Finite-Temperature Form Factors: a Review

• Main Author: Benjamin Doyon
• Format: Article
• Language: English
• Published: National Academy of Science of Ukraine 2007-01-01
• Series: Symmetry, Integrability and Geometry: Methods and Applications
• Subjects: finite temperature; integrable quantum field theory; form factors; Ising model
• Online Access: http://www.emis.de/journals/SIGMA/2007/011/

We review the concept of finite-temperature form factor that was introduced recently by the author in the context of the Majorana theory. Finite-temperature form factors can be used to obtain spectral decompositions of finite-temperature correlation functions in a way that mimics the form-factor expansion of the zero temperature case. We develop the concept in the general factorised scattering set-up of integrable quantum field theory, list certain expected properties and present the full construction in the case of the massive Majorana theory, including how it can be applied to the calculation of correlation functions in the quantum Ising model. In particular, we include the ''twisted construction'', which was not developed before and which is essential for the application to the quantum Ising model.