## The Standard Model Lagrangian

If you're wondering about the equation in the banner, it is the Lagrangian of the standard model. It is the most succinct way of writing the laws governing the strong, electromagnetic and weak forces and their interaction with the known particles. The origin of this hand written version originates at CERN, but

curiously enough, it accidentally writes the 2nd term twice. This is because the h.c. (= Hermitian conjugate) of the 2nd term is the 2nd term itself, since it is self conjugate, as pointed out here.

The figure plots the potential of two components of the Higgs field $\phi$ (since it is an SU(2) doublet it has 2 complex components, i.e., 4 real numbers, but 2 are plotted for simplicity!). The spontaneous breaking of the Higgs field gives this "mexican hat" looking potential. The excitations around a point (the new vacuum) in the "valley" along the hat gives particles with masses (and a massless particle).

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