View source for Talk:Quantum field theory

==Definition of $ {\rho_{\kappa}}(\Box) $==

Could someone please explain the meaning of $ {\rho_{\kappa}}(\Box) $, which occurs two displayed equations below Equation (6)? I checked the published version of Encyclopedia of Mathematics to see if the expression appears there as well, and indeed it does. However, no definition is given.

:Probably, the function $\rho_{\kappa}$ applied to the d'Alembertian $\Box$. In the formula for the smoothing function $D_{\kappa,\epsilon}$ we see $\rho_{\kappa}(\langle p,p \rangle)$; and this Fourier transform diagonalizes $\Box$, turning it into multiplication by $p\mapsto\langle p,p \rangle$, right? [[User:Boris Tsirelson|Boris Tsirelson]] ([[User talk:Boris Tsirelson|talk]]) 16:15, 5 December 2016 (CET)