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| The Elementary Particles, no copyright intended, from scienceblogs.com |
So all of these things are arranged and explained in what we call the Standard Model. But then there are things beyond the the Standard Model, which include the origin of mass, the strong CP problem, neutrino oscillations, matter-antimatter asymmetries, and the nature of dark energy and dark matter. Since I'm not really an expert (hey! I'm only in eighth grade! give me a break), you can look here if you want to look into it: Physics beyond the Standard Model. Many other theories have also been developed as an alternative because some feel that the standard model isn't very good, such as the grand unification theory, the string theory, supersymmetry, technicolor, the preon theory, and the acceleron theory.
Okay, so back to the Standard Model (which if you read the paragraph above, does have so deficiencies and is missing a few things). According to the Standard Model, all of the fundamentals are either bosons or fermions. There are also antiparticles, which are kind of like the dark versions of each particle.
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| The Standard Model, no copyright intended, taken from wikipdedia.org |
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| Elementary Particles chart, no copyright intended, taken from wikipdedia.org |
The Fermions - They Matter
The Fermions are the matter particles. Everything around us is made of matter. These matter particles occur in two basic types, called quarks and leptons. Each group consists of six particles, which are related in pairs, or 'generations'. Six particles divided by pairs of two, make three generations of particles (refer to the chart above if you need to). The lightest and most stable (they don't change as much) particles are in the first generations, while heavier and less stable particles are in the second and third generations. All matter in the universe are made from the first generation particles, while any heavier particles quickly decay into the next most stable level.> Quarks
Quarks combine to make composite particles called hadrons, the most stable of which are protons and neutrons, which make up the nucleus in the atom. There are 6 types, or flavors (chocolate not included), of quarks: up, down, charm, strange, top, and bottom. As I've said before, there are three generations of quarks, the first being the most stable and lightest (up and down), and the second and third heavier and less stable. The heavier particles decay rapidly into the the first generation, therefore to find the second and third generation, we need to use particle accelerators or cosmic rays that use high energy collisions to find them. All quarks also have a spin of 1⁄2 and experience all four fundamental forces.
The Up Quark (u) and the Down Quark (d) - Generation 1
The up quark is the lightest of the quarks, and the down quark is the second lightest quark. Together they are a major constitute of matter, most commonly forming neutrons (one up, two down) and protons (two up, one down of atomic nuclei. Their antiparticles are the up antiquark (u) and the down antiquark (d).
The Charm Quark (c) and the Strange Quark (s) - Generation 2
The charm and strange quarks are the third and fourth lightest quarks, and are also found hadrons. One hadron they're found in is the D
s meson, containing one charm and one strange. Their antiparticles are the charm antiquark (c) and the strange antiquark (s).
s meson, containing one charm and one strange. Their antiparticles are the charm antiquark (c) and the strange antiquark (s).
The Top Quark (t) and the Bottom Quark (b) - Generation 3
The top quark (or the truth quark) and the bottom quark (or the beauty quark) are the heaviest of the quarks. Out of all the particles, the top quark is the heaviest, with a mass of 172.9±1.5 GeV/c2. Because of it's short lifetime, it doesn't form hadrons like other quarks. It mainly interacts with the strong force, but decays through the weak force. The bottom quark gives a distinct signature which makes it fairly easy to identify in experiments (using a technique called B-tagging), and it is also notable in the fact that it is the product of almost all top quark decays. THe bottom quark decays with the weak force, and can also form hadrons. The antiparticles of these quarks are the top antiquark (t) and the bottom antiquark (b).
| > Leptons |
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The leptons are the other main group of matter particles. There are two main groups of leptons: charged leptons and neutral leptons. Charged leptons can combine with various other composite particles like atoms and positronium, while neutral leptons rarely react with anything, therefore are rarely observed.
e).
μ).
Taus (τ−)and Tau Neutrinos (ν
τ) - Generation 3
Taus and tau neutrinos are the third generation leptons. Taus are also quite similar to electrons, and again can also be thought of as larger versions of the electron. Their antiparticles are the Antitau (τ+) and the Tau antineutrino (ν
τ).
The Bosons - May the Forces be with You
There are four fundamental forces in the Universe (which I briefly explained in my 'Spectacular History of the Universe' post), which are: gravity, electromagnetism, and the strong and weak nuclear forces. Gravity is what attracts things based on the amount of mass (how much matter, or 'stuff' if you will, something has in it) something has. Gravity is the weakest of the forces, but it has an infinite range. The electromagnetic force is the force that basically control electricity and magnetism (as if this weren't obvious enough by the name of it). It's range is also infinite, but is many times stronger than gravity. The strong force holds the protons and the neutrons (refer to my 'The Elements (and Atoms too)' post if you're not sure what these are) in the nucleus of atoms together. It and the weak force only have a small range though, dominating the level of subatomic particles. As it's name applies, it's the strongest of the four forces. The weak force is responsible for radioactivity and some other weird stuff that I don't really understand. Like I just said, it only works among the subatomic level. It's much stronger than gravity, but is the weakest of the other three particles.
Electrons (e−) and Electron Neutrinos (ν
e)- Generation 1
The electron, and the electron neutrino are the lightest and most stable of the leptons, and you're also probably most familiar with these. The electron is the lightest of all the particles, having a mass that's about 1/1836 that of a proton's. The electron carries a negative charge while the neutrino carries no charge. Electrons are found in atoms, and the movement they make also make electricity (I hope you know what electricity is. It's what's powering your computer right now and letting you read this post). Their antiparticles are the positron (e+) and the electron anti-neutrino (νe)- Generation 1
e).
Muons (μ−) and Muon Neutrinos (ν
μ) - Generation 2
Muons and muon neutrinos are the second generation leptons. The muon has long meantime for an unstable particle, and it decays into an electron and two neutrinos of different types. Muons are really similar to electrons, the only major difference being that they are 200 times bigger, so can be thought of as a bigger version of the electron. Their antiparticles are the Antimuon (μ+) and the Muon antineutrino (νμ) - Generation 2
μ).
Taus (τ−)and Tau Neutrinos (ν
τ) - Generation 3
Taus and tau neutrinos are the third generation leptons. Taus are also quite similar to electrons, and again can also be thought of as larger versions of the electron. Their antiparticles are the Antitau (τ+) and the Tau antineutrino (ν
τ).
The Bosons - May the Forces be with You
The Photon (v) is the first elementary particle, and it controls electromagnetism. The Gluon (g) controls the strong force. And the W (W±) and Z (Z0) bosons (together known as the weak bosons), control the weak force.
However, we really actually haven't found a boson for gravity yet. In fact, trying to fit gravity comfortably into the framework has proved to be a difficult challenge. The quantum theory used to describe the micro world (the small world, dominated by the strong and weak nuclear forces, and the electromagnetic force), and the general theory of relativity used to describe the macro world (our bigger world, dominated by gravity), are like two children who refuse to play nicely together. But luckily for particle physics, when it comes to the minuscule scale of particles, the effect of gravity is so weak as to be negligible. Only when we have matter in bulk, such as in ourselves or in planets, does the effect of gravity dominate. So the Standard Model still works well despite its reluctant exclusion of one of the fundamental forces.
But the Picture isn't complete yet...
The hunt is on for the for the Higgs Boson!
But wait... that's not all! There's... more! Scientists aren't sure why some particles are really really heavy, while others are really really light, even though they're exactly the same size. So this guy named Peter Higgs developed the theory of the Higgs field, in which particles that are more massive would interact with the field more, while less massive particles would interact less, or not at all with the field. The Higgs Boson is just one piece of the Higgs field. Now this can be pretty confusing, so if you want to hear an expert (unlike me xD), then watch this video!
We haven't found this yet in any experiment made, but we're pretty sure it's out there somewhere... who knows? Maybe you'll be the one who finds it someday!
What is a Higgs Boson?, Fermilab Scientist Don Lincoln
CERN: The Standard Model of Particle Physics
