EldwinSchrodinger @ Graviton?
The graviton is the exchange particle for the gravity force. Although it has not been directly observed, a number of its properties can be implied from the nature of the force. Since gravity is an inverse square force of apparently infinite range, it can be implied that the rest mass of the graviton is zero.
Labels: Elementary Particles
EldwinSchrodinger @ Gluons
Gluons are the exchange particles for the color force between quarks, analogous to the exchange of photons in the electromagnetic force between two charged particles. The gluon can be considered to be the fundamental exchange particle underlying the strong interaction between protons and neutrons in a nucleus. That short-range nucleon-nucleon interaction can be considered to be a residual color force extending outside the boundary of the proton or neutron. That strong interaction was modeled by Yukawa as involving an exchange of pions, and indeed the pion range calculation was helpful in developing our understanding of the strong force.
Gluon interactions are often represented by a Feynman diagram. Note that the gluon generates a color change for the quarks. The gluons are in fact considered to be bi-colored, carrying a unit of color and a unit of anti-color as suggested in the diagram at right. The gluon exchange picture there converts a blue quark to a green one and vice versa. The range of the strong force is limited by the fact that the gluons interact with each other as well as with quarks in the context of quark confinement. These properties contrast them with photons, which are massless and of infinite range. The photon does not carry electric charge with it, while the gluons do carry the "color charge".
Within their range of about a fermi, the gluons can interact with each other, and can produce virtual quark-antiquark pairs. The property of interaction with each other is very different from the other exchange particles, and raises the possibility of gluon collections referred to as "glueballs". The internal state of a hadron is viewed as composed of a fixed net number of quarks, but with a dynamic cloud of gluons and quark-antiquark pairs in equilibrium.
Labels: Elementary Particles
EldwinSchrodinger @ Higgs Boson(s)
The standard model predicts another kind of particles should exist, a "Higgs boson." Experimental proof of its existence will complete the standard model. The precise properties of the higgs boson, and how many higgs boson exist, will give us clues to how the standard model will be extended. For example, supersymmetry (SUSY) predicts that at least five types of Higgs Bosons exist. The existence and properties of higgs Bosons are a special test of the standard model because Higgs Bosons are different from any prevously known kind of particle. Leptons and quarks are basically all particles like electrons, that merely carry different electric, weak or strong charges. Similary, all the quanta that mediate the weak and strong interactions are like the photon. However, the Higgs Bosons that the standard model predicts are really a new kind of matter. If they are found, their prediction and discovery will stand as a spectacular achievement of human reasoning.
Labels: Elementary Particles
EldwinSchrodinger @ Quarks and Leptons
There are 2 more particles like the electron. All their properties are identicle to those of the electron, except that they are heavier, and each is associated with its own neutrino. Although we don't have any idea why is that so, the standard model theory still correctly describes the behavior of these particles. In experiments, various numbers of these particles are produced going in gifferent directions. They are unstable particles, Decaying in less than a millionth of a second into electrons, positrons, neutrinos, and photons, so they do not stay around after they are produced, nor do they end up in anything we see. In all cases, the standard model correctly predicts the number of them, their directions, energies, and lifetimes, and all other aspects of their behavior. One is called the muon, and the other would be the tau. because they behave in similar ways, the electron, the muon, tau, and their associated neutrinos are grouped together in a class of particles called leptons.
Labels: Elementary Particles
EldwinSchrodinger @ Astronomers look to quark stars for a fifth dimension
IF THE universe has weird extra-spatial dimensions in parallel to the 3D world we see around us, then billion-dollar particle accelerators may not be the only place to find them.
So say Gergely Gabor Barnaföldi and colleagues at the Research Institute for Particle and Nuclear Physics in Budapest, Hungary, who propose that extra dimensions may show their face in areas of extreme gravity around dense stars. The concept could also solve a 25-year-old puzzle about the origin of mysterious particles emanating from a distant star system.
Some string theories predict that there are many more dimensions than the four we experience: the 3D world plus time. From next year, particle physicists hope to spot these dimensions at the Large Hadron Collider near Geneva, Switzerland.
Instead, Barnaföldi's team looked to outer space for evidence of extra dimensions interacting with matter. They analysed the Cygnus X-3 binary system, in which a normal star orbits a second object, generally thought to be a neutron star.
Objects in Cygnus X-3 are under extreme gravity, which the researchers say would provide the necessary conditions for extra dimensions to affect matter. Moreover, it spews out ultra-high-energy particles as far as Earth, which the team say could have been tweaked by an extra dimension inside the system. Astronomers believe these high-energy particles, dubbed "cygnets", strike our atmosphere and decay into muons. Since 1981, underground detectors on Earth have recorded sporadic showers of muon particles coming from the direction of Cygnus X-3. The cygnets are a puzzle because no known particles could last the 37,000-light-year journey from Cygnus X-3 to Earth without decaying.
Some astrophysicists have speculated that these long-lived cygnets may originate in a quark star - a hypothetical star that may form when neutron stars collapse. If such quark stars contained a large number of "strange" type quarks, they might radiate out long-lived cygnets. The problem is that so many strange quarks in a star would make it collapse into a black hole.
According to Barnaföldi's team, the necessary stability could be provided by a universe-spanning fifth dimension rolled up into tiny "rings". In most places in the universe, this fifth dimension would not affect matter, but under the extreme gravity conditions inside Cygnus X-3 it could cause other types of quark to behave like strange quarks. "If we could watch these quarks, they would seem to travel along our three dimensions more slowly than expected because, at the same time, they have to circle round this invisible curly extra dimension," says team member Peter Levai. "Effectively they behave as strange quarks."
”If we could watch these quarks, they would seem to travel along our three dimensions more slowly than expected
Fridolin Weber, an astrophysicist at San Diego State University, California, likes the proposal. "Cygnus X-3 is perfect for searching for extra dimensions," he says. "It's basically a cosmic particle accelerator." But he adds that more evidence is needed to explain the cygnets' origin. The work will appear in the journal Astronomische Nachrichten.
Extracted from: New Scientist magazineLabels: Elementary Particles
EldwinSchrodinger @ the fundamentals of particle physics
according to physics, the world is made from 12 fundamental particles called fermions: six quarks and 6 leptons, all the hundred of known particles are actually combination of these! in out everyday life, we will see only what we termed them as err generation I fermions. these are electrons and only up and down quarks combines to form protons and neutrons.
fermions in generation II and III tend to decay into lower generations, and when a heavy lepton (probably a electron, a muon or a tau) decays. and whats the by product is what we actually call them neutrinos
matter particles interact by exchanging force particles, collectively called bosons. at present, the model can explain how force particles carry the strong electromagnetic, and uh week forces. but it cant explain gravity..
by right, all particles have a particular mass, electric charge and spins. and each particle also has a corresponding antimatter particle with the same mass and spins but then it has different electric charge. and when an antiparticle meets a particle, the 2 will annihilate in a flash of energy.
Labels: Elementary Particles
