Slides for lectures 3 and 4 December 5, 2007Posted by dorigo in internet, news, personal, physics, science.
I completed the discussion on the Higgs sector of the Standard Model in my lectures of last Monday and Tuesday (the slides for the previous two lectures are here – and to know what I am talking about see here). In this segment of the course, I discussed Higgs boson phenomenology and its searches at colliders (LEP II, Tevatron, LHC). The slides for Lectures III and IV are here.
Maybe the most interesting part of the lectures is when a detailed explanation is provided of the behavior of the Higgs decay branching fractions seen as a function of the unknown mass of the Higgs. This is always useful because it provides insight in the theoretical structure of the model – by allowing a free parameter to vary you are in fact examining a continuous infinity of different phenomenological situations. In the slides this is only partly apparent – I used the blackboard a lot.
I then gave a rather quick and dirty overview of the LEP II limit, and then went on to consider hadron collider phenomenology in short, before discussing the searches ongoing at the Tevatron (in WH,ZH,WW final states) and the future searches at the LHC.
I spent most of the time discussing what one expects to see from these experimental signatures, when one considers all the mess one has to live with when colliding those subatomic bags of garbage – protons, that is. Actually, gazillions of bags of garbage every second! At LHC, at design luminosity, we expect to be producing about a billion proton collisions every second inside the CMS and Atlas detectors! That is simply mindboggling if you think that each 14-TeV collision may generate hundreds of primary particles in the detector – each of which will convert to electronic pulses after converting into a few thousand more).
Since I wrote the last sentence and found it interesting to convert the image into another macroscopic figure: as far as energy goes, the total energy which is subtracted from the beam by proton-proton scattering at LHC is a billion TeV per second. That means 10 to the 21st power electronvolts, or roughly 60 Joules per second, or 60 watts. You can illuminate a room with the energy of those protons! Maybe not a grand concept if you were expecting kinetic energies of Jumbo jets (as is the total energy in the LHC beams), but still something worth keeping in mind.