Hello. Standard Model is based on the lagrangian of the dirac equation where some gauge group are applied. But, i am asking me, why a field is used before it was created. Properties of particle come from the application of Noether Théorem and then a quantization. I imagine the same process for the creation of the field. In my mind i expect that matter fields are conseved quantities in a bigger manifold and the quantization produce quantum field theory ? My question is : do you know the origin of matter field ? Or a paper speaking about ? I read Michele Maggiore book (A Modern introduction to QFT) and recent papers without finding any answer. Thanks a lot Clément.