129 citations · 1.4k across the 48 of their papers we have counts for
48 papers
Anti-Instability of Complex Ghost
Jisuke Kubo, Taichiro Kugo
We argue that Lee-Wick's complex ghost appearing in any higher derivative theory is stable and its asymptotic field exists. It may be more appropriate to call it ``anti-unstable" i…
Unitarity Violation in Field Theories of Lee-Wick's Complex Ghost
Jisuke Kubo, Taichiro Kugo
Theories with fourth-order derivatives, including the Lee-Wick finite QED model and Quadratic Gravity, have a better UV behaviour, but the presence of negative metric ghost modes e…
Covariant BRST Quantization of Unimodular Gravity I -- Formulation with antisymmetric tensor ghosts --
Taichiro Kugo, Ryuichi Nakayama, Nobuyoshi Ohta
Unimodular gravity (UG) is an interesting theory that may explain why the cosmological constant is extremely small, in contrast to general relativity (GR). The theory has only the…
Covariant BRST Quantization of Unimodular Gravity II -- Formulation with a vector antighost --
Taichiro Kugo, Ryuichi Nakayama, Nobuyoshi Ohta
In our previous paper, we have presented a covariant BRST quantization of unimodular gravity which may account for the smallness of the cosmological constant, and have shown that t…
BRST Quantization of General Relativity in Unimodular Gauge and Unimodular Gravity
Taichiro Kugo, Ryuichi Nakayama, Nobuyoshi Ohta
Unimodular gravity (UG) is an important theory which may explain the smallness of the cosmological constant. To get insight into the covariant quantization of UG, we discuss the BR…
Noether Currents and Maxwell-type Equations of Motion in Higher Derivative Gravity Theories
Taichiro Kugo
In general coordinate invariant gravity theories whose Lagrangians contain arbitrarily high order derivative fields, the Noether currents for the global translation and for the Nak…