Center for Theoretical Physics of the Universe (CTPU-CGA)
# Colloquium: Naturalness and the Hierarchy Problems

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Asia/Seoul

438 (Theory Building)
### 438

#### Theory Building

Description

Nature contains several seemingly independent mass scales which are fixed by different types of experiments and interactions. The smallest of them is associated with the accelerated expansion of the Universe which can explained by the vacuum energy $(\epsilon_V)^{\frac{1}{4}}\sim 2.26\times 10^{-3}$ eV. The next one is the QCD confinement scale, establishing the typical size of hadrons, $\Lambda_{QCD} \sim 100$ MeV. The Fermi scale is related to the mass of the weak intermediate vector bosons, $M_W \sim 100$ GeV. The largest scale is associated with the strength of the gravitational interactions given by the Planck mass $M_P\sim 10^{19}$ GeV. I will discuss whether the multitude of these scales scattered by many orders of magnitude implies the existence of new particles and forces yet to be discovered. I will also describe the attempts to find a connection between the Fermi and Planck mass scales.