The paper by Peskin and Takeuchi reviews the analysis of electroweak vacuum polarization diagrams and their impact on precision experiments. The authors introduce a three-parameter representation—$S$, $T$, and $U”—to describe these corrections, which are crucial for understanding the Higgs sector's properties. They discuss the assumptions underlying this reduction and explore how these parameters are influenced by various models of new physics, particularly technicolor models. The paper highlights the importance of the parameter $S$, which can be estimated using dispersion relations, and discusses its reliability and gauge invariance. The authors also present experimental constraints on $S$ and $T$, showing that current data already place strong limits on these parameters. They conclude by emphasizing the significance of these constraints in distinguishing between different models of the Higgs sector and testing the fundamental idea of technicolor.The paper by Peskin and Takeuchi reviews the analysis of electroweak vacuum polarization diagrams and their impact on precision experiments. The authors introduce a three-parameter representation—$S$, $T$, and $U”—to describe these corrections, which are crucial for understanding the Higgs sector's properties. They discuss the assumptions underlying this reduction and explore how these parameters are influenced by various models of new physics, particularly technicolor models. The paper highlights the importance of the parameter $S$, which can be estimated using dispersion relations, and discusses its reliability and gauge invariance. The authors also present experimental constraints on $S$ and $T$, showing that current data already place strong limits on these parameters. They conclude by emphasizing the significance of these constraints in distinguishing between different models of the Higgs sector and testing the fundamental idea of technicolor.