2015/04/20 by Pablo Schad, P. Schad, Yu. Makhlin +5
Chemistry · Physics and Astronomy · #Advanced Condensed Matter Physics #Advanced NMR Techniques and Applications #Correlation function (quantum field theory) #Fermion #MAJORANA #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Saddle point #Spin (aerodynamics) #cond-mat.mes-hall #cond-mat.str-el
paper · pdf · doi:10.1016/j.aop.2015.07.006
published as Annals of Physics 361, 401 (2015) · 20 pages, 6 figures
arxiv created 2015/04/20 · openalex publication_date 2015/07/15 · arxiv updated 2015/08/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The Majorana representation of spin operators allows for efficient field-theoretical description of spin-spin correlation functions. Any N-point spin correlation function is equivalent to a 2N-point correlator of Majorana fermions. For a certain class of N-point spin correlation functions (including "auto" and "pair-wise" correlations) a further simplification is possible, as they can be reduced to N-point Majorana correlators. As a specific example we study the Bose-Kondo model. We develop a path-integral technique and obtain the spin relaxation rate from a saddle point solution of the theory. Furthermore, we show that fluctuations around the saddle point do not affect the correlation functions as long as the latter involve only a single spin projection. For illustration we calculate the 4-point spin correlation function corresponding to the noise of susceptibility.