## Von Neumann algebras in field theory

##### Author(s)

Rajagopal, Srivatsan,Ph. D.Massachusetts Institute of Technology.
Download1133645685-MIT.pdf (7.425Mb)

##### Other Contributors

Massachusetts Institute of Technology. Department of Physics.

##### Advisor

Hong Liu.

##### Terms of use

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Show full item record##### Abstract

In this thesis, I show that modular flows of generic excited states in a quantum field theory can be studied by restricting attention to a special class of states whose associated modular flow can be characterised easily; this follows from a certain theorem involving the invertible group of operators in a general von Neumann algebra, namely that such operators are a dense subset of the algebra in the strong operator topology. I also develop tools to compute these flows using a novel perturbation expansion : the structure of the terms appearing in the expansion is made manifest to all orders in the expansion. Finally, I write down an effective action for a general charged fluid which has an anomalously broken symmetry; the novelty here is that this effective action is local (previous treatments gave a non-local effective action for such a fluid). This construction also gives a simple explanation for various puzzling coincidences which have been reported in the literature before.

##### Description

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2019 Cataloged from PDF version of thesis. Includes bibliographical references (pages 169-171).

##### Date issued

2019##### Department

Massachusetts Institute of Technology. Department of Physics##### Publisher

Massachusetts Institute of Technology

##### Keywords

Physics.