion directly for the fluids with constraints placed on their sources, and lacks an underlying...
Article
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We examine how the existence of a population of primordial black holes (PBHs) influences cosmological gravitational particle production (CGPP) for spin-0 and spin-1 particles. In addition to the known effects of particle production and entropy dilution resulting from PBH evaporation, we find that the generation of dark matter (DM) through CGPP is p...
Article
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We propose a novel and comprehensive particle physics framework that addresses multiple cosmological tensions observed in recent measurements of the Hubble parameter, S 8, and Lyman-α forest data. Our model, termed `SIDR+z t ' (Self Interacting Dark Radiation with transition redshift), is based on an inelastic dark matter (IDM) scenario coupled wit...
Article
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In this paper, we examine the possibility that massive neutrinos are unstable due to their invisible decays ν i → ν j + ϕ, where ν i and ν j (for i, j = 1, 2, 3) are any two of neutrino mass eigenstates with masses m i > m i and ϕ is a massless Nambu-Goldstone boson, and explore the implications for the detection of cosmological relic neutrinos in...
Preprint
Full-text available
Calculation of the vacuum energy density in quantum field theory gives a value 10 ^122 times higher than the observed one, and many proposed approaches have not solved this problem and have not calculated its real value. However, the application of the microscopic theory of superconductivity to the description of the physical vacuum on the Planck s...
Article
Full-text available
Axions or axion-like particles (ALPs) are hypothetical particles predicted by beyond standard model theories, which make one of the dark matter candidates. These particles can convert into photons and vice-versa in the presence of a magnetic field, with a probability decided by its coupling strength gaγ . One of the ways to detect these particles i...
Article
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It was shown that the required high quality of the Peccei-Quinn (PQ) symmetry can be a natural outcome of the multiple QCD axions model. In the axiverse, a hypothetical mass mixing between the QCD axions and axion-like particles (ALPs) can occur, which leads to an interesting phenomenon called the level crossing. In this paper, we investigate this...
Article
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We explore the possibility of explaining the observed dark matter (DM) relic abundance, along with matter-antimatter asymmetry, entirely from the evaporation of primordial black holes (PBH) beyond the semi-classical approximation. We find that, depending on the timing of modification to the semi-classical approximation and the efficiency of the bac...
Article
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We explore the production of thermal dark matter (DM) candidates (WIMPs, SIMPs, ELDERs and Cannibals) during cosmic reheating. Assuming a general parametrization for the scaling of the inflaton energy density and the standard model (SM) temperature, we study the requirements for kinetic and chemical DM freeze-out in a model-independent way. For eac...
Article
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Models of stepped dark radiation have recently been found to have an important impact on the anisotropies of the cosmic microwave background, aiding in easing the Hubble tension. In this work, we study models with a sector of dark radiation with a step in its abundance, which thermalizes after big bang nucleosynthesis by mixing with the standard mo...
Article
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Very different processes characterize the decoupling of neutrinos to form the cosmic neutrino background (CνB) and the much later decoupling of photons from thermal equilibrium to form the cosmic microwave background (CMB). The CνB emerges from the fuzzy, energy-dependent neutrinosphere and encodes the physics operating in the early universe in the...
Article
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We present a systematic moment expansion for solving the semiclassical Boltzmann equations for electroweak baryogenesis. The expansion is developed in powers of adiabatic coordinate velocity, and it is used for computing the CP-violating seed asymmetry at the front of the phase transition wall, that sources the eventual baryon asymmetry of the univ...
Article
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We show how topologically stable superheavy magnetic monopoles and primordial black holes can be generated at observable levels by the waterfall field in hybrid inflation models based on grand unified theories. In SU(5) ×U(1) χ grand unification, the monopole mass is of order 4 × 10¹⁷ GeV, and it carries a single unit (2 π /e) of Dirac magnetic cha...
Article
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Use of natural unit is utmost important for research in high energy physics, particularly in the fields of ‘Elementary Particle Physics’, ‘Astro-particle Physics’ and `Physical Cosmology', because all the parameters turn out to be dimensionless. However, it is suggestive to work in a system of units, in which all the kinematical parameters may be e...
Article
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The prediction of a nearly scale-invariant spectrum of curvature and tensor fluctuations is among the main features of cosmic inflation. The current measurements of the primordial fluctuations in the cosmic microwave background (CMB) provide tight constraints on the amplitude of the scalar and tensor spectra, and the scalar tilt. However, the preci...
Article
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The recurrence of high order dimensionless ratios of the physical and cosmological parameters had for long fascinated scientists, Paul Dirac was one of the first to notice this, and after him this phenomena was named (Dirac large number hypothesis) , where he tried to explain such a recurrence in terms of varying gravitational constant Here, we wil...
Article
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We apply deep learning techniques to the late-time turbulent regime in a post-inflationary model where a real scalar inflaton field and the standard model Higgs doublet interact with renormalizable couplings between them. After inflation, the inflaton decays into the Higgs through a trilinear coupling and the Higgs field subsequently thermalizes wi...
Article
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We consider primordial nucleosynthesis in the presence of hypothetical quasi-stable doubly charged particles. Existence of X –– with macroscopic lifetimes will lead to the formation of its bound states with ⁴He and other light elements, significantly facilitating the subsequent formation of lithium nuclei. From observational constraints on maximum...
Article
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At the cosmological stage of radiation dominance, dark matter density spikes should form around primordial black holes. In the case when dark matter particles are able to annihilate, the density in the central regions of the spikes decreases due to the elimination of particles, which gives an upper bound on the central density. In this paper, the m...
Article
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The particle showers produced in the atmosphere due to the interactions of primary cosmic particles require a thorough understanding in the backdrop of searches for rare interactions. In this work, we made a comprehensive study of air shower simulations using various combinations of hadronic models and particle transport code of the CORSIKA package...
Article
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We investigate a novel reheating scenario proceeding through s-channel inflaton annihilation, mediated by a massive scalar. If the inflaton ϕ oscillates around the minimum of a monomial potential ∝ ϕ ⁿ, we reveal the emergence of resonance phenomena originating from the dynamic evolution of the inflaton mass for n>2. Consequently, a resonance appea...
Preprint
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Proposal Statement: It is possible to define Causality in so universally self-evident a manner as a pre-scientific Law that it can explain both (a) existent processes and (b) consciousness-based and language-based quasi-realities (information, images, ideas, knowledge, language, theories, truths, virtual worlds, etc.) pertinent to existents, with m...
Research Proposal
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Background: The concept of the universe's lifecycle, from its initial singularity to its potential collapse and rebirth, represents a profound area of cosmological inquiry. This theory explores the possibility that the universe undergoes infinite cycles of expansion and contraction, akin to stellar evolution and black hole formation. Objectives: Th...
Research Proposal
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Background: The concept of the universe's lifecycle, from its initial singularity to its potential collapse and rebirth, represents a profound area of cosmological inquiry. This theory explores the possibility that the universe undergoes infinite cycles of expansion and contraction, akin to stellar evolution and black hole formation. Objectives: Th...
Preprint
Full-text available
Calculating the vacuum energy density in quantum field theory gives a value that exceeds the observed value by 10^122 times, and many proposed approaches have not solved this problem and calculated its real value. However, the application of the microscopic theory of superconductivity to the description of the physical vacuum on the Planck scale fo...
Preprint
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Dr. Femi Oyewole explores the implications of black holes as the most computationally dense structures in the universe and their potential role in driving the acceleration of the universe’s expansion. This paper hypothesizes that merging black holes could lead to a state of maximum computational density within the ruliad. The study investigates two...
Article
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Gravitational lensing by massive objects along the line of sight to the source causes distortions to gravitational wave (GW) signals; such distortions may reveal information about fundamental physics, cosmology, and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observin...
Article
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The nature of dark matter is an unsolved cosmological problem and axions are one of the weakly interacting cold dark matter candidates. Axions or ALPs (Axion-like particles) are pseudo-scalar bosons predicted by beyond-standard model theories. The weak coupling of ALPs with photons leads to the conversion of CMB photons to ALPs in the presence of a...
Article
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Cosmic string loops are non-linear density fluctuations which form in the early universe and could play an important role in explaining many phenomena which are in tension with the standard ΛCDM model. Hence, the accretion process onto cosmic string loops should be studied in detail. Most previous works view loops as point masses and ignore the imp...
Article
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In this paper we show that it is possible to achieve successful hilltop inflation in which the inflaton is identified as the modulus field in a modular invariant theory. The dilaton plays a crucial role in shaping the potential. Modular invariant gaugino condensation provides the mechanism for the modulus stabilisation after inflation. The inflatio...
Article
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The Flatness Problem is a fine-tuning problem (defined as when a physical constant appears to fall within an arbitrarily precise range such that the current status of the Universe was able to be developed) in physical cosmology, related to the density of matter and energy in the universe. In this paper, I provide an overview of the problem, describ...
Article
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Sterile neutrinos (ν s s) are well-motivated and actively searched for hypothetical neutral particles that would mix with the Standard Model active neutrinos. They are considered prime warm dark matter (DM) candidates, typically when their mass is in the keV range, although they can also be hot or cold DM components. We discuss in detail the charac...
Article
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Cosmological first order phase transitions are typically associated with physics beyond the Standard Model, and thus of great theoretical and observational interest. Models of phase transitions where the energy is mostly converted to dark radiation can be constrained through limits on the dark radiation energy density (parameterized by ΔN eff). How...
Article
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Recently, the IceCube collaboration observed a neutrino excess in the direction of NGC 1068 with high statistical significance. This constitutes the second detection of an astrophysical neutrino point source after the discovery of a variable emission originating from the blazar TXS 0506+056. Neutrinos emitted by these sources traverse huge, well-de...
Article
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Even after dark matter chemically freezes out in the early universe, electromagnetic cascades from dark matter annihilation can still perturb the background photon spectrum when the universe temperature cools down to 0.5 keV. We revisit the CMB spectrum distortions caused by s-wave dark matter annihilation under the updated Planck data and the futu...
Article
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Starobinsky's R ² inflation manifests a best-fit scenario for the power spectrum of primordial density fluctuations. Observables derived from the slow-roll picture of the R ² model in the Einstein frame relies on the conformal transformation of the metric, which inevitably induces a unique exponential-type couplings of the rolling scalaron with all...
Article
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We consider an inflationary kinetic function with an integrable pole that is traversed during inflation. This scenario leads to enhanced spectra of primordial scalar inhomogeneities with detectable signals: formation of primordial black holes (that could explain Dark Matter) and scalar-induced gravitational waves (that could reproduce the recent Pu...
Article
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The Two-Higgs-Doublet-Standard Model-Axion-Seesaw-Higgs-Portal inflation (2hdSMASH) model consisting of two Higgs doublets, a Standard Model (SM) singlet complex scalar and three SM singlet right-handed neutrinos can embed axion dark matter, neutrino masses and address inflation. We report on an investigation of the inflationary aspects of 2hdSMASH...
Article
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Dark matter, if represented by a ℤ2-symmetric scalar field, can manifest as both particles and condensates. In this paper, we study the evolution of an oscillating homogeneous condensate of a ℤ2-symmetric scalar field in a thermal plasma in an FLRW universe. We focus on the perturbative regime where the oscillation amplitude is sufficiently small s...
Article
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Hot viscous plasmas unavoidably emit a gravitational wave background, similar to electromagnetic black body radiation. We study the contribution from hidden particles to the diffuse background emitted by the primordial plasma in the early universe. While this contribution can easily dominate over that from Standard Model particles, we find that bot...
Article
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We compute the power spectrum of super-horizon curvature perturbations generated during a late period of thermal inflation, taking into account fluctuation-dissipation effects resulting from the scalar flaton field's interactions with the ambient radiation bath. We find that, at the onset of thermal inflation, the flaton field may reach an equilibr...
Article
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The Hellings and Downs correlation curve describes the correlation of the timing residuals from pairs of pulsars as a function of their angular separation on the sky and is a smoking-gun signature for the detection of an isotropic stochastic background of gravitational waves. We show that it can be easily obtained from realizing that Lorentz transf...
Article
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We propose a new and compact realization of singlet Dirac dark matter within the WIMP framework. Our model replaces the standard Z 2 stabilizing symmetry with a Z 6, and uses spontaneous symmetry breaking to generate the dark matter mass, resulting in a much simplified scenario for Dirac dark matter. Concretely, we extend the Standard Model (SM) wi...
Article
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The Hubble diagram of quasars, as candidates to “standardizable” candles, has been used to measure the expansion history of the Universe at late times, up to very high redshifts (z ∼ 7). It has been shown that this history, as inferred from the quasar dataset, deviates at ≳ 3σ level from the concordance (ΛCDM) cosmology model preferred by the cosmi...
Article
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Topological defects are a universal concept across many disciplines, such as crystallography, liquid-crystalline physics, low-temperature physics, cosmology, and even biology. In nematic liquid crystals, topological defects called disclinations have been widely studied. For their three-dimensional (3D) dynamics, however, only recently have theoreti...
Article
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Axion-like particles with a coupling to non-Abelian gauge fields at finite temperature can experience dissipation due to sphaleron heating. This could play an important role for warm inflation or dynamical dark energy. We investigate to what degree the efficiency of this non-perturbative mechanism depends on the details of the underlying particle p...
Article
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We consider here natural inflation in the low energy (two-derivative) metric-affine theory containing only the minimal degrees of freedom in the inflationary sector, i.e. the massless graviton and the pseudo-Nambu-Goldstone boson (PNGB). This theory contains the Ricci-like and parity-odd Holst invariants together with non-minimal couplings between...
Article
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Dark matter freeze-in at stronger coupling is operative when the Standard Model (SM) bath temperature never exceeds the dark matter mass. An attractive feature of this scenario is that it can be probed by direct detection experiments as well as at the LHC. In this work, we show how the mechanism can be realized in a simple UV complete framework, em...
Article
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An epoch of matter domination in the early universe can enhance the primordial stochastic gravitational wave signal, potentially making it detectable to upcoming gravitational wave experiments. However, the resulting gravitational wave signal is quite sensitive to the end of the early matter-dominated epoch. If matter domination ends gradually, a c...
Article
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The theory of superfluid dark matter is characterized by self-interacting sub-eV particles that thermalize and condense to form a superfluid core in galaxies. Massive black holes at the center of galaxies, however, modify the dark matter distribution and result in a density enhancement in their vicinity known as dark matter spikes. The presence of...
Preprint
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In the quest for a comprehensive understanding of the universe, traditional physics has long sought to unify the fundamental forces and reconcile quantum mechanics with general relativity. The Spiritual Theory of Everything Model (STOEM) introduces a novel approach by integrating physical and spiritual dimensions, fractal geometry, and imaginary ti...
Article
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We estimate the equilibration rate of a nearly homogeneous Higgs field, displaced from its ground state during the onset of an electroweak phase transition. The computation is carried out with Hard Thermal Loop resummed perturbation theory, and a significant part of the result originates from Bose-enhanced t-channel 2 ↔ 2 scatterings. The expressio...
Article
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We explore various aspects concerning the role of vector bosons during the reheating process. Generally, reheating occurs during the period of oscillations of the inflaton condensate and the evolution of the radiation bath depends on the inflaton equation of state. For oscillations about a quadratic minimum, the equation of state parameter, w = p/ρ...