Kenichi Konishi will cover both Part I and Part II from 10:30am – 12:30pm.
Part I: Anomalies, dynamics and phases in strongly-coupled chiral gauge theories: recent developments
After many years of efforts, still very little is known today about the physics of strongly-coupled chiral gauge theories in four dimensions, in spite of an important role they might play in the physics of fundamental interactions beyond the standard SU(3)xSU(2)xU(1) model. This is in stark contrast with the vectorlike gauge theories for which we have many solid results, thanks to some exact theorems, to the lattice simulation studies, to the Seiberg-Witten exact solution of N=2 supersymmetric gauge theories, and last, but not the least, to the real-world strong-interaction phenomenology and experimental tests of Quantum Chromodynamics.
The purpose of this seminar is to discuss the results of our recent efforts to improve the understanding of the strongly-coupled chiral gauge theories. Among the main tools of analysis are the consideration of anomalies. We use both the conventional ’t Hooft anomaly-matching ideas, and new, more stringent constraints coming from the generalized anomalies involving some higher-form symmetries. Also, the so-called strong anomalies, little considered in the context of chiral gage theories, are found to carry significant implications.
As the playground we study several classes of SU(N) gauge theories, the so-called Bars-Yankielowicz models, the generalized Georgi-Glashow models, as well as a few other simple theories with the fermions in complex, anomaly-free representations of the color SU(N).
Color-flavor-locked dynamical Higgs phase and dynamical Abelianization, emerge, among others, as two particularly interesting possible phases the system can flow into in the infrared, depending on the matter fermion content of the model.
Part II: Quantum fluctuations, particles and entanglements: towards the solution of the Quantum Measurement Problem
The quantum measurement problems are revisited from a new perspective. One of the main ideas of this work is that the basic entities of our world are various types of particles, elementary or composite. It follows that each elementary process, hence each measurement process at its core, is a spacetime, pointlike, event.
Another key idea is that, when a microsystem $\psi$ gets into contact with the experimental device, factorization of $\psi$ rapidly fails and entangled mixed states appear.
The wave functions for the microsystem-apparatus coupled systems for different measurement outcomes then lack overlapping spacetime support. It means that the aftermath of each measurement is a single term in the sum: the fact sometimes perceived as the “wave-function collapse”.
Our discussion leading to a diagonal density matrix shows how the information encoded in the wave function gets transcribed, via entanglement with the experimental device and environment, into the relative frequencies for various experimental results.
These results represent new, significant steps towards filling in the logical gaps in the standard interpretation based on Born’s rule, replacing it with a more natural one. Accepting objective reality of quantum fluctuations, independent of any experiments, and independently of human presence, one renounces for good the idea that in a fundamental, complete theory of Nature the result of each single experiment must necessarily be predictable.
A few well-known puzzles such as the Schr\”odinger cat conundrum and the EPR paradox will be briefly revisited: they can all be naturally explained away.
For more information on how to join, please see: https://cmsa.fas.harvard.edu/quantum-matter-seminar/