Article
Physics, Particles & Fields
Zheng-Quan Cui, Yu-Xiao Liu
Summary: We investigate domain wall solutions of a real spinor field coupled with gravitation in five dimensions. A class of soliton configurations, acting as walls in five dimensions, is found with the support of a nonlinear spinor field. The study explores various solutions in the presence of nonconstant and constant curvature bulk spacetimes, showing that some of these solutions exhibit energy density distributions of domain walls for the spinor field. The stability of these spinor configurations is examined through linear perturbations and the localization of the zero mode of tensor perturbations is also discussed.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
T. Vinutha, K. Sri Kavya, K. Niharika
Summary: In this study, Bianchi type-III, V, and VI0 cosmological models are obtained through the extended theory of gravitation, with a focus on the role of parameter nu in explaining the evolution of the cosmos. The physical properties of the models, including accelerated expansion of the universe, were studied for various values of nu. The stability of the background solutions for all three models and their agreement with recent cosmological observations were also discussed.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Physics, Multidisciplinary
Franz G. Mertens, Bernardo Sanchez-Rey, Niurka R. Quintero
Summary: The research focuses on the dynamics of solitons in a one-dimensional nonlinear model based on the ABS model for Dirac spinors, exploring the behavior of solitons under different potentials and developing a collective coordinates theory to describe the moving solitons. The results of the CCs theory are confirmed through simulations of numerical solutions for solitons in the ABS spinor model.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Article
Physics, Multidisciplinary
Bijan Saha
Summary: Within the Bianchi type-II cosmological model, the role of a spinor field in the evolution of the Universe was studied. It was found that even in the absence of spinor field nonlinearity, the components of the spinor field's energy-momentum tensor along the principal axis were different. The presence of nontrivial non-diagonal components of the energy-momentum tensor imposed restrictions on both the geometry of space-time and the spinor field itself. The choice of f(x3) determined whether the space-time was locally rotationally symmetric or isotropic. Depending on this choice, positive lambda(1) with f f''not equal 0 resulted in an oscillatory mode of evolution, while f' not equal 0 led to an accelerated mode of expansion.
ROMANIAN JOURNAL OF PHYSICS
(2023)
Article
Astronomy & Astrophysics
Mark D. Roberts
Summary: The form and application of the Lanczos potential in Bianchi spacetime are examined. The Lanczos potential is identified in specific cases and then analyzed in a general case. Two coupled first order partial differential equations are derived, although a general solution has not yet been obtained. The focus is on applying this potential to cosmic energetics, specifically the study of gravitational and other field energies in the Universe.
Article
Physics, Mathematical
T. Vinutha, K. S. Kavya
Summary: This paper discusses the Bianchi type-III, V, and VI0 perfect fluid anisotropic cosmological models and explains their physical and geometrical properties through plots. The study finds that the background solutions of these models are stable and consistent with recent cosmological observations.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2022)
Article
Physics, Mathematical
Alcides Garat
Summary: In this article, we investigate the properties of Dirac spinors under Lorentz transformations, particularly in the context of reflection under local Abelian electromagnetic gauge transformations. By studying the sign change of the norm of orthogonal vectors, we identify appropriate quantum operators to describe the properties of discrete reflections in Minkowski spacetime, and present these results through two theorems.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Ashfaque H. Bokhari, Tahir Hussain, Jamshed Khan, Uzma Nasib
Summary: This paper investigates homothetic vector fields of Bianchi type I spacetimes using Rif tree approach. By transforming the homothetic symmetry equations to the reduced involutive form, the problem is split into cases and solved with restrictions on metric functions, resulting in new physically realistic metrics.
RESULTS IN PHYSICS
(2021)
Article
Astronomy & Astrophysics
M. Vijaya Santhi, Y. Sobhanbabu
Summary: The paper constructs interacting and non-interacting Tsallis holographic dark energy models in an anisotropic and homogeneous space time within the scalar tensor theory framework. The study focuses on obtaining well-known cosmological parameters and observing the support of recent observational data in the models' deceleration and equation of state parameters.
Article
Astronomy & Astrophysics
Suhail Khan, Maria Bukhari, Ali H. Alkhaldi, Akram Ali
Summary: This paper investigates Conformal Vector Fields (CVFs) of Bianchi type-I spacetimes by solving coupled Partial Differential Equations (PDEs) obtained from conformal Killing equations. Through direct integration techniques, the components of CVFs are explored, leading to a system of three integrability conditions. By solving these conditions, CVFs and conformal factors for unknown metric functions are obtained, revealing that Bianchi type-I spacetimes admit five or fifteen CVFs for specific choices of metric functions.
MODERN PHYSICS LETTERS A
(2021)
Article
Physics, Multidisciplinary
S. Ram, M. K. Verma
Summary: The paper discusses the evolution of a spatially homogeneous Bianchi type-VI0 cosmological model with anisotropic dark energy and massive scalar field in the framework of Lyre geometry. Exact solutions to Einstein's field equations are obtained using two supplementary conditions, showcasing physical and dynamical behaviors of the model. This model may hold significance in discussions about the early stages of the universe's evolution.
INDIAN JOURNAL OF PHYSICS
(2022)
Article
Astronomy & Astrophysics
Stefano Vignolo, Sante Carloni, Roberto Cianci, Fabrizio Esposito, Luca Fabbri
Summary: This study presents a tetrad-affine approach to investigate the coupling between f(Q) gravity and spinor fields of spin-1/2. Field equations and the conservation law of spin density are derived. The study focuses on Bianchi type-I cosmological models and provides a general procedure to solve the corresponding field equations. Analytical solutions are obtained in the case of f(Q) = alpha Q(n), showing isotropization at late times and the possibility of accelerated expansion depending on the exponent n.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Physics, Multidisciplinary
Y. Aditya, K. D. Raju, P. J. Ravindranath, D. R. K. Reddy
Summary: This article investigates a spatially homogeneous and anisotropic Bianchi type VI0 cosmological model with dark energy fluid and a massive scalar field in Einstein's theory of gravitation. The field equations are solved under specific conditions, leading to the evaluation of cosmological parameters and discussion of their dynamical aspects with reference to the accelerated expansion of the universe.
INDIAN JOURNAL OF PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Shabeela Malik, Fiaz Hussain, Taotao Sui, Arshad Ali, Sirajul Haq, Muhammad Ramzan
Summary: The research focuses on investigating conformal vector fields (CVFs) of Bianchi type I space-times in modified teleparallel gravity (MTG). By classifying the space-times, the study identified 31 distinct Bianchi type I classes in MTG, and found that only one class formulates conformally non-flat space-times that admit proper CVFs. In other cases, the space-times either become conformally flat or tend to admit homothetic vector fields or Killing vector fields. The dimension of CVFs for Bianchi type I space-times in MTG was found to be three, four, five, six, and fifteen, and the physical parameters associated with each solution were calculated. Moreover, the solutions were classified via energy conditions to discuss physically viable results.
RESULTS IN PHYSICS
(2023)
Article
Physics, Particles & Fields
Gilad Lifschytz, Milan Patra
Summary: We continue the program of bulk reconstruction for fermionic fields by reconstructing the Dirac fermion field in AdS(3) coupled to a Chern-Simons gauge field from the CFT. We demonstrate that the three conditions mentioned earlier, namely solving the equation of motion, satisfying expected transformation under modular flow, and a simple charge distribution at infinity, are all compatible and yield the same bulk operator. Additionally, we compute the bulk-boundary tree level three point function using the CFT construction.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Multidisciplinary
Bijan Saha
CANADIAN JOURNAL OF PHYSICS
(2018)
Article
Physics, Particles & Fields
Bijan Saha
PHYSICS OF PARTICLES AND NUCLEI
(2018)
Article
Physics, Multidisciplinary
Bijan Saha
EUROPEAN PHYSICAL JOURNAL PLUS
(2018)
Article
Physics, Multidisciplinary
Bijan Saha
EUROPEAN PHYSICAL JOURNAL PLUS
(2019)
Article
Physics, Nuclear
Bijan Saha
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2020)
Article
Physics, Multidisciplinary
K. A. Bronnikov, Yu. P. Rybakov, Bijan Saha
EUROPEAN PHYSICAL JOURNAL PLUS
(2020)
Article
Astronomy & Astrophysics
Bijan Saha
ASTROPHYSICS AND SPACE SCIENCE
(2020)
Article
Astronomy & Astrophysics
Bijan Saha
Article
Physics, Multidisciplinary
Bijan Saha
Summary: This paper studies the behavior of a nonlinear spinor field dependent on both time and radial coordinates within a static cylindrically symmetric space-time. It is revealed that the presence of nontrivial non-diagonal components of the energy-momentum tensor imposes restrictions on the metric functions and the spinor field. Comparatively, the case becomes more complicated than the one with time-independent spinor field.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Microbiology
Subhankar Mukherjee, Punyasloke Bhadury, Shravani Mitra, Sharmi Naha, Bijan Saha, Shanta Dutta, Sulagna Basu
Summary: This study characterized hvKP/CR-hvKP strains causing neonatal sepsis in terms of resistance and virulence. About 26% of the strains belonged to hvKP, with hvKP-K2 being the prevalent pathotype. The majority of the strains exhibited strong biofilm-forming and high serum resistance ability. Additionally, this study reported for the first time the NDM-1-producing hvKP ST11-K2 and ST15-K54 strains causing fatal neonatal sepsis.
MICROBIOLOGY SPECTRUM
(2023)
Article
Astronomy & Astrophysics
Bijan Saha
Summary: In this study, the role of a nonlinear spinor field in the evolution of the universe within a FLRW cosmological model is investigated. The FLRW models in both Cartesian and spherical coordinates are used. It is observed that the energy-momentum tensor of the spinor field has non-diagonal components when the FLRW model is given in spherical coordinates, which is not the case for Cartesian coordinates. These non-diagonal components are independent of both the nonlinearity of the spinor field and the curvature parameter k. The presence of these components imposes constraints on the spinor field. Open, flat, and closed geometries are considered, and the spinor field is used to simulate different types of sources including dark energies. Some qualitative numerical solutions are provided.
Article
Physics, Multidisciplinary
Bijan Saha
Summary: Within the Bianchi type-II cosmological model, the role of a spinor field in the evolution of the Universe was studied. It was found that even in the absence of spinor field nonlinearity, the components of the spinor field's energy-momentum tensor along the principal axis were different. The presence of nontrivial non-diagonal components of the energy-momentum tensor imposed restrictions on both the geometry of space-time and the spinor field itself. The choice of f(x3) determined whether the space-time was locally rotationally symmetric or isotropic. Depending on this choice, positive lambda(1) with f f''not equal 0 resulted in an oscillatory mode of evolution, while f' not equal 0 led to an accelerated mode of expansion.
ROMANIAN JOURNAL OF PHYSICS
(2023)
Article
Public, Environmental & Occupational Health
Rebecca Milton, David Gillespie, Calie Dyer, Khadijeh Taiyari, Maria J. Carvalho, Kathryn Thomson, Kirsty Sands, Edward A. R. Portal, Kerenza Hood, Ana Ferreira, Thomas Hender, Nigel Kirby, Jordan Mathias, Maria Nieto, William J. Watkins, Delayehu Bekele, Mahlet Abayneh, Semaria Solomon, Sulagna Basu, Ranjan K. Nandy, Bijan Saha, Kenneth Iregbu, Fatima Z. Modibbo, Stella Uwaezuoke, Rabaab Zahra, Haider Shirazi, Syed U. Najeeb, Jean-Baptiste Mazarati, Aniceth Rucogoza, Lucie Gaju, Shaheen Mehtar, Andre N. H. Bulabula, Andrew C. Whitelaw, Timothy R. Walsh, Grace J. Chan
Summary: This study aimed to determine the incidence and associations with neonatal sepsis and all-cause mortality in facility-born neonates in low-income and middle-income countries (LMICs). Findings reveal a high incidence of neonatal sepsis and its significant impact on mortality rates in LMICs.
LANCET GLOBAL HEALTH
(2022)
Article
Physics, Multidisciplinary
Bijan Saha
Summary: In this study, the role of different types of matter in the formation of configurations with spherical symmetries within a spherically symmetric space-time is examined. Types of matter considered include matter with barotropic equation of state, scalar field, electromagnetic field, and an interacting system of scalar and electromagnetic field. Field equations are solved using harmonic coordinates, and a straightforward method is proposed to predict the possible behavior of the metric functions based on the components of the energy-momentum tensor of the source field.
ROMANIAN JOURNAL OF PHYSICS
(2021)
Proceedings Paper
Physics, Mathematical
Bijan Saha
MATHEMATICAL MODELING AND COMPUTATIONAL PHYSICS 2017 (MMCP 2017)
(2018)
