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phd-thesis/sec/app/reflection.tex
2020-09-29 18:48:42 +02:00

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We provide details on how~\eqref{eq:reflection condition_out_field_generic_vacuum} can be computed.
First we introduce the projector of positive frequency and negative frequency modes for the NS fermion as
\begin{eqnarray}
P^{(+,\, 0)}(z,w)
& = &
\frac{+1}{z-w},
\qquad
\abs{z} > \abs{w}
\\
P^{(-,\, 0)}(z,w)
& = &
\frac{-1}{z-w},
\qquad
\abs{z} < \abs{w},
\end{eqnarray}
such that
\begin{equation}
\oint\limits_{\abs{z} > \abs{w}} \ddw
P^{(+,\, 0)}(z,w)\,
\Psi^{(0)}( 0 )
=
\Psi^{(0,\, +)}( z ),
\end{equation}
and similarly for the negative frequency modes.
Likewise we introduce the projectors for the field with defects as
\begin{eqnarray}
P^{(+)}(z,\, w)
& = &
\frac{P\qty(z;\, \qty{x_{(t)},\, \rE_{(t)}} )\,
P\qty(w;\, \qty{x_{(t)},\, -\rE_{(t)}} )
}{z-w},
\qquad
\abs{z} > \abs{w}
\\
P^{(-)}(z,\, w)
& = &
-
\frac{P\qty(z;\, \qty{x_{(t)},\, \rE_{(t)}} )\,
P\qty(w;\, \qty{x_{(t)}, -\rE_{(t)}} )
}{z-w},
\qquad
\abs{z} < \abs{w},
\end{eqnarray}
with $P\qty(z;\, \qty{x_{(t)},\, \rE_{(t)}} ) = \finiteprod{t}{1}{N} \qty( 1- \frac{z}{x_{(t)}} )^{\rE_{(t)}}$ as in the main text.
We then compute
\begin{equation}
\begin{split}
\qty(P^{(+)}\, P^{(+,\,0)})(z,\, w)
& =
\oint\limits_{\abs{z} > \abs{\zeta} > \abs{w}} \ddz
P^{(+)}(z,\, \zeta)\,
P^{(+,\, 0)}(\zeta,\, w)
=
P^{(+,\, 0)}(z,\, w)
\\
\qty(P^{(+)}\, P^{(-,\, 0)})(z,\, w)
& =
\frac{P\qty(z;\, \qty{x_{(t)},\, \rE_{(t)}} )\,
P\qty(w;\, \qty{x_{(t)},\, -\rE_{(t)}} ) -1
}{z-w}.
\end{split}
\end{equation}
The last equation is valid when $\rM=\finitesum{t}{1}{N} \rE_{(t)} \le 0$ and for $\abs{z}$ and $\abs{w}$ arbitrary.
Specializing the previous expressions to $\Psi^{(out)}( z )$, we need to constrain $\abs{z} > x_{(1)}$ and $\abs{w} > x_{(1)}$.
Finally the vacuum in presence of defects can be described by
\begin{equation}
\begin{split}
\Psi^{(+)}( z ) \Gexcvacket
& =
\qty(P^{(+)}\, \Psi)( z ) \Gexcvacket
\\
& =
\qty(P^{(+)}\, \Psi^{(out)})( z ) \Gexcvacket
\\
& =
\left\lbrace
\qty(P^{(+)}\, P^{(+,\, 0)}\, \Psi^{(out)})( z )
\right.
\\
& +
\left.
\qty(P^{(+)}\, P^{(-,\, 0)}\, \Psi^{(out)})( z )
\right\rbrace
\Gexcvacket
\\
& =
0,
\end{split}
\end{equation}
where we assumed $\abs{z} > x_{(1)}$.
The expression finally becomes~\eqref{eq:reflection condition_out_field_generic_vacuum}.
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