caa a22 4500 445320346 CHVBK 20180317142702.0 cr unu---uuuuu 170323e20110501xx s 000 0 eng 10.1007/s00023-011-0091-6 doi (NATIONALLICENCE)springer-10.1007/s00023-011-0091-6 Ground States in the Spin Boson Model [Elektronische Daten] [David Hasler, Ira Herbst] We prove that the Hamiltonian of the model describing a spin which is linearly coupled to a field of relativistic and massless bosons, also known as the spin-boson model, admits a ground state for small values of the coupling constant λ. We show that the ground-state energy is an analytic function of λ and that the corresponding ground state can also be chosen to be an analytic function of λ. No infrared regularization is imposed. Our proof is based on a modified version of the BFS operator theoretic renormalization analysis. Moreover, using a positivity argument we prove that the ground state of the spin-boson model is unique. We show that the expansion coefficients of the ground state and the ground-state energy can be calculated using regular analytic perturbation theory. Springer Basel AG, 2011 Hasler David Department of Mathematics, College of William and Mary, 23187-8795, Williamsburg, VA, USA aut Herbst Ira Department of Mathematics, University of Virginia, 22904-4137, Charlottesville, VA, USA aut Annales Henri Poincaré SP Birkhäuser Verlag Basel 12/4(2011-05-01), 621-677 1424-0637 12:4<621 2011 12 23 https://doi.org/10.1007/s00023-011-0091-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00023-011-0091-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hasler David Department of Mathematics, College of William and Mary, 23187-8795, Williamsburg, VA, USA aut NATIONALLICENCE 700 1- Herbst Ira Department of Mathematics, University of Virginia, 22904-4137, Charlottesville, VA, USA aut NATIONALLICENCE 773 0- Annales Henri Poincaré SP Birkhäuser Verlag Basel 12/4(2011-05-01), 621-677 1424-0637 12:4<621 2011 12 23 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer