change order of indices

roam/data/d6/e44fbc-975b-463d-87f9-878d50758b55/index.tex

@@ -519,13 +519,13 @@ find
 \begin{equation}
   \label{eq:39}
   \ev{{b_{\outputf}(x,t)}} =
-  \ev{b_{\inputf}(x,t)} - ∑_{σ=\pm}∫_{0}^{τ(x,t)}χ_{σ,\sgn(x)}(τ(x,t),s) \ev{b_{\inputf,σ}(s)} \dd{s}
+  \ev{b_{\inputf}(x,t)} - ∑_{σ=\pm}∫_{0}^{τ(x,t)}χ_{\sgn(x),σ}(τ(x,t),s) \ev{b_{\inputf,σ}(s)} \dd{s}
 \end{equation}
 with the time non-local susceptibility for the left and right moving
 input fields
 \begin{equation}
   \label{eq:40}
-  χ_{σ,δ}(t,s) = \frac{π n_{B}}{c}Θ(t) ∑_{γ}\pqty{U^{δ}_{γ}(t)}^\astχ_{γ}(t-s)U^{σ}_{γ}(s).
+  χ_{δ,σ}(t,s) = \frac{π n_{B}}{c}Θ(t) ∑_{γ}\pqty{U^{δ}_{γ}(t)}^\astχ_{γ}(t-s)U^{σ}_{γ}(s).
 \end{equation}
 
 For an input field with no left-moving components and a measurement