Speaker
Description
The CPT-Symmetric Universe model provides elegant solutions to major cosmological puzzles—including dark matter, the cosmological constant problem, and the universe's flatness puzzle—by positing that the Big Bang acts as a CPT mirror. However, the theoretical reason why the universe requires this mirror has remained an open question.
In this talk, we propose that the answer lies in the geometric nature of fermions. We investigate K"ahler-Dirac (KD) fermions: polyform generalizations of Dirac spinors. When quantized in Lorentzian signature, half of the KD fields naively exhibit a "wrong sign" Lagrangian, implying unphysical negative-norm states. We resolve this by proposing that these fields reside on a PT-reversed spacetime sheet. Since time flows backward on this sheet, these states naturally carry negative energy from our perspective.
To preserve causality and prevent unphysical interactions between the sheets, we impose a novel "KD-Majorana condition." This ensures every particle on the forward-time sheet is intrinsically paired with an anti-particle on the backward-time sheet. We demonstrate how this framework provides a new geometric perspective on the Standard Model: a single SM generation exactly maps onto four KD-Majorana fields, naturally reproducing Pati-Salam unification and consolidating all SM Yukawa couplings into a single unified term.
Finally, we discuss its physical implication. The KD-Majorana pairing provides the microscopic origin for the CPT-symmetric Big Bang, and offers novel insights into black hole horizons ("black mirrors"). We conclude by outlining future directions, including anomaly-free chiral lattice gauge theories and incorporating KD fermions within superstring theory.