"Volume of a compact Lie group"의 두 판 사이의 차이

수학노트
둘러보기로 가기 검색하러 가기
imported>Pythagoras0
imported>Pythagoras0
1번째 줄: 1번째 줄:
 +
==introduction==
 +
* Define $J_\lambda(x)=  h(\lambda)^{-1}\det(e^{\lambda_i x_j})$, where $ h(\lambda)=\prod_{i<j}(\lambda_i-\lambda_j)$. 
 +
* For each $x$, $J_\lambda(x)$ is an analytic function of $\lambda$; in particular, $J_0(x)=\left(\prod_{j=1}^{n-1} j!\right)  h(x)$.
 +
* The functions $J_\lambda(x)$ play a central role in random matrix theory.
 +
* For example, if $\Lambda$ and $X$ are Hermitian matrices with eigenvalues given by $\lambda$ and $x$, respectively, then
 +
\begin{equation}\label{iz}
 +
\int_{U(n)}e^{\rm tr \Lambda U X U^*} dU=\frac{J_\lambda(x)}{J_0(x)},
 +
\end{equation}
 +
where the integral is with respect to normalised Haar measure on the unitary group.
 +
* This is known as the Harish-Chandra, or Itzykson-Zuber, formula.
 +
 +
 
==related items==
 
==related items==
 
* [[Random matrix]]
 
* [[Random matrix]]

2016년 1월 1일 (금) 05:43 판

introduction

  • Define $J_\lambda(x)= h(\lambda)^{-1}\det(e^{\lambda_i x_j})$, where $ h(\lambda)=\prod_{i<j}(\lambda_i-\lambda_j)$.
  • For each $x$, $J_\lambda(x)$ is an analytic function of $\lambda$; in particular, $J_0(x)=\left(\prod_{j=1}^{n-1} j!\right) h(x)$.
  • The functions $J_\lambda(x)$ play a central role in random matrix theory.
  • For example, if $\Lambda$ and $X$ are Hermitian matrices with eigenvalues given by $\lambda$ and $x$, respectively, then

\begin{equation}\label{iz} \int_{U(n)}e^{\rm tr \Lambda U X U^*} dU=\frac{J_\lambda(x)}{J_0(x)}, \end{equation} where the integral is with respect to normalised Haar measure on the unitary group.

  • This is known as the Harish-Chandra, or Itzykson-Zuber, formula.


related items


expositions

articles

  • Shu, Fu-Wen, and You-Gen Shen. “Several Integrals of Quaternionic Field on Hyperbolic Matrix Space.” arXiv:1511.01385 [gr-Qc, Physics:math-Ph], November 4, 2015. http://arxiv.org/abs/1511.01385.
  • Hashimoto, Y. “On Macdonald’s Formula for the Volume of a Compact Lie Group.” Commentarii Mathematici Helvetici 72, no. 4 (April 3, 2014): 660–62. doi:10.1007/s000140050040.
  • Macdonald, I. G. “The Volume of a Compact Lie Group.” Inventiones Mathematicae 56, no. 2 (February 1980): 93–95. doi:10.1007/BF01392542.
  • Itzykson, C., and J. B. Zuber. “The Planar Approximation. II.” Journal of Mathematical Physics 21, no. 3 (1980): 411–21. doi:10.1063/1.524438.