caa a22 4500 445320435 CHVBK 20180317142702.0 cr unu---uuuuu 170323e20111201xx s 000 0 eng 10.1007/s00023-011-0111-6 doi (NATIONALLICENCE)springer-10.1007/s00023-011-0111-6 Approximate KMS States for Scalar and Spinor Fields in Friedmann-Robertson-Walker Spacetimes [Elektronische Daten] [Claudio Dappiaggi, Thomas-Paul Hack, Nicola Pinamonti] We construct and discuss Hadamard states for both scalar and Dirac spinor fields in a large class of spatially flat Friedmann-Robertson-Walker spacetimes characterised by an initial phase either of exponential or of power-law expansion. The states we obtain can be interpreted as being in thermal equilibrium at the time when the scale factor a has a specific value a = a 0. In the case a 0 =0, these states fulfil a strict KMS condition on the boundary of the spacetime, which is either a cosmological horizon or a Big Bang hypersurface. Furthermore, in the conformally invariant case, they are conformal KMS states on the full spacetime. However, they provide a natural notion of an approximate KMS state also in the remaining cases, especially for massive fields. On the technical side, our results are based on a bulk-to-boundary reconstruction technique already successfully applied in the scalar case and here proven to be suitable also for spinor fields. The potential applications of the states we find range over a broad spectrum, but they appear to be suited to discuss in particular thermal phenomena such as the cosmic neutrino background or the quantum state of dark matter. Springer Basel AG, 2011 Dappiaggi Claudio II. Institut für Theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761, Hamburg, Germany aut Hack Thomas-Paul II. Institut für Theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761, Hamburg, Germany aut Pinamonti Nicola Dipartimento di Matematica, Università di Roma "Tor Vergata”, Via della Ricerca Scientifica, 00133, Rome, Italy aut Annales Henri Poincaré SP Birkhäuser Verlag Basel 12/8(2011-12-01), 1449-1489 1424-0637 12:8<1449 2011 12 23 https://doi.org/10.1007/s00023-011-0111-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00023-011-0111-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Dappiaggi Claudio II. Institut für Theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761, Hamburg, Germany aut NATIONALLICENCE 700 1- Hack Thomas-Paul II. Institut für Theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761, Hamburg, Germany aut NATIONALLICENCE 700 1- Pinamonti Nicola Dipartimento di Matematica, Università di Roma "Tor Vergata”, Via della Ricerca Scientifica, 00133, Rome, Italy aut NATIONALLICENCE 773 0- Annales Henri Poincaré SP Birkhäuser Verlag Basel 12/8(2011-12-01), 1449-1489 1424-0637 12:8<1449 2011 12 23 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer