Particle Physics Explained Visually in 20 min | Feynman diagrams

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If you didn't understand this video, these may help:
0:00 - Intro & Fields
2:22 - Special offer
3:09 - Particles, charges, forces
6:32 - Recap
7:13 - Electromagnetism
10:04 - Weak force
12:19 - Strong force
16:53 - Higgs
If we generalize the concept of bosons interacting with particles, we can get all fundamental particle physics. Complex math, but physicist Richard Feynman came up with a simple way to view these interactions - Feynman diagrams.

The 12 fermions are depicted as straight lines with arrows in the diagrams. The arrows represent the “flow” of fermions. No two arrows point towards each other. If time is in the x direction, then fermion arrows going forwards are matter particles, and those going backwards, antimatter particles.

All 6 quarks have color charges. All particles with color charges interact with the strong nuclear force. Quarks also have an electric charge, so they also feel the electromagnetic force.

Leptons can be divided into the electron and its heavier cousins, the muon and tau particles. These all have electric charges but no color charges. Neutrinos do not have a color charge or an electric charge, so they are not affected by the strong and electromagnetic forces.

All fermions carry something called weak isospin. This can be thought of as the “charge” of the weak force. It can be +1/2 or -1/2. All fermions interact with the weak force. But weak isospin can also be -1, 0, and +1 – the W- boson has a weak isospin of -1, W+ has +1, Higgs has -1/2, and Z boson and photons have a weak isospin of 0. Note that this zero is not the same has having no isospin. Everything in the standard model has a weak isospin except gluons.

The weak force has the power to turn one particle into another particle. It is the only force that can do that.

To recap, quarks interact with all forces, electron like particles interact with electromagnetism and the weak force, but do not interact with the strong force. Neutrinos only interact with the weak force and nothing else. Only quarks and gluons carry the strong force. Higgs bosons do not interact with photons or gluons. They confer mass to fundamental particles, so all fundamental particles with mass interact with Higgs.

The simplest force is electromagnetic which interacts with quarks and leptons. Repulsion is depicted in Møller scattering. Attraction is shown in Bhabha scattering. When electrons and positrons are near each other, they can annihilate or attract each other.'

Weak force is felt by all of the standard model particles, except gluons. W-boson can do something very special. They can change the identity or flavor of the particle - a neutron to a proton. We probably would not exist without it.

Z-boson has no electric charge and can mediate interactions with electrically neutral particles like the neutrino and the Higgs.

The strong force is the most complicated mathematically, but since it only relates to quarks and gluons. A pair of quarks can change color. This happens all the time inside protons and neutrons, and is the glue that binds the quarks together.

Because gluons themselves contain color charges, they also interact with each other via complicated diagrams. This is what flux tubes are made of. These tubes are formed when you try to pull quarks apart.

Mesons are formed when a quark tries to leave a nucleon. These mesons are a combination of a quark, anti-quark pairs which mediate the strong force between protons and neutrons.

Pi mesons exchanges colors and quarks between protons and neutron. This is what keeps them glued together. Color charges must be conserved. Either red, blue, and green must combine, or color anti-color must combine to form a neutral color charge.

The most prominent process used at the Large hadron collider to make a Higgs boson is called the gluon fusion process. During high energy proton-proton collisions, two high energy gluons can be produced. Strong force interaction can turn these into top quarks which fuse together via a loop of top quark, anti-top quark creation and annihilation. The energy of this can create a Higgs boson.
#particlephysics
#fundamentalforces
When particles decay, they tend to decay into the next highest mass particle.

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If you're new to this topic, or want to review some of the preliminary background, these videos would be helpful:
For more details on QCD and QED:

ArvinAsh

This is an excellent example of what I want: "above my head, but not out of reach". Thank you.

WilliamDye-willdye

Anyone who can turn math into pictures is unequivocally a science rockstar.

Just_Sara

I'll never get tired of saying this:
Thank you Arvin and your team behind all these amazing videos, you're the best.
I have learned a lot with you.
Many blessings my friend

rodnyc.

If Richard Feynman could see this video he would be so happy!
thank you.

mahmoudjbely

I have never liked physics until I found this channel.
Thank you Arvin.

MoReal

I will never be the next Einstein. I will never be the next Feynman. I will never be the next Arvin Ash. But I *will* be the next commenter to thank you for this.

christianlibertarian

I love you so much, man, and I love the way you explain, you sound like a great artist like Robert De Niro or Al Pacino, I often don't press skip ad to support you.

omargaber

I want to become a particle physist and this video was very helpful sir.. Thank you!!

sureshms

So if i understand correctly...

The down up anti color charge isospin with down left-right strong anti pi meson +5/6 color charge interacts with the higgs anti photon pair and anti blue anti green positron which causes a change in anti-momentum forming a new anti-anti particle with charge equal to 3 quarts + 1 pint sugar plus an anti mexico-meson pair.

OmegaFalcon

Arvin, I'm gonna frame this as the quote of the year:

6:10 *"It's a stretch to call the Weak Force a **_force._** It's more like a **_power._** The Weak Force has the **_power_** to turn one particle into another particle."*

That is the best, most succinct explanation of the Weak Force that I've ever heard. Accuse me of seeking confirmation bias if you will, but it ameliorates the biggest unease I've had about calling it a "force." Ever since my school days, to me, _force_ in physics is anything that can cause acceleration. Or, to use General Relativity terminology, anything that can change the straight-line trajectories of particles in space-time.

I'm also happy that you reaffirmed gravity's status as a force. The fact that it's not included in the Standard Model doesn't nullify its ability to change trajectories.

Of course, I have misgivings about calling the Weak Force a _power_ as well, since _power_ too has a technical definition in physics—the rate at which _work_ is done. I'd probably go with "... *ability* to turn one particle into another." There, last nit picked and done.

nHans

Superb!!! Animated Feynman diagrams are GREAT!!! Please do more like these, but with many dots flowing through at once, faster.

erebology

Im 11 years old and am still fascinated by this. Keep it u Arvin! Merry xmas!

lindapunches

it is really astonishing, seeing a person on youtube who can explain complex physics very well without introducing its love from india..

nidhilok

This is great. I gotta say though: the uninterrupted powering through of the strong force section is what I want to show people who ask me how particle physics works to get them to say "ok nevermind" lol.

llampwall