scholarly journals FERMION RESONANCE IN QUANTUM FIELD THEORY

2007 ◽  
Vol 22 (33) ◽  
pp. 2511-2519 ◽  
Author(s):  
M. O. GONCHAR ◽  
A. E. KALOSHIN ◽  
V. P. LOMOV
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
The Self ◽  
Quantum Field ◽  
Energy Contribution ◽  
Self Energy

We accurately derive the fermion resonance propagator by means of Dyson summation of the self-energy contribution. It turns out that the relativistic fermion resonance differs essentially from its boson analog.

scholarly journals Note on the Self-Energy in Quantum Field Theory

1969 ◽  
Vol 42 (6) ◽  
pp. 1468-1474
Author(s):  
Tadashi Imamura ◽  
Kazuo Okajima ◽  
Sigenobu Sunakawa
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
The Self ◽  
Quantum Field ◽  
Self Energy

scholarly journals Converting neutron stars into strange stars: Instanton model

2014 ◽  
Vol 23 (09) ◽  
pp. 1450078
Author(s):  
Victor Ts. Gurovich ◽  
Leonid G. Fel
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Detonation Wave ◽  
Neutron Stars ◽  
Quark Matter ◽  
Quantum Fluctuation ◽  
The Self ◽  
Quantum Field ◽  
Spherical Detonation ◽  
Self Similar

We calculate the quasiclassical probability to emerge the quantum fluctuation which gives rise to the quark-matter drop with interface propagating as the self-similar spherical detonation wave (DN) in the ambient nuclear matter. For this purpose, we make use of instanton method which is known in the quantum field theory.

On the Self-Energies of Quantum Field Theory

1950 ◽  
Vol 80 (6) ◽  
pp. 987-989 ◽  
Author(s):  
George Snow ◽  
Hartland S. Snyder
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
The Self ◽  
Quantum Field

STABLE QUASIPARTICLE PICTURE IN THERMAL QUANTUM FIELD PHYSICS

1994 ◽  
Vol 09 (10) ◽  
pp. 1703-1729 ◽  
Author(s):  
H. CHU ◽  
H. UMEZAWA
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Degrees Of Freedom ◽  
Fock Space ◽  
Quantum Field ◽  
Self Energy ◽  
Vector Algebra ◽  
Physical Particle ◽  
Usual Quantum ◽  
Definition Of

It is well known that physical particles are thermally dissipative at finite temperature. In this paper we reformulate both the equilibrium and nonequilibrium thermal field theories in terms of stable quasiparticles. We will redefine the thermal doublets, the double tilde conjugation rules and the thermal Bogoliubov transformations so that our theory can be consistent for most general situations. All operators, including the dissipative physical particle operators, are realized in a Fock space defined by the stable quasiparticles. The propagators of the physical particles are expressed in terms of the operators of such stable quasiparticles, which is a simple diagonal matrix with the diagonal elements being the temporal step functions, same as the propagators in the usual quantum field theory without thermal degrees of freedom. The proper self-energies are also expressed in terms of these stable quasiparticle propagators. This formalism inherits the definition of on-shell self-energy in the usual quantum field theory. With this definition, a self-consistent renormalization is formulated which leads to quantum Boltzmann equation and the entropy law. With the aid of a doublet vector algebra we have an extremely simple recipe for computing Feynman diagrams. We apply this recipe to several examples of equilibrium and nonequilibrium two-point functions, and to the kinetic equation for the particle numbers.

RELATIVISTIC QUANTUM FIELD THEORY FOR CONDENSED SYSTEMS (II): RENORMALIZATION PROCEDURE

2003 ◽  
Vol 17 (30) ◽  
pp. 5713-5723 ◽  
Author(s):  
HIROYUKI MATSUURA
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Electric Charge ◽  
Relativistic Quantum ◽  
Free Field ◽  
Mass Shift ◽  
Quantum Field ◽  
Relativistic Quantum Field Theory ◽  
Self Energy ◽  
Physical Mass

We proposed Atomic Schwinger–Dyson method (ASD method) in previous paper, which was a nonperturbative and relativistic quantum field theory for a finite baryon density. We think it is important to show the significance of renormarization in order to get real physical predictions. Moreover, the real value of physical mass, electric charge and wave function are completely different from those of the non-renormalized electron and photon in mean field theory, since there are many of the particle-antiparticle creations and annihilations, particle-hole excitation, and Pauli blocking, which give an effect on bare mass, electric charge, polarization of vacuum, and self-energy. In this paper, we shows that ASD method is renormalizable theory, and that photon condensation of ASD method gave rise to Coulomb's potential and the mass shift of electron. The interacting photon and electron fields, which have physical mass and electric charge, are expressed as generalized free field equations by using the mass shift and the self-energy of those particles. We obtain the expression of an exact solution of these particles on the basis of the Green functional method.

scholarly journals Convergence in Quantum Field Theory without Use of Renormalization

2019 ◽  
Author(s):  
Biswaranjan Dikshit
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Quantum Electrodynamics ◽  
Ad Hoc ◽  
Probability Amplitude ◽  
Quantum Field ◽  
Counter Term ◽  
Self Energy ◽  
Calculated Probability ◽  
Conventional Methods

In quantum field theory (QFT), it is well known that when Feynman diagrams containing loops are evaluated to account for self interactions, probability amplitude comes out to be infinite which is physically not admissible. So, to make the QFT convergent, various renormalization methods are conventionally followed in which an additional (infinite) counter term is postulated which neutralizes the original infinity generated by diagram. The resulting finite values of amplitudes have agreed with experiments with surprising accuracy. However, proponents of renormalization methods acknowledged that this ad-hoc procedure of subtraction of infinity from infinity to reach at a finite value is not at all satisfactory and there is no physical basis for bringing in the counter term. So, it is desirable to establish a method in QFT which does not generate any infinite term (thus not requiring renormalization), but which predicts same results as conventional methods do. In this paper, we describe such a technique taking self interaction quantum electrodynamics diagram representing electron or photon self energy. In our method, no problem of infinity arises and hence renormalization is not necessary. Still, the dependence of calculated probability amplitude on physical variables in our technique comes out to be same as conventional methods. Using similar procedure, we hope, the problem of non-renormalizability of quantum gravity may be solved in future.

scholarly journals Quantum spectral dimension in quantum field theory

2016 ◽  
Vol 25 (05) ◽  
pp. 1650058 ◽  
Author(s):  
Gianluca Calcagni ◽  
Leonardo Modesto ◽  
Giuseppe Nardelli
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Transition Amplitude ◽  
Energy Transition ◽  
Dispersion Relations ◽  
Spectral Dimension ◽  
Quantum Field ◽  
Self Energy ◽  
Dimension Formula ◽  
A Value

We reinterpret the spectral dimension of spacetimes as the scaling of an effective self-energy transition amplitude in quantum field theory (QFT), when the system is probed at a given resolution. This picture has four main advantages: (a) it dispenses with the usual interpretation (unsatisfactory in covariant approaches) where, instead of a transition amplitude, one has a probability density solving a nonrelativistic diffusion equation in an abstract diffusion time; (b) it solves the problem of negative probabilities known for higher-order and nonlocal dispersion relations in classical and quantum gravity; (c) it clarifies the concept of quantum spectral dimension as opposed to the classical one. We then consider a class of logarithmic dispersion relations associated with quantum particles and show that the spectral dimension [Formula: see text] of spacetime as felt by these quantum probes can deviate from its classical value, equal to the topological dimension [Formula: see text]. In particular, in the presence of higher momentum powers it changes with the scale, dropping from [Formula: see text] in the infrared (IR) to a value [Formula: see text] in the ultraviolet (UV). We apply this general result to Stelle theory of renormalizable gravity, which attains the universal value [Formula: see text] for any dimension [Formula: see text].

scholarly journals DIRAC EQUATION FOR QUASI-PARTICLES IN GRAPHENE AND QUANTUM FIELD THEORY OF THEIR COULOMB INTERACTION

2012 ◽  
Vol 26 (21) ◽  
pp. 1242005 ◽  
Author(s):  
RIAZUDDIN
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Dirac Equation ◽  
Coulomb Interaction ◽  
Group Analysis ◽  
Fermi Velocity ◽  
Quantum Field ◽  
Renormalization Group Analysis ◽  
Self Energy ◽  
Conserved Currents

There is evidence for existence of massless Dirac quasiparticles in graphene, which satisfy Dirac equation in (1+2) dimensions near the so called Dirac points which lie at the corners at the graphene's brilluoin zone. We revisit the derivation of Dirac equation in (1+2) dimensions obeyed by quasiparticles in graphene near the Dirac points. It is shown that parity operator in (1+2) dimensions play an interesting role and can be used for defining "conserved" currents resulting from the underlying Lagrangian for Dirac quasiparticles in graphene which is shown to have UA(1) × UB(1) symmetry. Further the quantum field theory (QFT) of Coulomb interaction of 2D graphene is developed and applied to vacuum polarization and electron self-energy and the renormalization of the effective coupling g of this interaction and Fermi velocity vf which has important implications in the renormalization group analysis of g and vf.

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