Year: 2025
Type: dissertation
Abstract: In this thesis, we explore both the classical and quantum consequences of Weyl symmetry in the contexts of Riemannian and non-Riemannian geometries.In particular, we delve into classical Weyl-invariant theories in a metric-affine setting and examine the arguably most significant quantum phenomenon associated with this symmetry: the conformal anomaly.Indeed, in the context of quantum fields on curved backgrounds, the conformal anomaly plays a crucial role in studying the renormalized generating functional for one-particle irreducible correlation functions.This work presents some new results related to these topics.We complete the classification of conformal actions for all the tensors species within a general metric-affine framework, and investigate the physical implications of relaxing the requirement of full Weyl invariance by considering some substructures of the Weyl group in a Riemannian setting.Among other results, these substructures reveal an intriguing connection between conformal and higherderivative gravity, where the latter can be viewed as a partially gauge-fixed version of the former.On the quantum side, we systematize the use of the ambient space formalism to construct and integrate the conformal anomaly in each even dimension considering scenarios where the metric is the only background field.Additionally, we propose an extension of the concept of anomaly to the aforementioned Weyl subgroups, and employ cohomological methods to derive the most general trace anomalies and anomalous actions in the presence of torsion in d = 2, 4 in a completely model-independent way.i This journey has been an extraordinary experience of personal and professional growth.I am very grateful to my supervisor Omar Zanusso for his constant guidance while still granting me both the necessary independence to improve as a physicist and the freedom to explore the topics I was most passionate about.I also want to thank him for introducing me to those two unforgettable characters-the guy with the torn-up karategi and a fierce passion for brawling, and the strawberry-loving girl who was so determined to conquer an impossible mountain.I would also like to express my heartfelt gratitude to the entire Ph.D. crew, especially Dario, Berio, Giovanni, Fra Bert, Peppe Clemente, Lorenzo, and my office mate Matteo, for the big laughs, innumerable pints, encouragement, gaming and music sessions.You have been like family to me.A special thank you goes to the Bibi, aka Silvia, for always being there for me, even during the toughest moments, for reminding me that life is not only about work, and for the countless wonderful moments we've shared.Thank you for being the way you are.Finally, I want to extend my deepest thanks to my family and
Author: PACI, GREGORIO
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7009917126