Hi all, I am new to the forum. I have a BS in Chemistry (1984). So I remember a little quantum mechanics. I am trying to wrap my head around cosmology. I started studying GR on my own about a year ago. It took me almost that long to understand tensors. This invariably lead me to start reading Cosmological Physics by Peacock. Admittedly he is way over my head, but I am learning what I don't know. I am struggling with certain concepts that are required to understand the SM. I have a weak understanding of gauge symmetries, symmetry breaking ,the Dirac gamma matrices, and a some other issues with notation and such. I have looked for some introductory material on the web, but everything starts out with the very concepts I am struggling with. Can anybody recommend a truly introductory pdf that explains these things in a little more detail? TIA for any help..