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liouville_theory [2021/06/29 22:21]
Brian McPeak [Lagrangian Picture]
liouville_theory [2021/06/29 22:36] (current)
Brian McPeak [Bootstrap Picture]
Line 100: Line 100:
  
 ===Some Remaining questions=== ===Some Remaining questions===
-  * This theory has no ground state. So how do I normalize the partition function?+  * How is the partition function normalized in a theory with no ground state?
  
 =====Lagrangian Picture===== =====Lagrangian Picture=====
Line 107: Line 107:
  
 \begin{align} \begin{align}
-    S =  \frac{1}{4 \pi} \int d^2 (\partial_a \phi \partial^a \phi + 4 \pi \mu e^{2 b \phi}+    S =  \frac{1}{4 \pi} \int d^2 (\partial_a \phi \partial^a \phi + 4 \pi \mu e^{2 b \phi} )
 \end{align} \end{align}
 +
 +$\phi$ is called the Liouville field. The equations of motion which result from this theory are 
 +
 +\begin{align}
 +  \Box \phi = - 4 \pi \mu b e^{2 b \phi}
 +\end{align}
 +
 +This is equivalent to Liouville's equation, which is the source of the theory's name. 
 +
 +It is instructive to consider the wavefunction of states which ``scatter" off the potential barrier $V(\phi)$. This takes the form
 +
 +\begin{align}
 +  \Psi_P(\phi) \sim e^{2 i P \phi} + R(P) e^{-2 i P \phi}
 +\end{align}
 +
 +Here $R(P)$ is the reflection amplitude for incoming plane-waves with momentum $P$, and may be computed from the equation of motion. The wave functions $\Psi$ describe the states which map to the Virarsoro primaries of Liouville theory under the state-operator correspondence. 
 +
 =====External Links===== =====External Links=====
   * Xi Yin's [[https://pos.sissa.it/305/003/pdf|notes]] on 2D CFTs, section 3.5   * Xi Yin's [[https://pos.sissa.it/305/003/pdf|notes]] on 2D CFTs, section 3.5