Complex poles in the ghost propagator induce persistent interactions at asymptotic times, rendering negative-norm ghost states indistinguishable from superpositions of positive-norm multi-particle states and eliminating free asymptotic ghost particles.
Quantum mechanics of 4-derivative theories
4 Pith papers cite this work. Polarity classification is still indexing.
4
Pith papers citing it
abstract
A renormalizable theory of gravity is obtained if the dimension-less 4-derivative kinetic term of the graviton, which classically suffers from negative unbounded energy, admits a sensible quantisation. We find that a 4-derivative degree of freedom involves a canonical coordinate with unusual time-inversion parity, and that a correspondingly unusual representation must be employed for the relative quantum operator. The resulting theory has positive energy eigenvalues, normalisable wave functions, unitary evolution in a negative-norm configuration space. We present a formalism for quantum mechanics with a generic norm.
citation-role summary
background 2
citation-polarity summary
years
2026 4roles
background 2polarities
background 2representative citing papers
A quantum ghost coupled polynomially to a harmonic oscillator has unitary evolution and a stable vacuum because a conserved quantity possesses a positive discrete spectrum.
Ghosts lack asymptotic particle interpretation due to interference and different Riemann-sheet pole structures compared to decaying unstable particles, with finite-time effects producing narrower resonances and higher peaks.
Gauge-invariant analysis of scalar cosmological perturbations in quadratic gravity shows that Newtonian-gauge exponential growth is a gauge artifact, with perturbations remaining well-behaved in other gauges.
citing papers explorer
-
Gauge-independent approach to inflation in quadratic gravity
Gauge-invariant analysis of scalar cosmological perturbations in quadratic gravity shows that Newtonian-gauge exponential growth is a gauge artifact, with perturbations remaining well-behaved in other gauges.