arXiv subjects

Yi-Da Li

Publications and source records attributed to Yi-Da Li.

4 recordsLinked to original sources

arXiv2024

Isospectral local Hermitian theory for the $\mathcal{PT}$-symmetric $i\phi^3$ quantum field theory

We propose a new method to calculate perturbatively the isospectral Hermitian theory for the $\mathcal{PT}$-symmetric $i\phi^3$ quantum field theory in $d$ dimensions, whose result is local. The result of the new method in $1$ dimension reproduces our previous result in the $ix^3$ quantum mechanics, and the new method can be seen as a generalization of our previous method to quantum field theory. We also find the isospectral local Hermitian theory has the same form in all dimensions and differs in coefficients only, and our previous results in quantum mechanics can be used directly to determine the form of the isospectral local Hermitian quantum field theory.

hep-th↗

arXiv2023

PT-Symmetric Quantum Field Theory in Path Integral Formalism and Arbitrariness Problem

Perturbative PT-symmetric quantum field theories with anti-Hermitian and P-odd interaction terms are studied in path integral formalism and the i phi^3 model is calculated in detail. The nonlocal field transformation induced by the C operator and corresponding transformations to Hermitian theories are given systematically, which are manifestly 4-dimensional invariant. It is found that the i phi^3 model can be transformed into infinitely many physically inequivalent Hermitian theories with different S matrices under above nonlocal transformations. Similar problem caused by nonlocal tranformations in Hermitian quantum field theories is also discussed. 0-dimensional models are studied numerically to verify the validity of those transformations. We put forward the question of physical meaning of PT-symmetric quantum field theory based on the arbitrariness caused by the seemingly inevitable nonlocality.

hep-th↗

arXiv2023

Isospectral Local Hamiltonians for Perturbative PT-symmetric Hamiltonians

A new method to work out the Hermitian correspondence of a PT-symmetric quantum mechanical Hamiltonian is proposed. In contrast to the conventional method, the new method ends with a local Hamiltonian of the form p^2/2+m^2x^2/2+v(x) without any higher-derivative terms. This method is demonstrated in the perturbative regime. Possible extensions to multi-variable quantum mechanics and quantum field theories are discussed.

hep-th↗

arXiv2020

Beyond Symmetries : Anomalies in Transverse Ward--Takahashi Identities

Anomalies in transverse Ward--Takahashi identities are studied, allowing discussion of the feasibility of anomalies arising in general non-symmetry Ward--Takahashi identities. We adopt the popular Fujikawa's method and rigorous dimensional renormalization to verify the existence of transverse anomalies to one-loop order and any loop order, respectively. The arbitrariness of coefficients of transverse anomalies is revealed, and a way out is also proposed after relating transverse anomalies to Schwinger terms and comparing symmetry and non-symmetry anomalies. Papers that claim the non-existence of transverse anomalies are reviewed to find anomalies hidden in their approaches. The role played by transverse anomalies is discussed.

hep-th↗