Thursday, July 26, 2012
PM statement on discovery of new sub-atomic particle - Number 10
PM statement on discovery of new sub-atomic particle - Number 10 recommended by http://www.nationalstemcentre.org.uk/blog/the-higgs-is-here-probably
The Best Resources For Learning About Higgs Boson, The “God Particle” | Larry Ferlazzo’s Websites of the Day…
Thursday, July 12, 2012
Wednesday, July 11, 2012
The Standard Model - The Physics Hypertextbook
The Standard Model - The Physics Hypertextbook
Subdivides the Standard Model families and particles really well.
Subdivides the Standard Model families and particles really well.
Video: Brian Cox's guide to quantum mechanics | The Hunt for the Higgs
Video: Brian Cox's guide to quantum mechanics | Science | guardian.co.uk
"Imagine a world where particles can pop into existence seemingly out of nothing and disappear just as quickly. Imagine a world where you can be everywhere in the universe at the same time and yet nobody can know precisely where you are. According to our best theory of nature the Standard Model of Particle Physics, this is exactly how the world behaves because at its heart lies the strange theory of quantum mechanics."
"1905 Photoelectric Effect: ... Einstein said light is a stream of particles (photons) not a wave. The energy of each wave depends only on the colour, not on the intensity of the light.
Instead of thinking of forces in terms of forcefields as Newton and Maxwell had done, in 1940 Quantum Electrodynamics QED was invented by Feynmann. QED explains all of physics outside the nucleus except gravity and explains interactions of matter particles with one another via the electromagnetic force which drives all of chemistry. A theory of (almost) everything! When electrons get close to each other they move away because like particles repel one another. QED explained electromagnetic force in terms of particles. This repelling action is caused by a quantum of light, a photon being exchanged between the electrons.
By 1970s QED explained the strong nuclear forces which requires 8 Gluon particles and the 3 weak nuclear force particles - the W+, W- and Z. With E=mc2 means that if you smash particles together you get energy. The gluon was found in the 1970s, the W and Z particles in the 1980s. From Einstein's equation, a lot of energy is required to make a lot of mass, the W and Z particles were like the gluon and photon but with more mass than an atom of copper.
"Imagine a world where particles can pop into existence seemingly out of nothing and disappear just as quickly. Imagine a world where you can be everywhere in the universe at the same time and yet nobody can know precisely where you are. According to our best theory of nature the Standard Model of Particle Physics, this is exactly how the world behaves because at its heart lies the strange theory of quantum mechanics."
"1905 Photoelectric Effect: ... Einstein said light is a stream of particles (photons) not a wave. The energy of each wave depends only on the colour, not on the intensity of the light.
Instead of thinking of forces in terms of forcefields as Newton and Maxwell had done, in 1940 Quantum Electrodynamics QED was invented by Feynmann. QED explains all of physics outside the nucleus except gravity and explains interactions of matter particles with one another via the electromagnetic force which drives all of chemistry. A theory of (almost) everything! When electrons get close to each other they move away because like particles repel one another. QED explained electromagnetic force in terms of particles. This repelling action is caused by a quantum of light, a photon being exchanged between the electrons.
By 1970s QED explained the strong nuclear forces which requires 8 Gluon particles and the 3 weak nuclear force particles - the W+, W- and Z. With E=mc2 means that if you smash particles together you get energy. The gluon was found in the 1970s, the W and Z particles in the 1980s. From Einstein's equation, a lot of energy is required to make a lot of mass, the W and Z particles were like the gluon and photon but with more mass than an atom of copper.
ATLAS Experiment -
ATLAS Experiment
"The Higgs Boson is an unstable particle, living for only the tiniest fraction of a second before decaying into other particles, so experiments can observe it only by measuring the products of its decay. In the Standard Model, a highly successful physics theory that provides a very accurate description of matter, the Higgs Boson is expected to decay to several distinct combinations of particles, or channels, with the distribution among the channels depending on its mass."
"ATLAS concentrated its efforts on two complementary channels: Higgs decays to either two photons or to four leptons. Both of these channels have excellent mass resolution; however, the two-photon channel has a modest signal over a large but measured background, and the four-lepton channel has a smaller signal but a very low background. Both channels show a statistically significant excess at about the same place: a mass of around 126 GeV. A statistical combination of these channels and others puts the significance of the signal at 5 sigma, meaning that only one experiment in three million would see an apparent signal this strong in a universe without a Higgs."
"The current results are an update on previous analyses shown at a CERN seminar last December and published at the beginning of this year. The December results, based on 7 TeV proton collision data collected in 2011, limited the mass of the Higgs Boson to two narrow windows in the range between about 117 GeV and 129 GeV. A small excess of events above the expected background was seen by both ATLAS and CMS at around 126 GeV, about the mass of an iodine atom."
"The Higgs Boson is an unstable particle, living for only the tiniest fraction of a second before decaying into other particles, so experiments can observe it only by measuring the products of its decay. In the Standard Model, a highly successful physics theory that provides a very accurate description of matter, the Higgs Boson is expected to decay to several distinct combinations of particles, or channels, with the distribution among the channels depending on its mass."
"ATLAS concentrated its efforts on two complementary channels: Higgs decays to either two photons or to four leptons. Both of these channels have excellent mass resolution; however, the two-photon channel has a modest signal over a large but measured background, and the four-lepton channel has a smaller signal but a very low background. Both channels show a statistically significant excess at about the same place: a mass of around 126 GeV. A statistical combination of these channels and others puts the significance of the signal at 5 sigma, meaning that only one experiment in three million would see an apparent signal this strong in a universe without a Higgs."
"The current results are an update on previous analyses shown at a CERN seminar last December and published at the beginning of this year. The December results, based on 7 TeV proton collision data collected in 2011, limited the mass of the Higgs Boson to two narrow windows in the range between about 117 GeV and 129 GeV. A small excess of events above the expected background was seen by both ATLAS and CMS at around 126 GeV, about the mass of an iodine atom."
http://atlas.ch/news/images/stories/4-plot.jpg
The probability of background to produce a signal-like excess, for all the Higgs boson masses tested. At almost all masses, the probability (solid curve) is at least a few percent; however, at 126.5 GeV it dips to 3x10-7, or one chance in three million, the '5-sigma' gold-standard normally used for the discovery of a new particle. A Standard Model Higgs boson with that mass would produce a dip to 4.6 sigma.
Tuesday, July 10, 2012
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