Speaker
Description
When the Higgs effective potential $V_{eff}(\phi)$ and/or the vacuum energy $\rho$ are derived from higher dimensional theories with compact extra dimensions and non-trivial boundary conditions (as in the case of the Scherk-Schwarz SUSY breaking mechanism), the usual calculations lead to the conclusion that these quantities are UV-insensitive. Based on the finite result for $\rho$ and on the measured value of the cosmological constant, it has been recently proposed that we might live in a universe with a single compact extra dimension (dark dimension), whose mesoscopic size is of order $\mu\,m$. Since this proposal has been advanced, a lot of work has been dedicated to studying several phenomenological consequences related to the existence of this fifth (compact) dimension. We show that a source of strong UV-sensitivity for $\rho$, intimately connected to the non-trivial topology of the spacetime, is missed by the usual calculation and renders the dark dimension proposal untenable, at least the way it has been originally formulated.
