= Virasoro generator
{c}
{title2=$L_n=(2\pi i)^{-1}\oint dz\,z^{n+1}T(z)$}
<Virasoro generators> are the contour modes of the holomorphic stress tensor in a <two-dimensional conformal field theory>. Their commutators are $[L_m,L_n]=(m-n)L_{m+n}+c(m^3-m)\delta_{m+n,0}/12$. A contour around an operator insertion extracts the corresponding coefficient of its stress-tensor <operator product expansion>. $L_{-1}$ generates translations, $L_0$ measures holomorphic weight, and all positive generators annihilate a <primary state>. An independent antiholomorphic copy acts on the other weight.
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