Margolus-Levitin speed limit across quantum to classical regimes based on trace distance

The classical version of Mandelstam-Tamm speed limit based on the Wigner function in phase space is reported by B. Shanahan et al. [Phys. Rev. Lett. 120, 070401 (2018)]. In this paper, the Margolus-Levitin speed limit across the quantum-to-classical transition is given in phase space based on the trace distance. The Margolus-Levitin speed limit is set by the Schatten L1 norm of the generator of time dependent evolution for both the quantum and classical domains. As an example, the time-dependent harmonic oscillator is considered to illustrate the result.

Covariant Approach to the No-ghost Theorem in Massive Gravity

We discuss the no-ghost theorem in the massive gravity in a covariant manner. Using the BRST formalism and St{u}ckelberg fields, we first clarify how the Boulware-Deser ghost decouples in the massive gravity theory with Fierz-Pauli mass term. Here we find that the crucial point in the proof is that there is no higher (time) derivative for the St{u}ckelberg `scalar field. We then analyze the nonlinear massive gravity proposed by de Rham, Gabadadze and Tolley, and show that there is no ghost for general admissible backgrounds. In this process, we find a very nontrivial decoupling limit for general backgrounds. We end the paper by demonstrating the general results explicitly in a nontrivial example where there apparently appear higher time derivatives for St{u}ckelberg scalar field, but show that this does not introduce the ghost into the theory.

BV analysis for covariant and non-covariant actions

The equivalence between the covariant and the non-covariant version of a constrained system is shown to hold after quantization in the framework of the field-antifield formalism. Our study covers the cases of Electromagnetism and Yang-Mills fields and sheds light on some aspects of the Faddeev-Popov method, for both the coratiant and non-covariant approaches, which had not been fully clarified in the literature.

Covariant Schwinger terms

There exist t