Recent content by FrancescoS

Thank you. So the keyword is "analytic continuation" If think. I will go to review, thank you again

Ok, this is the same of the first calculation I wrote. But, can you explicit the time-dependence of the field ##\Psi##. We start with a field ##\Psi(x,t)## and then we get... ?

Because it should be ## S_E = \int d\tau d^3 x \Psi^\dagger(x,\tau)(\partial_t - \frac{\nabla^2}{2m})\Psi(x,t) ## which is different from what I obtained. This is the paper (pag.7) http://arxiv.org/abs/nucl-th/0510023

And then how do you derive the euclidean action? I'm reading a paper which is following this method...

I'm working with the signature ##(+,-,-,-)## and with a Minkowski space-stime Lagrangian ## \mathcal{L}_M = \Psi^\dagger\left(i\partial_0 + \frac{\nabla^2}{2m}\right)\Psi ## The Minkowski action is ## S_M = \int dt d^3x \mathcal{L}_M ## I should obtain the Euclidean action by Wick rotation. My...

I'm studying dispersion relations applied as alternative method to perturbation theory from Weinberg's book (Vol.1) Let's consider the forward scattering in the lab frame of a massless boson of any spin on an arbitrary target ##\alpha## of mass ##m_\alpha>0## and ##\vec{p}_\alpha = 0##...

Hi guys, I'm working with this interaction Lagrangian density ##\mathcal{L}_{int} = \mathcal{L}_{int}^{(1)} + \mathcal{L}_{int}^{(2)} + {\mathcal{L}_{int}^{(2)}}^\dagger = ia\bar{\Psi}\gamma^\mu\Psi Z_\mu +ib(\phi^\dagger\partial_\mu \phi - \partial_\mu\phi^\dagger \phi)Z^\mu,## with ##...