Browsing by Author "Aqsa Saleem"

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    Gravitational Baryogenesis within f (R; T ; Q) Gravity using Isotropic and Anisotropic Universe Models
    (Library Information Services, CUI Lahore, 2022) Aqsa Saleem; SP21-RMT-032; Dr. Rabia Saleem
    This thesis is concerned with two parts: The main objective of the first part is to analyze the baryogenesis in the framework of f (R; T; Q) gravity under an isotropic universe model, where R and T represent the Ricci scalar and the trace of the energy-momentum tensor (EMT), respectively, and Q R T . We ex- plore baryogenesis with non-minimal (NM) coupling between R and T . For this, we use dust and stiff-type fluids with power-law and de-sitter-type solu- tions of the scale factor. In the end, we compute the baryon asymmetry factor (BAF) for some recently proposed models of this gravity, and then we com- pare our findings with observational limits on BAF. We also discuss generalized gravitational baryogenesis in detail.In the second part, we use different types of dark energy (DE) entropies such as Barrow entropy (BE), Sharma-Mittal entropy (SME), and generalized con- struction of these entropies to discuss the issue of baryogenesis. We find con- straints on the entropies parameters to get the physical results of BAF com- pared to the standard observational value. To derive the modified Friedmann field equations (FFEs), we use entropies and the first law of thermodynamics. Thus, even in the presence of the typical interaction between the Ricci scalar and baryon current, this results in non-trivial modifications to the mass density and pressure content of the universe, which provide a viable mechanism allowing for baryogenesis. Finally, we show that even in the radiation-dominant era BAF is non-zero.