QED2 and Massive Thirring Model in Infinite Momentum Frame

Abstract

We calculate the spectrum of the charge zero sector in two-dimensional field theories (the massive Schwinger model and the massive Thirring model), employing the infinite momentum frame technique (or 1/K expansion method). We first explain the 1/K expansion method which can clarify the connection between equal time and light cone quantizations. We apply it to the massive Schwinger model and confirm that it gives indeed the same equation as light cone quantization. We present some calculations of the massive Schwinger model including four fermion components (qqqq. We show that the lowest state is exactly evaluated by the qq Fock space. Then we apply it to the massive Thirring model. The eigenvalue equation for the massive Thirring model with qq Fock space is solved analytically. It is shown that the eigenvalue equation has right behaviors both for the weak and the strong coupling regions. Further, we show that the interaction between qq bosons is repulsive and therefore there is no bound state in the four fermion (qqqq) Fock space. This confirms that there is only one bound state in the massive Thirring model.