Light-front zero modes, tadpoles, and vacuum bubbles (1/2)

by Prof. J.R. Hiller, Prof. S.S. Chabysheva

Wednesday Jan 21, 2026, 9:00 PM → 11:00 PM Asia/Shanghai

Light-front zero modes are modes with zero longitudinal light-front momentum.  We consider their importance for scalar theories, particularly two-dimensional $\phi^4$ theory where there is a discrepancy between traditional light-front and equal-time calculations of the critical coupling.  The discrepancy is related to the apparent lack of tadpole contributions in light-front quantization.  We show how this lack can be rectified and how to deal with the collateral damage of (divergent) vacuum bubbles in nonperturbative calculations.  Along the way, we discover that the `trivial' light-front vacuum may be trivial only in a nontrivial way.

Zoom ID 961 0281 8089  PW 245016

https://zoom.us/j/96102818089?pwd=I9iTRAaZUOsgfg4QP0XTrxbvSbHc1a.1