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What Is a Quirk? Essay Sample

What Is a Quirk? Pages
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First of all, there are actually 6 kinds or flavours as they are usually called, of quarks: up, down, top, bottom, strange and charm quarks. They are part of the elementary or base particles in the Standard Model, a table of sixteen elements which incorporate the mass, spin, electromagnetic force and name. The only force that quarks have that is not represented by the Standard Model would be color charge which will be explained later. Quarks are classified in the top left corner of the table and they belong to a family of particles called fermions. They are actually classified in three generations or pairs, which are the first generation up and down quarks, the second generation strange and charm quarks and the third generation top and bottom quark. Following the discovery of these there have been attempts at finding a fourth generation but at this time all attempts have failed. One of the qualities that puts the quark in the fermions’ is it’s spin, because all quarks are spin-1/2 particles, which classifies it as a fermion according to the spin statistics theorem.

Quarks are the only particles that have all of the fundamental interactions or forces which include the afore said electromagnetism plus gravitation, strong interaction and weak interaction. Above all however, the main characteristic of quarks is that they are the only particles which do not have integer, that is to say whole number multiples, electric charges. Any of the quarks is also able change into the other quarks in its generation by a process called particle degeneration which is where the mass of one of the quark changes thus transforming it into its partnering quark. Of course everything must have an opposite and the same is true with quarks because there are also anti-quarks which are almost identical to regular quarks but have the opposite electric charge.

The combinations that quarks and anti-quarks produce are either called hadrons, mesons or baryons depending on their proportions. Protons and neutrons, the most stable hadrons, are formed of 2 up quarks and 1 down quark or 1 up quark and 2 down quarks respectively. Baryons are made up of 3 quarks, thus the anti-baryon is made up of 3 anti-quarks, and mesons are made of one regular quark and one anti-quark, usually the same flavor as the regular one. There have also been experiments to determine if there might be other «exotic» hadrons which would have up to four of five valence quarks but to this day there has been no proof of their existence. History of the quark:

In the beginning no one knew that quarks actually existed. They simply came into existence, as a term, for explaining something they did not know of. At that time the particle zoo, that is to say the know particles at the time, consisted mostly of what we now call hadrons so they would have been particles similar to the proton and neutron. Then there came along a certain Murray Gell-Mann and his partner George Zweig who proposed that the particles that they did know of were not the smallest that there were but rather that each of these were made up of smaller ones. The term they used to explain these smaller particles were, indeed, up, down and strange quarks, although they did not have any evidence of their existence. The correct term for what they used quarks for would be an «abstract representation». The year after this proposal Sheldon Lee Glashow and James Bjorken suggested a forth flavor of quarks called charm to better explain the weak interaction between the particle, causing particle decay.

The discovery of this new quark made it so that the number of quarks they knew of equalled the number of leptons they knew existed plus it lead to a formula for calculating mass which correctly reproduced the same masses as those of the known mesons. Then in 1961, Murray Gell-Mann and George Zweig came back with a particle classification system for quarks called the Eightfold Way which demonstrated flavor symmetry and then again in 1964 to show off their new quark model. But up to this point there was no actual evidence that quarks existed. It was only four years later in a deep inelastic scattering experiment at SLAC that the discovery was made that the proton was indeed made up of miniscule point like objects thus making the proton disappear from the list of elementary particles.at the time of the discovery, and still used from time to time today, these were called partons. Later they realised that they were actually the fabled up and down quarks. The rest of the quarks were discovered one at a time until the last quark, the top quark, was discovered in 1995. The team that discovered this particle were immensely surprised at its mass because it was so large. It is said to have a mass «almost as great as a gold atom». Standard model:

The standard model is composed of (in order from left to right in rows of 4): up quark(u), charm quark(c), top quark(t), photon(y), down quark(d), strange quark(s), bottom quark(b), gluon(g), electron neutrino(Ve), muon neutrino(Vµ), tau neutrino(VƮ), Z boson(Z°), electron(e), muon (µ), tau(Ʈ), W boson(W±). Plus the Higgs boson (H°) which was recently discovered but is not included in the model. There are also the anti-particles which, though they are not on this table are the same elements, are indicated as the symbol with a bar over top of it.

Quark properties:
Electric charge: This comes in positive and negative and it is present in every kind of matter because this is one of the components that hold matter together. Positively charged particles are attracted to negatively charged particles, and vice-versa, but they are repelled by other positively charged particles. The electric charge of a substance is usually referred to or measured in coulombs but when working with particles and atoms, the usual electric measurement is in elementary charge designated by the symbol e. One e is equal to 1.602x 10 to the -19th power. One proton has an electric charge of e and an electron has an electric charge of –e, however, if we delve into quarks the measure of electric charge is measured in 1/3e.

The up, charm and top flavor of quarks have charge of +2/3e while down, strange and bottom flavor quarks have a charge of -1/3e. Their corresponding anti-quarks have the same amount of electric charge but the opposite charge. In hadrons, the total charge will always equal integer charges, such as in protons and neutrons have +1 and 0 respectively, and are usually made up of 3 quarks (baryons), 3 anti-quarks (antibaryon) or a quark and an anti-quark which always have an integer charge (mesons)

Spin: Spin is an intrinsic component of elementary particles, meaning that it is independent of the amount of matter there is or any other obstacles. So spin is completely free of any obstructions but it is its direction that gives the particle an important degree of freedom, which determines the substances state. However, the spin of a particle is not like the earth spinning around the sun but rather like the earth’s wobble on its own axis, 23.5°, were the earth not moving and spinning at high speeds, sometimes nearing the speed of light. Spin is therefore a vector constant, which has speed and direction, and it determines the amount of electromagnetism the particle will have depending on how quickly it is spinning. Quarks have the lowest degree of spin (for it is not measured in distance per time but rather degree per time) which is equivalent to + or- ħ/2 where ħ is the reduced Planck constant, the smallest quantity possible. This is why quarks, protons, neutrons and other fermions are referred to as spin-1/2 particle.

These types of particles must also obey the Pauli Exclusion Principle which dictates that no two fermions, mainly electrons, can occupy the same state or space as another at the same time. Weak interaction: It is true that quarks can go from an up-type quark (up charm or top) to any down-type quark (down, strange or bottom) but this can only occur because of one of the four fundamental interactions, weak interaction. Weak interaction is where a particle, like the quarks, absorb a W-boson to go from down to up or releasing a W-boson to go from up to down. This is in turn possible because the quarks are named after their mass and the way they react so by adding a W-boson, the mass goes up and the particle adheres to the particle causing it to behave slightly differently.

The emission or reception of a W-boson is a process that is called beta decay which is a radioactive process which usually “splits“ a neutron into a proton and an electron and an electron neutrino. This happens because one of the down-type quarks in the neutron emits a virtual Wˉ boson, which means a particle that only exists for a limited amount of time and space, which then turns the down quark into an up type turning the neutron (udd) into a proton (udu). The Wˉ boson then veers off and becomes an electron (eˉ) by absorbing an electron antineutrino (V̄e). Now, while any of the up-type quarks can turn into any down-type quarks, they do prefer to change into their corresponding quark, which is the other quark in their generation. There is also another weak interaction graph/matrix made for the leptons (right side of table) which together can explain all of the connection between the quark flavors but the links between the two graphs are not clear yet.

Strong interaction and color charge: Quarks are said to each have a color charge and there are three types of color charges labelled red, green and blue. The corresponding anti-quarks have colors of their own which are the anti-colors or antigreen, antired and antiblue (antigreen=magenta, antired=baby blue, antiblue=yellow). These particles are able to act in this manner because of a mediator particle called gluons which are force carrying particles carrying the color force. Thus when a quark and an anti-quark combine, the resulting color charge has a value of 0. The color force or strong interaction is explained better with the special unitary groups but these are too complicated for my understanding.

Mass: When calculating the mass of quarks there are two different masses to take account of. There is the “current quark mass“ which is the mass of the quark by itself and then there is constituent quark mass which is the combined mass of the quark and the gluon field that surrounds it. It is interesting to know that, even though gluons are practically massless, they are the main body of the quarks mass. This is because of the amount of energy they carry. So while the mass of the three quarks of a proton is only 11MeV/c², the mass of the hadron is approximately 938MeV/c². The name for the kind of energy the gluons possess is called quantum chromo dynamics binding energy or QCBE. The Standard Model derives the masses of these particles with help from the Higgs mechanism which is in relation to the Higgs boson. Other properties:

Total angular momentum: Total angular momentum is a parameter that includes both the orbital angular momentum of a particle combined with its intrinsic angular momentum, otherwise known as its spin number. The total angular momentum is measured by a quantum number (j) and this number is used very often in the field of physics. Baryon number: The baryon number of a particle is the remaining spin quantum number left when the quarks and anti-quarks in the baryon are counted. For example, a meson will have a baryon number of 0, a baryon will have +1 and an antibaryon will have -1. Other more exotic hadrons could also be considered to be baryons depending on their baryon number. Isospin: Oddly enough, the isospin is a number that does not have either spin or angular momentum. Isospin is actually named so because of the resemblance of its mathematical formula to that of the formula for the spin of particles.

Is a number that enables the person to understand the different possibilities of spin for that kind of particle. For example, the isospin number for a proton or a neutron would be I3=+1/2 or -1/2 because protons and neutrons are almost exactly alike in every aspect except their charge. Charm: The charm number is simply a number that represents de differential between the number of charm quark and number of anti-charm quarks. Strangeness: Strangeness is a number that indicates the difference between the number of strange quarks versus the number of anti-strange quarks. Topness: Topness is a number that indicates the difference between the number of top quarks and anti-top quarks.

Bottomness: Bottomness is a number that indicates the difference between the number of bottom quarks and anti-bottom quarks. *
Note that for the charm, topness, bottomness, and strangeness numbers are rarely used because the regular strange, bottom, charm or top quarks have a +1 value and their corresponding anti-quarks have a -1 value.

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