Add a new page:
This is an old revision of the document!
The scalar model in 1 spatial and 1 time dimension is the simplest quantum field theory we can study. It is often used to introduce the basics of solitonic solutions, since the Scalar 1+1 models contains a kink solution.
The model only contains a real scalar field $\phi (x) \in \mathbb{R}$. The scalar potential is
$$ U= \frac{\lambda}{2} ( \phi^2-a^2)^2, $$
and is conveniently normalized such that the ground state (the vacuum solution) is at $U=0$. In addition, the potential is bounded from below $U\geq 0$.
The field equation is
$$ \partial_{x_i}^2 \phi = 2 \lambda \phi (\phi^2-a^2). $$
It is important to note that this field equation is a non-linear differential equation and hence allows non-linear solutions.
Solitonic Solutions - The Kink