Fourth Order Theories Without Ghosts

2000/01/19 by Philip D. Mannheim, Mannheim, Philip D., Aharon Davidson +1
Physics and Astronomy · #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Theory (hep-th) #gr-qc #hep-th

paper · pdf · doi:10.48550/arxiv.hep-th/0001115

RevTeX, 8 pages

arxiv created 2000/01/19 · arxiv updated 2009/11/30

Abstract

Using the Dirac constraint method we show that the pure fourth-order Pais-Uhlenbeck oscillator model is free of observable negative norm states. Even though such ghosts do appear when the fourth order theory is coupled to a second order one, the limit in which the second order action is switched off is found to be a highly singular one in which these states move off shell. Given this result, construction of a fully unitary, renormalizable, gravitational theory based on a purely fourth order action in 4 dimensions now appears feasible.

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