A new era in fundamental physics Higgs from

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

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

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. (classical) equations of motion: u(x, t) This is an example of a free wave – no potential energy and no interactions.

quantum field theory 102 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.

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

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

open questions What is beyond the standard model? Why is the Higgs mass so small? 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? What is the correct model of inflation? Where are the axions?

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