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Some details on how information is extracted experimentally for the future:
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Forces: There is a centrifugal force on the quarks as the they orbit with some momentum. This force should manifest naturally due to the fact that the quarks have some intrinsic energy which means they must be given an initial momentum. There is the color charge force (strong force) which is the flux tube that brings binds the quarks together. There is electricity and magnetism that are applied to all of the charged quarks. The string tension should go as 1/r where r is the distance. The force between valance quarks should go as F(r)=Ar+BrCr. In other words, at small r where the quarks are close together, there is a spring constant A. As r gets bigger (beyond the diameter of the proton) then the attractive force gets stronger and stronger very fast (try A=0.3, B=0.1 C=2.9). The sea quarks should go as F(r)=a/r2+b where r is again the distance between them. Both a and b are constants that play a role in the spatial region that each term kicks in. The sea quarks actually undergo a gluon-mediated scattering interaction governed by an inverse square law just like Coulomb’s law. The difference is that there’s a second term in the equation, and it’s a constant. Regardless of the distance between them, two “unpaired” quarks will be attracted to each other with a constant force on top of the inverse square law which is 137 times stronger than the electromagnetic force. So a is 137 times the scale of the force between two charges (Coulomb's Law) and b should be on the same scale as a. Here I've provided some starting parameters but we should have these parameters be something that we can change in our menu by at least 10%.
FluxTubes: Quarks are connected via the flux tubetubes. The flux tube can be modeled as just a string holding the valence quarks together. The three valence quarks should be orbiting around the center of the proton with a momentum that wants to send them flying off but the string tension of the flux tube keeps them bound to each other. The string tension and the valence quark momentum should be control parameters that can be changed in the UI. When the proton is polarized the orbital motion is correlated to the proton's spin when the proton is not polarized the spin direction is chaotic. The up quark and the down quark rotate in opposite directions. The up quark has a mass of about 2 MeV while the down quark has a mass of about 4.8 MeV so the up quark is about 2.4 times faster than the down quark. The momentum of the quarks is faster when the quarks are closer together in the center of the proton and slow when they are farther apart. The flux tube should get smaller (narrower) as its stretches and the tension tighten. The flux tube is a three-dimensional geometry that has an empty volume inside. Gluons can pass through the volume changing the color of the quarks as they make an exchange. This happens exactly the same in both valence and sea quarks. The valence will always have three flux tube arms while the sea can have two or three or more but normally only two.
Gluons: Each Gluon has two colors as indicated on the Wikipedia page under Color Charge. All combinations of gluon colors should be represented. There are three colors and three anti-colors red, gluon, blue, and anti-red, anti-green, and anti-blue. You can use the same color representation as what you see on Wikipedia. Each gluon can float around and interact with other gluons and quarks. Gluons can do nothing, attract one another and annihilate turning into two photons. They can only annihilate if the total color charge of the two gluons is color-neutral. Only gluons that can form white will interact. For example, a red and anti-red can interact with another red and anti-red gluon. Three gluons all of different colors can form two color-neutral states. They In this way, gluons can also interact with each other to make pure gluon states. Other than that all they do is swarm around and interact with the quarks. When they make contact, they can bounce off each other changing from attracting to repelling, or they can pass right through each other. When the gluon density is large more sea quarks pop in and out of the vacuum. Space is full of fluctuating waves/swarms of gluons increasing and decreasing the likelihood of QCD making something happen. The gluons continuously pop in and out of existence but the swarm is always present. As the flux tubes move in space they clear out the fluctuating gluons in the vacuum. The probability of gluon sea-quark interaction is inversely proportional to the sea-quark virtuality.
Quarks: The quarks are charged so besides the color force there is an electromagnetic force as well. This is true for the sea quarks and valence quarks. The Up quark has a charge of +2/3, and the Down quark is -1/3. This is important in the physics of their dynamics because when charges move, they make magnetic fields. The force from the electromagnetic charge scales as 1/r^2, where r is the distance between the quarks (charges). The color force on the other hand does not diminish as fast over distance, it is the same between quarks but will normally only act between two (sea-quarks) or three (valence quarks). The strength of the color force is roughly 137 times that of the electromagnetic force. When the proton is polarized the orbital motion is correlated to the proton's spin when the proton is not polarized the spin direction is chaotic. The up quark and the down quark rotate in opposite directions. The up quark has a mass of about 2 MeV while the down quark has a mass of about 4.8 MeV so the up quark is about 2.4 times faster than the down quark. The momentum of the quarks is faster when the quarks are closer together in the center of the proton and slow when they are farther apart. The valence quarks orbit the center of the proton with Up and Down going in different directions but also following chaotic and wild paths when unpolarized. Polarized protons have much more order with the valence quarks always orbiting the central axis. The sea quarks can also orbit the central axis and follow and interact with the valence quarks. There are sum-rules that govern the exchange between orbital angular momentum, and partonic spin, and how all of this is shared between all the pieces.
Models of Dynamics:
Spin Sum Rule: All of the components of parton spin and dynamics must lead to a total proton spin of 1/2. Its not possible to make this work without imposing some model dependence so its very important that all the above aspects are addressed first. Since the famous EMC experiments revealed that only a small fraction of the nucleon spin is due to quark spins, there has been a great interest in ‘solving the spin puzzle’, i.e. in decomposing the nucleon spin into contributions from quark/gluon spin and orbital degrees of freedom. In this effort, the Ji decomposition:
not only the quark spin contributions ?q but also the quark total angular momenta. Charged particles in a magnetic field are governed by a velocity EXB an orbital angular momentum L=rXEXB where r is the position vector [ref]. This means that the charges will orbit the center of the proton in opposite directions. This however is a very classical picture. The terms in the above equation are defined as quantum mechanical expectation values of the corresponding terms in the angular momentum tensor. A representation of this decomposition should start with the valence quarks and include the intrinsic spin of the quarks that hold the know spin percentage (randomly oriented otherwise). Then the OAM is represented classically as rotating charges in a B-field.
Meson Cloud Model: At any given instant, the proton might really be a neutron (ddu) plus a positively charged pion (ud- ud-)—or another proton (uud) plus a neutral pion. This violates energy conservation but it is allowed, for a fleeting moment, by the Heisenberg uncertainty principle. By adding up the contributions from all the possible channels, the theorists can model the composition of the sea.
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Sivers Effect: Map the distribution of unpolarized quarks in 3-dimensional momentum space. A simple first test sea quark model might be to make a single 0++ state with both sea-quark spins pointing down and the OAM pointing up. These should orbit the central axis just like the valence in the pattern extracted from the data. We should make the sum rule worked by forcing spin, OAM and momentum be conserved.
UI and Controls:
We also want a nice User Interface that is transparent so you can still see what's going on behind it and provides the option of controlling all of the dynamics and
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Member | Year | Unity | Major | Project | Team | Notes |
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Duncan Beauch | 3rd year | Novice | Physics/CS | Views and UI and Expanding 3D representation (+ physics team work) | Physics | |
Wyndham White | 3rd year | Novice | Physics/CS | Unity Fluid simulation tests (+ physics team work) | Physics | |
Bryant Lisk | 2nd year | Novice | CS | gluon-quark/gluon-gluon/fluxtube force | Modeling | |
Jared Conway | 2nd year | 2 years | CS | Electricity and Magnetism of quarks (Unity EM engine) | Modeling | |
Sam Colvin | 2nd year | Novice | CS | Optimization for high particle density | Modeling | |
Ethan Hanover | 4th year | 3 years | CS | Sea-quark, gluon, fluxtube interactions | Dynamics/Modeling | |
Ishan Mathur | MS student | CS | CS Integration and communication | Systems Organization | ||
Ishara Fernando | Postdoc | Physics | Physics Integration and communication | Systems Organization | ||
Liliet Diaz | Phd student | Physics | Physics team lead | Physics |
Misc. documents
- GitHub_Steps.pdf
- https://www.uni-muenster.de/Physik.TP/archive/fileadmin/lehre/Quantenmechanik_Friedrich_/book1_01.pdf
- https://arxiv.org/abs/1907.11903