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Physics Colloquium: Mohamed Anber

Date: 4:15pm PST January 27 Location: Olin 204

Olin 204

Please join us at 4:00 pm in the Olin lobby for cookies and conversation.

Title: Deconfinement on Axion Domain Walls

Abstract: The general lore, according to effective field theory, is that one ignores the high energy degrees of freedom when studying low energy phenomena. For example, and as a matter of fact, we do not need to understand quantum chromodynamics (QCD) (the strong nuclear force) to understand fluid mechanics! However, the existence of ‘t Hooft anomalies (subtle phases in the partition function) may signal a non-trivial intertwining between the high and low energy scales. This nontrivial assertion can be seen in axion physics;axion is a hypothetical particle that may play important roles in solving a few puzzles in the Universe.After a brief introduction to QCD and axions, I show how this intertwining takes place on axion domain walls (a domain wall (DW) is the boundary between two neighboring domains). To this end, I first discuss a new class of ‘t Hooft anomalies that I recently identified, and then use the anomalies to argue that quarks are deconfined (liberated) on axion DW. This newly discovered phenomenon implies that a non-trivial interplay between different scales happens on the walls. Further, I confirm this picture by performing explicit calculations in a toy model, which is argued to be continuously connected to the full-fledged QCD.