2006/11/30 by Alejandro Satz · 1 citation
Physics and Astronomy · #gr-qc #hep-th
paper · pdf · doi:10.1088/0264-9381/24/7/003
published as Class.Quant.Grav.24:1719-1732,2007 · 16 pages, v3. Final published version with section 5 expanded
arxiv created 2007/04/20 · arxiv updated 2009/12/01
The transition probability in first-order perturbation theory for an Unruh-DeWitt detector coupled to a massless scalar field in Minkowski space is calculated. It has been shown recently that the conventional iε regularisation prescription for the correlation function leads to non-Lorentz invariant results for the transition rate, and a different regularisation, involving spatial smearing of the field, has been advocated to replace it. We show that the non-Lorentz invariance arises solely from the assumption of sudden switch-on and switch-off of the detector, and that when the model includes a smooth switching function the results from the conventional regularisation are both finite and Lorentz invariant. The sharp switching limit of the model is also discussed, as well as the falloff properties of the spectrum for large frequencies.