The Higgs boson and Higgs field

2. Introduction • film fragment about the Higgs boson and Higgs field, by DrPhysicsA on a YouTube channel, 27th of February 2012 • topic of the new curriculum of physics in 2014-2015 • very up-to-date topic

3. • at the time the film fragment was uploaded on YouTube, the Higgs boson and Higgs field were predicted but had not yet been found • on 4 July 2012 Cern communicated the detection of the Higgs particle

4. Fields: temperature field • measure with a thermometer the temperature at every single point in a room • make a list of all this separate temperatures • this list represents the temperature field • the field causes an ice cube that is introduced in it, to melt

5. Fields: electric field • install an electric field between two opposite charged plates • put an electron in it: the electron starts to move by the interaction with the electric field • put a neutron in it: the electric field has no effect

6. The standard model of particles • source: sbhep-nt.physics.sunysb.edu • 6 quarks, 6 leptons and 4 bosons • some have mass, some don’t • mass is expressed in terms of energy  E=mc² • in 2012: Higgs boson! • note: the standard model also acknowledges four forces or fundamental interactions: gravitational, electromagnetic, strong and weak

7. Research and prediction by F. Englert, R. Brout and P. Higgs in 1964 • what causes elementary particles to have mass? • why do some have mass and some don’t? • prediction: there must be a field constructed of an elementary particle that could give mass to elementary particles

8. Mass • not: our mass or the mass of a proton or electron! • proton: 2 up quarks and 1 down quark • together 8 MeV  proton 938 MeV • high amount of energy by constraining the quarks inside the proton • energy is manifested in mass (E=mc²)

9. • particles without mass such as a photon must travel at the speed of light ( c ): – E=γmc² (special relativity) – γ is the Lorentz factor – a photon has energy (E=hf) – this is only possible if v equals c: – this is mathematically undefined but not 0!

10. Theory of the Higgs field • this field exists in all points of the universe • a scalar field in three dimensions • at the bottom: lowest energy • particles without mass circle at the bottom • particles with mass gain their mass as a result of oscillation • source: sbhep-nt.physics.sunysb.edu

11. • particles without mass don’t interact with the field, particles with mass do • conceptual presentation of the field: – a room half filled with water – a person is impeded and slows down when trying to move through the room a particle acquires mass by interacting with the Higgs field – a fish isn’t impeded at all  a particle without mass, e.g. a photon encounters no interaction with the Higgs field

12. The Higgs boson (or BEH boson) • a field is mediated by a boson • the standard forces each have a specific type of messenger particle to exchange information • e.g. electromagnetic interactions  communication by a photon • the Higgs field is mediated by the Higgs boson

13. • the Higgs boson can’t be photographed or detected directly • the Higgs boson was predicted to have a hefty mass of 125-126 GeV • the Higgs boson was predicted to decay immediately into other particles (bottom quarks and W bosons) • these hypotheses have been proved by experiments with LHC in Cern, when 2 protons at very close the speed of light collided and as a result all kind of particles were formed

14. Listen also to http://ed.ted.com/lessons/the-higgs-field-explained-don-lincoln