Quantum Fields from Casual Order

Mathur, Abhishek

Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/8054

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DC Field	Value	Language
dc.contributor.advisor	Surya, Sumati	-
dc.contributor.author	Mathur, Abhishek	-
dc.date.accessioned	2023-03-01T06:00:59Z	-
dc.date.available	2023-03-01T06:00:59Z	-
dc.date.issued	2023-02	-
dc.identifier.citation	Ph.D. Thesis, Jawaharlal Nehru University, New Delhi, 2023	en_US
dc.identifier.uri	http://hdl.handle.net/2289/8054	-
dc.description	Restricted Access	en_US
dc.description.abstract	Quantum Field Theory (QFT) in curved spacetime describes physical phenomena in a regime where quantum fields interact with the classical gravitational field. These conditions are generally satisfied either in the vicinity of a black hole or in the post Planckian very early universe. The standard approach to QFT relies heavily on the Poincare symmetry of Minkowski spacetime as a guide to a particular choice of mode expansion and therefore a preferred choice of vacuum. In contrast, in a generic curved spacetime which does not have any symmetry, the choice of mode expansion and hence the vacuum is arbitrary. This suggests that the notion of vacuum and particles is subsidiary. This is the approach taken in algebraic QFT (AQFT), where the primary role is played by the algebra of observables and the choice of state, which is primarily defined as a complex function on this algebra, is relegated to a choice of the representation of this algebra, and is therefore not unique. It is natural to ask if there exists an alternative formulation of the QFT vacuum which is inherently covariant. One such formalism was developed by Sorkin [1] and Johnston [2] called the Sorkin-Johnston (SJ) vacuum. In this thesis we will explore various aspects of the SJ vacuum both in the continuumand in the causal set theory. QFT also plays an important role in understanding the entropy of black holes and other horizons. Entanglement entropy of quantum fields has been proposed as a candidate for these entropies. The standard formulation of the entanglement entropy is given by the von Neumann entropy formula, which requires the QFT states to be defined on a Cauchy hypersurface and is therefore dependent on the choice of the hypersurface. Sorkin, in his 2014 paper [3], proposed a spacetime formulation of the entanglement entropy, which is covariant.	en_US
dc.language.iso	en	en_US
dc.publisher	Raman Research Institute	en_US
dc.rights	This thesis is posted here with the permission of the author. Personal use of this material is permitted. Any other use requires prior permission of the author. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.	en_US
dc.subject.classification	Theoretical Physics	-
dc.title	Quantum Fields from Casual Order	en_US
dc.type	Thesis	en_US
Appears in Collections:	Theses (TP)

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