A new era in fundamental physics Higgs: from theory to experiments André França – Baku 2013

fundamental physics Nature has different degrees of freedom at each scale. separation of scales:

fundamental physics With enough energy, we can probe shorter length scales and discover more fundamental degrees of freedom.

LHC, Geneva

standard model of particle physics

higgs discovery

What is the Higgs boson? Why did we expect the Higgs? What comes next?

quantum field theory 101 -> Particles are (quantum) excitations of a field theory. u(x,t) (classical) equations of motion: This is an example of a free wave – no potential energy and no interactions.

When a field excitation propagates, it creates disturbances in other fields. Example: A propagating electron creates a disturbance in the electromagnetic field – photon. Effects of interactions are given by a very complicated nonlinear wave equation. We use perturbation theory to compute probabilities. quantum field theory 102

If interactions are too strong: probabilities no longer add up to 1. unitarity crisis This is what happens in the standard model without the Higgs. (Also, the theory is non-renormalizable. But you don’t want to hear about that.)

H(x,t) = v + h(x,t) Vacuum expectation value Higgs boson Particles interacting with the Higgs field become massive because of its vacuum expectation value. higgs field

What is beyond the standard model? Will the LHC give us dark matter? What is dark energy? Where do neutrino masses come from? What is the quantum theory of gravity? Is there supersymmetry around the corner? open questions What is the correct model of inflation? Where are the axions? Why is the Higgs mass so small?

conclusion It’s a very exciting era for particle physics! André França, LMU Munich.