$d=4$ as the critical dimensionality of asymptotically safe interactions

Understand

We explore the question why our universe is four dimensional from an asymptotically safe vantage point.

• We find hints that asymptotically safe quantum fluctuations of gravity can only solve the $U(1)$ Landau-pole problem in the Standard Model in four dimensions.
• This could single out the observed dimensionality of the universe as the critical dimensionality of asymptotically safe interactions.