# Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Particles in the hot, early Universe.

## Presentation on theme: "Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Particles in the hot, early Universe."— Presentation transcript:

Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Particles in the hot, early Universe.

Particles This lecture: Particles in the hot early universe

The standard model of particle physics Leptons –electron q=-1 m=0.5 MeV –e-neutrino q=0 m<15 eV –muon q=-1 m=0.1 GeV – neutrino q=0 m<0.17 MeV –tau q=-1 m=1.8 GeV –tau-neutrino q=0 m<24 MeV

The standard model of particle physics Quarks –up q=2/3 m=6 MeV –down q=-1/3 m=10 MeV –strange q=-1/3 m=0.25 GeV –charm q=2/3 m=1.2 GeV –bottom q=-1/3 m=4.3 GeV –top q=2/3 m=180 GeV

The standard model of particle physics Vector bosons –photon q=0 m=0 –W boson q=+-1 m=80.3 GeV –Z boson q=0 m=91.2 GeV –gluon q=0 m=0

The standard model of particle physics Higgs boson –Higgs q=0 m < 1 TeV

Quarks Quarks are fundamental particles which may be the building blocks of all the hadrons. They have fractional charge 1/3 or 2/3 of the electronic charge 3 quarks make a proton, antiproton or neutron.

Free quarks Quarks are only created at very high energies. At 10 13 K (10 9 eV) quark-antiquark pairs are created and annihilated just like electrons and positrons at 10 6 eV. When the temperature drops, quark- antiquark pairs annihilate, but the photons dont have enough energy to make quark-antiquark pairs anymore.

Then the quarks combine to make stable baryons –quarks are effectively forbidden in coloured combinations –colour is a quantum number of quarks, like spin in electrons. There are now virtually no free quarks –but the only way to destroy a quark is to annihilate it with an antiquark or combine it with other quarks - there could be a small number of free quarks hanging around with nowhere to go, relics of the primordial soup.

Download ppt "Cosmology and extragalactic astronomy Mat Page Mullard Space Science Lab, UCL Particles in the hot, early Universe."

Similar presentations