Quantum Theory Of Gravitational Field Research Articles

Linear dynamics and classical tests of the gravitational quantum field theory

Linear dynamics and classical tests of the gravitational quantum field theory

Gravidynamics, spinodynamics and electrodynamics within the framework of gravitational quantum field theory

By noticing the fact that the charged leptons and quarks in the standard model are chirality-based Dirac spinors since their weak interaction violates maximally parity symmetry though they behave as Dirac fermions in electromagnetic interaction, we show that such a chirality-based Dirac spinor possesses not only electric charge gauge symmetry U(1) but also inhomogeneous spin gauge symmetry WS(1,3) = SP(1,3)$\rtimes$W$^{1,3}$, which reveals the nature of gravity and spacetime. The gravitational force and spin gauge force are governed by the gauge symmetries $W^{1,3}$ and SP(1,3), respectively, and a biframe spacetime with globally flat Minkowski spacetime as base spacetime and locally flat gravigauge spacetime as a fiber is described by the gravigauge field through emergent non-commutative geometry. The gauge-geometry duality and renormalizability in gravitational quantum field theory (GQFT) are carefully discussed. A detailed analysis and systematic investigation on gravidynamics and spinodynamics as well as electrodynamics are carried out within the framework of GQFT. A full discussion on the generalized Dirac equation and Maxwell equation as well as Einstein equation and spin gauge equation is made in biframe spacetime. New effects of gravidynamics as extension of general relativity are particularly analyzed. All dynamic equations of basic fields are demonstrated to preserve the spin gauge covariance and general coordinate covariance due to the spin gauge symmetry and emergent general linear group symmetry GL(1,3,R), so they hold naturally in any spinning reference frame and motional reference frame.

Hyperunified field theory and Taiji program in space for GWD

In this paper, I present the recently established hyperunified field theory (HUFT)[Formula: see text] for all basic forces and elementary particles within the framework of gravitational quantum field theory (GQFT)[Formula: see text] in hyper-space–time. GQFT treats gravity as a gauge theory in the framework of quantum field theory to avoid the long term obstacle between general relativity and quantum mechanics. HUFT is built based on the guiding principle: the dimension of hyper-space–time correlates to intrinsic quantum numbers of basic building blocks of nature, and the action describing the laws of nature obeys the gauge invariance and coordinate independence, which is more fundamental than that proposed by Einstein for general relativity. The basic gravitational field is defined in biframe hyper-space–time as a bicovariant vector field, it is a gauge-type hyper-gravifield rather than a metric field. HUFT is characterized by a bimaximal Poincaré and hyper-spin gauge symmetry [Formula: see text] with a global and local conformal scaling invariance in biframe hyper-space–time. The gravitational origin of gauge symmetry is revealed through the hyper-gravifield that plays an essential role as a Goldstone-like field, which enables us to demonstrate the gauge-gravity and gravity-geometry correspondences and to corroborate the gravitational gauge-geometry duality with an emergent hidden general linear group symmetry [Formula: see text]. The Taiji Program in Space for the gravitational wave detection in China[Formula: see text] is briefly outlined.

Gravity and Spin Forces in Gravitational Quantum Field Theory**Supported in part by the National Science Foundation of China (NSFC) under Grant Nos. 11690022 and 11475237, Strategic Priority Research Program of the Chinese Academy of Sciences (CAS), under Grant No. XDB23030100, Key Research Program QYZDYSSW-SYS007, and the CAS Center for Excellence in Particle Physics (CCEPP)

In the new framework of gravitational quantum field theory (GQFT) with spin and scaling gauge invariance developed in Phys. Rev. D 93 (2016) 024012-1, we make a perturbative expansion for the full action in a background field which accounts for the early inflationary universe. We decompose the bicovariant vector fields of gravifield and spin gauge field with Lorentz and spin symmetries SO(1,3) and SP(1,3) in biframe spacetime into SO(3) representations for deriving the propagators of the basic quantum fields and extract their interaction terms. The leading order Feynman rules are presented. A tree-level 2 to 2 scattering amplitude of the Dirac fermions, through a gravifield and a spin gauge field, is calculated and compared to the Born approximation of the potential. It is shown that the Newtonʼs gravitational law in the early universe is modified due to the background field. The spin dependence of the gravitational potential is demonstrated.

Maximal symmetry and mass generation of Dirac fermions and gravitational gauge field theory in six-dimensional spacetime**Supported by National Science Foundation of China (NSFC) (11690022, 11475237, 11121064) and Strategic Priority Research Program of the Chinese Academy of Sciences (XDB23030100) as well as the CAS Center for Excellence in Particle Physics (CCEPP)

The relativistic Dirac equation in four-dimensional spacetime reveals a coherent relation between the dimensions of spacetime and the degrees of freedom of fermionic spinors. A massless Dirac fermion generates new symmetries corresponding to chirality spin and charge spin as well as conformal scaling transformations. With the introduction of intrinsic W-parity, a massless Dirac fermion can be treated as a Majorana-type or Weyl-type spinor in a six-dimensional spacetime that reflects the intrinsic quantum numbers of chirality spin. A generalized Dirac equation is obtained in the six-dimensional spacetime with a maximal symmetry. Based on the framework of gravitational quantum field theory proposed in Ref. [] with the postulate of gauge invariance and coordinate independence, we arrive at a maximally symmetric gravitational gauge field theory for the massless Dirac fermion in six-dimensional spacetime. Such a theory is governed by the local spin gauge symmetry SP(1,5) and the global Poincaré symmetry P(1,5)=SO(1,5)⋉P1,5 as well as the charge spin gauge symmetry SU(2). The theory leads to the prediction of doubly electrically charged bosons. A scalar field and conformal scaling gauge field are introduced to maintain both global and local conformal scaling symmetries. A generalized gravitational Dirac equation for the massless Dirac fermion is derived in the six-dimensional spacetime. The equations of motion for gauge fields are obtained with conserved currents in the presence of gravitational effects. The dynamics of the gauge-type gravifield as a Goldstone-like boson is shown to be governed by a conserved energy-momentum tensor, and its symmetric part provides a generalized Einstein equation of gravity. An alternative geometrical symmetry breaking mechanism for the mass generation of Dirac fermions is demonstrated.

We have confidence to lead gravitational-wave science: an interview with Yueliang Wu

Abstract Yueliang Wu, chief scientist of Taiji Program, is a well-known theoretical physicist and the Vice-President of the University of Chinese Academy of Sciences (UCAS). Taiji Program, initially proposed in 2008, is one of China's ambitious plans to observe gravitational waves. Obtaining his Ph.D. at the Institute of Theoretical Physics (ITP) under the Chinese Academy of Sciences (CAS) in 1987, Wu had been working at Dortmund University and Mainz University in Germany and Carnegie-Mellon University and the Ohio-State University in the USA. In 1996, he joined the ITP and became its director in 2007. He has also served as the Director of the Kavli Institute for Theoretical Physics China at the CAS since 2006. In 2007, he was elected as a CAS member.  Wu's research is focused on elementary particle physics, quantum field theory, symmetry principle and cosmophysics. In recent years, he has been proposing a gravitational quantum field theory as a new approach to reconciling the general theory of relativity and quantum mechanics. The most fundamental unanswered question of the general theory of relativity is how general relativity can be reconciled with the laws of quantum physics to produce a complete and self-consistent theory of quantum gravity. To extend the general relativity to realize the reconciliation, Wu suggested a basic gravitational field be needed in the future model.  Since 2012, he, together with Wenrui Hu, has been working as Taiji Program's chief scientist and promoting nationwide gravitational-wave research. National Science Review (NSR) spoke with Wu about the future of gravitational-wave research, the development of China's nationwide gravitational-wave studies and particularly the progress of Taiji Program.

Particle Scattering in Loop Quantum Gravity

We devise a technique for defining and computing -point functions in the context of a background-independent gravitational quantum field theory. We construct a tentative implementation of this technique in a perturbatively finite model defined using spin foam techniques in the context of loop quantum gravity.

Canonical Quantum Theory of Gravitational Field with Higher Derivatives. III: A Formulation with an Additional BRS Invariance

Canonical Quantum Theory of Gravitational Field with Higher Derivatives. III: A Formulation with an Additional BRS Invariance

Canonical Quantum Theory of Gravitational Field with Higher Derivatives. II: Asymptotic Fields and Unitarity Problem

Canonical Quantum Theory of Gravitational Field with Higher Derivatives. II: Asymptotic Fields and Unitarity Problem

Canonical Quantum Theory of Gravitational Field with Higher Derivatives

Canonical Quantum Theory of Gravitational Field with Higher Derivatives

A Possible Mechanism of Ghost Confinement in a Renormalizable Quantum Gravity

In recent years the quantum theory of gravitational field has been developed l ) in the framework of the Kugo-Ojima formalism') of the canonical local indefinite-metric quantum field theory of Yang-Mills fields and the unitarity of the physical S-matrix was established. But the renormalizability is completely unclear. On the other hand, the quantum theory of the quadratic gravitational theory (Einstein's gravitational theory supplemented with terms containing R' and RvRV) was shown to be renormalizable by Stelle several years ago. 3 ),4) But this theory possesses a massive tensor ghost field in its asymptotic fields and the unitarity of the physical S -matrix is violated. The purpose of this paper is to suggest a possible mechanism of the confinement of the massive tensor ghost field in the renormalizable quadratic quantum gravity. Our arguments are based on the Kugo-Ojima formulation of Yang-Mills fields. Let us start with the lagrangian (we restrict our discussion to the Landau gauge)

Subsidiary conditions and physical S-matrix unitarity in indefinite-metric quantum gravitation theory

The quantum theory of gravitational fields is formulated in a manifestly Lorentz covariant manner in the framework of indefinite-metric quantum field theory. The physical state subspace is defined by the two subsidiary conditions Q B|phys〉 = Q c|phys〉 = 0, where the conserved charges Q B and Q c are the generators of the BRS transformation ond of the Faddeev-Popov ghost scale transformation, respectively. By clarifying the metric structures of the Fock space of asymptotic fields with help of the Ward-Takahashi identities, the physical S-matrix unitarity is established in just the same way as in the canonical theory of Yang-Mills fields.