The hierarchy, fine tuning, and naturalness problem from a philosophical perspective

本研究的目的是分析自然性原则的概念起源，并评估其在理论建构中作为指导原则的地位。由于自然原则可以被理解为对简单性的要求，它与研究单元的总体主题密切相关。在第一阶段，A2项目已经确定了自然性原理的动机中的几个弱点，并对其所谓的成功应用提出了质疑，例如对粲夸克质量的预测。在第二阶段，我们将分析物理学家对自然性概念的态度在LHC缺乏任何决定性迹象的情况下发生了多大程度和何种形式的变化。我们还打算更深入地探索自然性与重整化理论基础的联系以及还原和涌现问题，并考虑自然性在物理学其他领域的应用，包括宇宙学常数问题和强CP问题。

The goal of this project is to analyze the conceptual origins of the naturalness principle and assess its status as a guiding principle in the construction of theories. Since the naturalness principle can be understood as a demand for simplicity, it connects closely with the overarching theme of the Research Unit. In Phase 1, the A2 project has identified several points of weakness in the motivations for the naturalness principle and called into question its purported successful applications, such as the prediction of the charm quark mass. In Phase 2, we are going to analyze to what extent and in which form the attitude of physicists towards the naturalness concept has changed in the light of the lack of any conclusive signs for New Physics at the LHC. We further intend to more deeply explore the connection of naturalness to the foundations of renormalization theory and issues of reduction and emergence, and to consider applications of naturalness in other areas of physics, including the cosmological constant problem and the strong-CP problem.