Sigma Theta Tau

{\displaystyle \sigma _{\mathrm {n} }={\frac {1}{2}}(\sigma _{x}+\sigma _{y})+{\frac {1}{2}}(\sigma _{x}-\sigma _{y})\cos 2\theta +\tau _{xy}\sin 2\theta } τ n

Sigma Rho, founded 000000001906-04-13-00001906年4月13日 and Tau Kappa Alpha, founded 000000001908-05-13-00001908年5月13日. Merged with Tau Beta Pi（英语：Tau Beta

{dS_{\sigma }}{d\sigma }}\right)^{2}+\left({\frac {dS_{\tau }}{d\tau }}\right)^{2}+2mU_{\sigma }(\sigma )+2mU_{\tau }(\tau )=2m\left(\sigma ^{2}+\tau

ϕ ) {\displaystyle (\sigma ,\ \tau ,\ \phi )} ： σ = cosh ⁡ μ {\displaystyle \sigma =\cosh \mu } 、 τ = cos ⁡ ν {\displaystyle \tau =\cos \nu } 、 ϕ = ϕ {\displaystyle

{\begin{array}{ll}2=\sigma (2)=\sigma (\theta ^{3})=\left(\sigma (\theta )\right)^{3},\\1=\sigma (1)=\sigma (\omega ^{3})=\left(\sigma (\omega )\right)^{3}