The Higgs boson and Higgs field

slidecast for CLIL

Veerle De Cock

February 2014

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

• 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

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

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

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

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

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)

• 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!

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

• 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

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

• 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

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