A stochastic Dyson series expansion

Author(s):  
K. R. Parthasarathy ◽  
K. B. Sinha

2021 ◽  
Author(s):  
Erickson Tjoa

We present a straightforward implementation of contour integration by setting options for Integrate and NIntegrate, taking advantage of powerful results in complex analysis. As such, this article can be viewed as documentation to perform numerical contour integration with the existing built-in tools. We provide examples of how this method can be used when integrating analytically and numerically some commonly used distributions, such as Wightman functions in quantum field theory. We also provide an approximating technique when time-ordering is involved, a commonly encountered scenario in quantum field theory for computing second-order terms in Dyson series expansion and Feynman propagators. We believe our implementation will be useful for more general calculations involving advanced or retarded Green’s functions, propagators, kernels and so on.





Author(s):  
Marco Merkli ◽  
Alireza Rafiyi

We consider a large number N of quantum particles coupled via a mean field interaction to another quantum system (reservoir). Our main result is an expansion for the averages of observables, both of the particles and of the reservoir, in inverse powers of N . The analysis is based directly on the Dyson series expansion of the propagator. We analyse the dynamics, in the limit N → ∞ , of observables of a fixed number n of particles, of extensive particle observables and their fluctuations, as well as of reservoir observables. We illustrate our results on the infinite mode Dicke model and on various energy-conserving models.



Author(s):  
Jaan Oitmaa ◽  
Chris Hamer ◽  
Weihong Zheng




Author(s):  
Antonio Carlos Foltran ◽  
Carlos Henrique Marchi ◽  
Luís Mauro Moura


2015 ◽  
Vol 18 (2) ◽  
pp. 149-156
Author(s):  
Shawki A.M. Abbas ◽  
Keyword(s):  


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