The Theoretical: What is pion (virtual) exchange? What are pions?

 

The Theoretical: What is pion (virtual) exchange? What are pions?

By: Ian Davis
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Credit and found: https://www.google.com/url?sa=i&url=https%3A%2F%2Fphysics.stackexchange.com%2Fquestions%2F616015%2Fquick-question-about-gluons&psig=AOvVaw31YpwcrVZaPCihzcLmd2Lj&ust=1638990689898000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCLCC4KKy0vQCFQAAAAAdAAAAABAJ

Introduction:

While researching my exotic mesons and multi-quarks blog, I was introduced to this topic, and I have stumbled across it. My earlier definition stated that it was just a strong force interaction; however, I will go further in-depth because I don't believe that is the limit to this. I have no true idea of what I am about to get into, but I do know a bit of pion, and from my previous research, I can already infer what is going on. But for now, let's get into it.

My Research:

A pion is a meson but with an anti-quark and quark pair. However, Google states that the definition of a pion is a meson that is 270 times the mass of an electron, pretty broad. For this sake, since they are rudimentary definitions, I will state that they are one large definition. They also happen to be not restricted by the Pauli Exclusion Principle, meaning that no two fermions can occupy the same quantum state with a half-integer. They are typically produced in various interactions since their shape and idea are straightforward. However, they do not appear in a normal matter system because of the energy needed to create them (general increase of the system's total energy as a whole, so more energy would have to be added on), meaning they are typically synthesized or are byproducts. They appear when their interactions with nucleons like neutron and protons create a mass that is lower for the nucleon but is comparable to the pion, which typically happens when regular matter or baryonic matter reaches critical density or around 10^15 g/cm^3. This is very theoretical because of the recent and modernism of these properties. 

" An animation of the nuclear force (or residual strong force) interaction. The small colored double disks are gluons. For the choice of anticolors, see Color charge § Red, green, and blue." - Credit and found: https://en.wikipedia.org/wiki/Pion

Pions are not typically born from radioactive decay, but instead, they are usually produced by high-energy collisions with hadron to hadron collisions. They also come from matter and antimatter annihilation due to the high energy and the mass vindicated. Not just that, but natural processes can produce them, like when gamma rays from supernovas indicated they were found in that wreckage, as well as cosmic rays down here on Earth. 

Credit and found: https://www.google.com/url?sa=i&url=https%3A%2F%2Fsciencenotes.org%2Fwhat-is-antimatter-definition-and-examples%2F&psig=AOvVaw13u0QX519FI4qbZnm907yI&ust=1639244495611000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCKjW6ePj2fQCFQAAAAAdAAAAABAD

There are three different types of pions, π0, π+, and π−, or neutral, positive, and negative, respectively. All are unstable since the pion in and of itself is unstable, with an average lifetime of 26.033 nanoseconds (2.6033×10−8 seconds), except for the neutral pion, which decays even faster at 85 attoseconds (8.5×10^−17 seconds) and decays into gamma rays. The charged pions, like π+ and π− will decay into byproducts, like muons and muon neutrinos, or more simply a variation of an electron that is a lepton. 

Credit and found: https://www.google.com/url?sa=i&url=http%3A%2F%2Fhyperphysics.phy-astr.gsu.edu%2Fhbase%2FParticles%2Fhadron.html&psig=AOvVaw1AR8pFjmU3FnbwypGh6PDA&ust=1639244240721000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCOC8oOji2fQCFQAAAAAdAAAAABAJ

Pions are mesons with no or zero spin and are a part of the first generation of quarks. The compositions and all properties are in the spreadsheet pdf I made here:

PionCompositionGenerationDecay ByproductSpinLifetimeEquationMassInteractionsAntiparticleOther
π+ Discovered = 1947up quark, anti down quark
1stPositive muon, muon neutrino, positron, neutral pionRegular spin=0 Isospin=+126.033 nanoseconds (2.6033×10−8 seconds)
π+→ μ+ + νμ
π+→e+ + νe
~139.6 MeV/c2All forcesπ-Hypercharge = 0
Parity = -1
C parity = +1 Color Charge = 0 Electric Charge = +1
π− Discovered = 1947down quark, anti up quark1stNegative muon, anti moun neutrino, neutral pion, electronRegular spin=0 Isospin=-126.033 nanoseconds (2.6033×10−8 seconds)π−→ μ− + νμ π−→ e− + νe
~139.6 MeV/c2All forcesπ+Hypercharge = 0
Parity = -1
C parity = +1 Color Charge = 0 Electric Charge = -1
π0 Discovered = 1950up quark and anti up quark or down quark and anti down quark1stGamma-ray (98.8% of the time), electron, positronRegular spin=0 Isospin=085 attoseconds (8.5×10^−17 seconds)π0→2γ

π0→γ + e− + e+

π0→e− + e+ + e− + e+

π0→e− + e+
~135.0 MeV/c2All forcesItselfHypercharge = 0 Parity = -1 C parity = +1 Color Charge = 0 Electric Charge = 0

Pions are thought to be the maximum range of the limited range of the strong interaction, as it's used as an exchange, a "pion" exchange. The strong interaction reacts with all pions the same, just as long as it's a pion. It fits within the uncertainty principle, that is, that you cannot measure a position and a velocity of an object with 100% accuracy at the same time, one with 100% is accurate, but never both at the same interval. This creates a "virtual" particle or a particle that s fitting within the uncertainty principle. It cannot travel to another particle (N-N interaction, or Nucleon to Nucleon interaction) faster than the speed of the universe (it has mass, so, therefore, cannot travel faster than light, which is uncommon because exchange article typically doesn't have this property and go the speed of light, making it nearly an infinite range), also known as c times that lifetime, and like before, within the range of the strong interaction is about its range. Pion's can technically escape this conformality by escaping the uncertainty principle, but that is hard to do. 

Credit and found: https://www.google.com/url?sa=i&url=http%3A%2F%2Fwww.sliderbase.com%2Fspitem-1108-4.html&psig=AOvVaw3lXwjRGyvB3VZH0gpjLWtX&ust=1639244587450000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCNDa_o3k2fQCFQAAAAAdAAAAABAW

Pions may also exchange between unconventional objects, like exotic mesons and weird particles that most likely don't live long. Still, they do give insight into how strong interaction works. These particles consist of vector mesons, rho mesons, and omega mesons. The various types of vector mesons are mesons with a total spin of 1, odd parity, and are usually byproducts from other reactions. Rho mesons are of the same blood, as they a short-lived hadronic particle (real mass), and has an isospin triplet, or three states called ρ+, ρ0, and ρ−  and a mass of 770 - 775.45±0.04 MeV. Omega mesons are flavorless mesons with an up quark-antiquark and a down quark-antiquark pair. All three of those mesons are technically vector mesons and part of their nonet. They also sometimes accompany the pion to mediate the strong force, but not near as much as the pion itself. Known mesons that are vector mesons are as follows: ρ meson, ω meson, φ meson, K*(892) meson, D* meson, J/ψ meson, and ϒ meson. 

Credit and found: https://www.google.com/url?sa=i&url=http%3A%2F%2Fhyperphysics.phy-astr.gsu.edu%2Fhbase%2FParticles%2Fhaddia.html&psig=AOvVaw2QfZjE97uSASxyvoHge42D&ust=1639244639872000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCNihqbTk2fQCFQAAAAAdAAAAABAD

Let's explore the virtuality of these pions a little more. We know that being virtual relates to an exchange particle undergoing scrutiny from the uncertainty principle while traveling to another nucleon (Nucleon - Nucleon Interactions). By definition, virtual particles undergo quantum fluctuation, also known as experiencing a random change in energy levels whilst traveling throughout space, very tiny fluctuations, and only elementary particles gain it. These particles' mass and energy will typically have "~" or "+/-" per these fluctuations. A rule of thumb is that the more a virtual particle gets closer to an ordinary particle characteristic, the longer it will exist, and in reverse as well. Feynman diagrams are exemplary at showcasing the interactions of these, as well as they serve in the same case for other virtual particles:
Credit and found: https://www.google.com/url?sa=i&url=http%3A%2F%2Fhyperphysics.phy-astr.gsu.edu%2Fhbase%2FParticles%2Fexpar.html&psig=AOvVaw2zjF8gLQYy60q7N1q8LQX-&ust=1638990613850000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCODqp_6x0vQCFQAAAAAdAAAAABAD

Pions may also violate the law of conservation of mass and energy. When a proton releases a positive pion, it can change the identity of the receiving nucleon, like a neutron, to switch to a neutron. Since this is done with a positive pion, it takes the positive energy away from the proton, forming a neutron, and then adds it to the neutron, forming a proton. Since the Heisenberg Uncertainty Principle is in effect, the pion cannot live for long, or like the average lifetime of the positive pion. Due to the finite range of the strong force, you can denominate the mass and lifetime of the object traveling as it loses mass while traveling. The shorter the receiver, the stronger and more mass the exchange particle will contain. 


"The strong nuclear force is transmitted between a proton and neutron by the creation and exchange of a pion. The pion is created through a temporary violation of conservation of mass-energy and travels from the proton to the neutron and is recaptured. It is not directly observable and is called a virtual particle. Note that the proton and neutron change identity in the process. The range of the force is limited because the pion can only exist for a short time, as allowed by the Heisenberg uncertainty principle. Yukawa used the finite range of the strong nuclear force to estimate the mass of the pion; the shorter the range, the larger the mass of the carrier particle." - Credit and found: https://courses.lumenlearning.com/physics/chapter/33-1-the-yukawa-particle-and-the-heisenberg-uncertainty-principle-revisited/.

The person who proposed all of this and basically built most of this pion/meson information and model is the great Hideki Yukawa, who lived from 1907-1981. He has gained a lot of notoriety and was the first Japanese Nobel laureate. He has written many books like Introduction to Quantum Mechanics (1946) and Introduction to the Theory of Elementary Particles (1948) while also editing journals and articles for Americans and other physicists. He is known as one of the greatest physicists, at least in my book.

Credit and found: https://www.google.com/url?sa=i&url=https%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FFile%3AHideki_Yukawa_1949c.jpg&psig=AOvVaw3fmBIBlKW1YLixozr8_VtA&ust=1639244778945000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCJCK6unk2fQCFQAAAAAdAAAAABAD

Final Conclusion:

Overall, the pion exchange is harder to pronounce than define, and we will go over it simply quickly. Pions are a type of particle with two quarks in them, usually an up or down quark, and there are also three types of pions, the positive one, the negative one, and the rare neutral one. Pions are often used as exchange particles, that is, a particle used to exchange forces between other subatomic particles, in this case, the strong force and the nucleons. 

Virtual particles are exchange particles that are affected and basically created by quantum fluctuations, but they are transient, they exist for a very short time, this is all limited by the uncertainty principle. 

Since it is not directly observable, they call them virtual particles or virtual pions in this case. These pions are a temporary violation of one of the basic rules of the universe, the conservation of mass and energy, as they have higher energy than released (most likely from quantum fluctuations as well) and is shot usually from one nucleon (proton) to another (neutron) and is recaptured, almost like a rocket leaving earth with a lot of energy, then using it to get to the moon. When transferring from one nucleon to the other, it may change the identity of both, like x=proton and y=neutron, and then after the exchange, x=neutron, and y=neutron (positive pions can do this)

The man, the myth, and the legend who developed this side of the field and most of the information I have just talked about is Hideki Yukawa, a Japanese physicist and the first Japanese Nobel Prize winner for physics.

What do you think about pions? What would you like to know about exchange particles and being "virtual?" Let me know in the comments below. 

Credit and found: https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.britannica.com%2Fscience%2Fpi-meson&psig=AOvVaw0pI-YWmC6treFXKgmF_pO5&ust=1639244898485000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCNjmvKPl2fQCFQAAAAAdAAAAABAK

Sources: 

https://en.wikipedia.org/wiki/Vector_meson

https://en.wikipedia.org/wiki/Omega_meson

https://en.wikipedia.org/wiki/Rho_meson

https://en.wikipedia.org/wiki/Virtual_particle

https://www.nobelprize.org/prizes/physics/1949/yukawa/biographical/

https://courses.lumenlearning.com/physics/chapter/33-1-the-yukawa-particle-and-the-heisenberg-uncertainty-principle-revisited/

https://www.youtube.com/watch?v=ZQQY89lcWUI

https://www.youtube.com/watch?v=wNgGaZjsBUU

https://www.int.washington.edu/users/mjs5/Class_560/lec560_3/node2.html

https://hal.archives-ouvertes.fr/hal-01655838/document#:~:text=The%20pion%20exchange%20is%20the,energy%20%5B1%2D6%5D.&text=The%20confinement%20of%20the%20quarks,is%20just%20the%20dynamical%20mass.

https://www.merriam-webster.com/dictionary/pion

http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/hadron.html

https://en.wikipedia.org/wiki/Pion#Basic_properties

https://en.wikipedia.org/wiki/Goldstone_boson

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