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Ying-Qiu Gu

Publications and source records attributed to Ying-Qiu Gu.

28 records · Page 2Linked to original sources
arXiv2009

The Series Solution to the Metric of Stationary Vacuum with Axisymmetry

The multipole moments method is not only an aid to understand the deformation of the space-time, but also an effective tool to solve the approximate solutions of the Einstein field equation. However, The usual multipole moments are recursively defined by a sequence of symmetric and trace-free tensors, which are inconvenient for practical resolution. In this paper, we develop a simple procedure to generate the series solutions, and propose a method to identify the free parameters by taking the Schwarzschild metric as a standard ruler. Some well known examples are analyzed and compared with the series solutions.

physics.gen-ph↗
arXiv2008

How to Measure the Cosmic Curvature

The conventional method to determine the cosmic curvature is to measure the total mass density $Ω_{\rm tot}$. Unfortunately the observational $Ω_{\rm tot}$ is closely near the critical value 1. The computation of this paper shows that $Ω_{\rm tot}\approx 1$ is an inevitable result for the young universe independent of the spatial topology. So the mass density is not a good criterion to determine the cosmic curvature. In this paper, we derive a new criterion based on the galactic distribution with respect to redshift $z$, which only depends on the cosmological principle and geometry. The different type of spatial topology will give different results, then the case can be definitely determined.

gr-qc↗
arXiv2007

Structure of the Star with Ideal Gases

In this paper, we provide a simplified stellar structure model for ideal gases, in which the particles are only driven by gravity. According to the model, the structural information of the star can be roughly solved by the total mass and radius of a star. To get more accurate results, the model should be modified by introducing other interaction among particles and rotation of the star.

physics.gen-ph↗
arXiv2007

A Cosmological Model with Dark Spinor Source

In this paper, we discuss the system of Friedman-Robertson-Walker metric coupling with massive nonlinear dark spinors in detail, where the thermodynamic movement of spinors is also taken into account. The results show that, the nonlinear potential of the spinor field can provide a tiny negative pressure, which resists the Universe to become singular. The solution is oscillating in time and closed in space, which approximately takes the following form $$ g_{μν}=\bar R^2(1-δ\cos t)^2\diag(1,-1,-\sin^2r ,-\sin^2r \sin^2θ), $$ with $\bar R= (1\sim 2)\times 10^{12}$ light year, and $δ=0.96\sim 0.99$. The present time is about $t\sim 18^\circ$.

gr-qc↗
arXiv2007

Local Lorentz Transformation and "Lorentz Violation"

Some solutions to the anomalies of ultra high energy cosmic-ray(UHECR) and TeV $γ$-rays require disturbed non-quadratic dispersion relations, which suggest the Lorentz violation. Also, some new theories such as quantum gravity, string theory and the standard model extension imply the Lorentz violation. In this paper, we derive some transformation laws for the classical parameters of nonlinear field system, and then provide their dispersion relations. These dispersion relations also have non-quadratic form but keep the Lorentz invariance. The analysis of this paper may be helpful for understanding the quantum theory and the plausible Lorentz violation.

physics.gen-ph↗
arXiv2007

Exact Vacuum Solutions to the Einstein Equation

In this paper, we present a framework for getting a series of exact vacuum solutions to the Einstein equation. This procedure of resolution is based on a canonical form of the metric. According to this procedure, the Einstein equation can be reduced to some 2-dimensional Laplace-like equations or rotation and divergence equations, which are much convenient for the resolution.

physics.gen-ph↗
arXiv2007

Eigen Equation of the Nonlinear Spinor

How to effectively solve the eigen solutions of the nonlinear spinor field equation coupling with some other interaction fields is important to understand the behavior of the elementary particles. In this paper, we derive a simplified form of the eigen equation of the nonlinear spinor, and then propose a scheme to solve their numerical solutions. This simplified equation has elegant and neat structure, which is more convenient for both theoretical analysis and numerical computation.

physics.gen-ph↗
arXiv2006

The covariant derivatives and energy momentum tensor of spinors

To understand the coupling behavior of the spinor with spacetime, the explicit form of the energy-momentum tensor of the spinor in curved spacetime is important. This problem seems to be overlooked for a long time. In this paper we derive the explicit form of energy momentum tensors and display some equivalent but simple forms of the covariant derivatives for both the Weyl spinor and the Dirac bispinor in curved spacetime.

gr-qc↗
arXiv2006

New Approach to $N$-body Relativistic Quantum Mechanics

In this paper, we propose a new approach to the relativistic quantum mechanics for many-body, which is a self-consistent system constructed by juxtaposed but mutually coupled nonlinear Dirac's equations. The classical approximation of this approach provides the exact Newtonian dynamics for many-body, and the nonrelativistic approximation gives the complete Schrödinger equation for many-body.

hep-th↗