Framework for finite alternative theories to a quantum field theory. II-Unitarity
نویسنده
چکیده
We generalized the ’t Hooft-Veltman method of unitary regulators to put forward a path-integral framework for finite, alternative theories to a given quantum field theory. And we demonstrated that the proposed framework is feasible by providing a finite alternative to the quantum field theory of a single, self-interacting real scalar field. Here we give two properties of self-energy that make the corresponding scattering matrix unitary. We show that the perturbative self-energy has these two properties at least up to the second order in the coupling constant. Suggested short title: Framework for finite alternative theories ... PACS number: 11.90.+t
منابع مشابه
Noncommutative Dipole Field Theories And Unitarity
We extend the argument of Gomis and Mehen for violation of unitarity in field theories with space-time noncommutativity to dipole field theories. In dipole field theories with a timelike dipole vector, we present 1-loop amplitudes that violate the optical theorem. A quantum mechanical system with nonlocal potential of finite extent in time also shows violation of unitarity.
متن کاملFramework for finite alternative theories to a quantum field theory
Using the path-integral formalism, we generalize the ’t HooftVeltman method of unitary regulators to obtain a framework for finite alternative quantum theories to a given quantum field theory. Feynman-like rules of such a finite alternative quantum theory lead to regularized perturbative expansions of the original Green functions, which are causal, and involve no additional free particles. To d...
متن کاملUnitarity of Noncommutative Field Theories from String Theory∗
We improve the study of the lack of perturbative unitarity of noncommutative space-time quantum field theories derived from open string theory in electric backgrounds, enforcing the universality of the mechanism by which a tachyonic branch cut appears when the Seiberg-Witten limit freezes the string in an unstable vacuum. The main example is realized in the context of the on-shell four-tachyon ...
متن کاملOn Four-Dimensional Gauge Theories from Type II Superstrings
We study the four-dimensional gauge theories which are associated with classical vacua of the type II superstring, i.e. which correspond to a superconformal field theory on the world sheet. Using the fact that gauge symmetry arises from a supersymmetric affine Kac-Moody algebra, and demanding unitarity of the underlying world-sheet field theory, we show that no such vacua can yield the particle...
متن کاملUnitary Issues in Some Higher Derivative Field Theories
We analyze the unitarity properties of higher derivative quantum field theories which are free of ghosts and ultraviolet singularities. We point out that in spite of the absence of ghosts most of these theories are not unitary. This result confirms the difficulties of finding a consistent quantum field theory of quantum gravity.
متن کامل