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Full-Text Articles in Physical Sciences and Mathematics
Black Hole Entropy In Ads/Cft And The Schwinger-Keldysh Formalism, Luke Mrini
Black Hole Entropy In Ads/Cft And The Schwinger-Keldysh Formalism, Luke Mrini
Undergraduate Honors Theses
The Schwinger-Keldysh formalism for non-equilibrium field theory provides valuable tools for studying the black hole information loss paradox. In particular, there exists a Noether-like procedure to obtain the entropy density of a system by a discrete Kubo-Martin-Schwinger (KMS) variation of the action. Here, this Noether-like procedure is applied to the boundary action of an asymptotically anti-de Sitter (aAdS) black hole spacetime in maximally extended Kruskal coordinates. The result is the Kubo formula for shear viscosity, which is known in theories with an Einstein gravity dual to have a universal, constant ratio with the entropy density and is proportional to the …
Nonlocal Lorentz-Violating Modifications Of Qed, Qian Niu
Nonlocal Lorentz-Violating Modifications Of Qed, Qian Niu
Undergraduate Honors Theses
We consider nonlocal Lorentz-violating theories, with infinite-derivative quadratic terms. The nonlocal modifications in the form of exponential damping in the propagator lead to a better convergence of amplitudes than in the local theories. Moreover, the nonlocal Lorentz-violating theories are ghost-free and unitary when formulated in Minkowski space. We compute the loop effects assuming one-parameter and two-parameter nonlocal functions. By comparing the lower bound of the nonlocality scale with the Planck scale, we rule out these theories. We then review a more general argument, developed by Collins et al. (2004), that a microscopic theory with Lorentz violation around the Planck scale …
Composite Gravity In Curved Spacetime, Austin Batz
Composite Gravity In Curved Spacetime, Austin Batz
Undergraduate Honors Theses
This work presents the development of a quantum theory of gravity motivated by diffeomorphism-invariance and background-independence. A composite graviton state that satisfies the linearized Einstein’s field equations has been identified via perturbative expansion about a curved vacuum spacetime. The emergence of this gravitational interaction is discussed, as well as cancellation of tadpoles and treatment of ultraviolet divergences via dimensional regularization. In other words, the formalism of quantum field theory is used to identify a gravitational interaction as an emergent phenomenon rather than as a fundamental aspect of nature. The lattice is proposed as a candidate for a physical regulator, and …