Deconfined Quantum Criticality among Grand Unified Theories

This article overviews the recent developments in applying the idea of deconfined quantum criticality in condensed matter physics to understand quantum phase transitions among grand unified theories in high energy physics in the 4-dimensional spacetime. In particular, dictated by a mod 2 class nonperturbative global mixed gauge-gravitational anomaly, there can be a gapless deconfined quantum critical region between Georgi-Glashow and Pati-Salam models — not only the Standard Model occurs as a neighbor phase, but also beyond the Standard Model phenomena (such as deconfined dark gauge force and fractionalized/fragmentary fermionic partons) emerge near the critical region. An invited contribution to Professor Chen-Ning Yang Centenary Festschrift.