What IS a Cross Section pt. 2: Differential Cross Sections in Particle Physics
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- Опубліковано 19 вер 2024
- Today I discuss how the interpretation of the cross section changes when we both turn on interactions and quantum mechanics. I discuss the importance of the differential cross section in particle physics with a couple examples, including how they can be used as evidence for the existence of new particles.
Some nice info on classical cross sections:
web.physics.ucs...
"Source" of ATLAS data (the links to helpful papers are here):
atlas.cern/upd...
Small correction: The Higgs mass at ≈125GeV was not predicted by the Standard Model but is actually a fit result from the measurement data. There were some contraints on the Higgs mass based on other experiments but no actual prediction.
Thanks for pointing that out!
OP,what do you mean by "fit result"?Sorry,1st yr undergrad here
goktrenks when they draw invariant mass distribution(aka plot) the saw some pike. This pike in mass corresponds to Higgs mass. In order to get this value they get some functions with parameters and tried to fit aka find values of parameters so that function looks like original distribution. One of the parameters of this fit function corresponds to the mass of the Higgs. en.wikipedia.org/wiki/Curve_fitting some wiki article about that
P.s. sorry English isn’t my native language.
@@ozymandias3303 Thanks!
What’s going on smart son! Another great video ~ Mom💕
Hi Mrs. Dotson! 👋 Just wanted to comment that you are a great mother for following and supporting your son's videos so much. I wish my mom cared about my stuff like that 😅
kindly read everything from this site to know about the absolute truth islam -onereason.org/
@@laRa-zg8ys fuck off please
@@laRa-zg8ys No one whats to, fuck off
@@laRa-zg8ys this is physics, not religion, so as the 2 people above me said, get ur ass outa here
“If you think this graph looks gross, just imagine calculating it” - I felt that on a deep level
Sami Lamby want sum polish hotdogs?
i dont even understand this and i enjoy it.
I can relate....
Polish hotdogs?
I feel the same 🔥😂🔥
xBulletBoi bro same haha. I’m just a computer engineer going for a comp sci masters 🤷♂️
Keep at it. Eventually you will.
Andrew you probably won’t see this but I just started my undergrad as a physics major in part because of you. I’m scared but excited wish me luck!
Yoo same dude! Good luck! I hope you do well and enjoy it.
Wow best of luck!
haha another string theory enthusiast...
I’m doing physics with astrophysics and I’m dead scared
Honestly. I'm lowkey deciding to switch to physics because of a couple reasons but his teachings on physics is definitely one of them
4:22" allow me to demonstrate" I thought he was gonna throw the cat on the wall
Omg I love that!
Me too
Andrew isn't alinity so I wasn't too scared
I just want to comment to Andrew that he inspired me to persue physics. You are my physics hero, thank you, you mean the world to me.
Never stop posting you inspire more people than you could know!
:) thank you for the nice comment!
Hey man, for me it's such a great feeling to learn about this at an early stage. Great to see you back with the lessons!
You’re so good at making understandable analogies, relating abstract mathematical ideas to physical interpretations. Thats a valuable skill
Thanks a lot!
Hi Andrew!
I had recently taken particle physics before I graduated as an elective. The cross-sections part had me very confused but you explained it a lot better than my teacher!
imagine you are from sub continent and studying particle physics in Italy and your teacher have that accent which is as hard to understand as the cross section. :(
Dude, I just came out of my QM1 class and didn’t get this, you’re a hero
some days when i’m sad i’ll binge your videos because i love physics, and then i realize i barely know what you’re talking about. but every time i hear, “what’s goin on smart people” i think, “he...he said i’m smart🥺”
I'm in Physics 2 right now and the fact that I actually know a couple of things you're saying and understand it is amazing. Even if it's just the simple pieces for this video.
I feel like u make these types of videos not only to let others needing help with these things but to also understand it further urself. Good job, keep it up
Hey Andrew I just fell on your channel and it's just so amazing!! Your explications are so clear it's so nice. With my 15 years old (16 tomorrow haha) and the fact that I'm not an English native speaker at all, I can't understand everything for sure, but I'm still so happy to learn about science and physics so thanks from Québec for your wonderful work!
This is priceless knowledge for free. Thank you Papa Dotson.
Awesome video, Yep would be great if you can make a follow up video to actually calculate the probabilities using the Feynman rules etc
im so thankful people like you exist, we need y'all
As a physics major, i'm glad i found this channel, it makes me normal i like it 😂
Thanks for the video! This has been my research the last two years (Drell-Yan differential cross section for CMS); I'm glad to finally learn it!
Oh yeah I'm sure you have dreams (or nightmares) of them then!
andrews humour is the most underrated thing on the internet
Finally! Andrew uploads and it’s cross section part 2
This was great, keep making more of those.
your channel made me really interested in physics and potentially pursuing it as a career, very nice content. keep it up
I can't wait till I come back to these videos after 2 years at uni and understanding them. Gonna be so satisfying
Any video from you is good. Bring some more!
People always ask WHAT is a cross section, never HOW is a cross section. Good video Andrew!
Hey Andrew,
I was studying this for my thesis (just getting started) and I didn't understand anything until I saw your videos. It's amazing how you explain it and now I'm even more excited to learn. Thanks
Glad you found it helpful!
I'm interested in seeing how you would present the math
It'll definitely be a challenge to present it in a way that's not just vomiting P&S onto the whiteboard but I have some ideas.
Early thunbs up for your high aims presented as, "let's go, can't be that difficult"
Would love to see future studends coming to your lectures and say, "Professor, we saw your historic lectures!"
Omg welcome back! You haven't made videos in over a month!!
I discovered this channel today.. you are awesome! So nice to have found this, very early on in my PhD, it's a great support! :)
I’ve missed you dr Dotson that video was amazing. I would love to see the same video but in the math version.
Man im studying for a internship in introductory pertubative QCD, your explanation was very usefull!
Another videos in this direction would be nicelly welcoming.
Thanks a lot!
Now i feel happy.
Its been a long time.
Awesome video.
Nice presentation. I like how you show the creation of the Higgs boson! I, for one, would love to see you work out the math as well, that would be an interesting way to learn this! Thanks again for another great video!
I go to high school at the moment (and i want to study physics at the unoversity) but deep down i know that some day when i am going to struggle because of my classes and because i won't understand it, your videos are going to help me. Thank you.
particle physics is so difficult. great job explaining tho, I really liked the experimental data proving the higgs bozon towards the end. seeing the calculations I wouldnt understand much probably, but it could be entertaining.
I don't understand any of this but I enjoy Andrew's talking and the way he explains concepts. To be honest I'm still subscribed to help out our boy here.
Id love to see this. Havent gotten past basic particle physics so itd be cool to see some qcd and other stuff from the standard model
Please give more lectures of Quantum Field Theory
PLZ REPLY ANDREW
Hey andrew, we want to invite you as a guest for our virtual conference.
The other speakers in this conference are
Alexi Starobinsky, Cosmologist, Kavli prize winner 2014.
Jorge Pullin, Theoretical Physicist.
Dan Hooper, Cosmologist.
May I know how to contact you?
Hi,
my email is available on my about section. I haven't checked it in a couple weeks because I've been working on other projects, but now I have some time freed up.
@@AndrewDotsonvideos Hey, thank you for replying. I have sent you an email . In fact I have sent you a couple of times. The latest one would be the invitation for the conference. You must have received it from this email (physicsforever242@gmail.com)
@physics forever, im a research grad in cosmology. If i can also join you guys - ( anshul.verma690@gmail.com) . Ty
@@toxxikanshul OK, we have sent you an email
Eew Krauss is on the list
Great video! Great to learn about important aspects of particle and nuclear physics 👍
"Just imagine calculating it" - Well, considering I am working on my bachelor's thesis on numeric stability of multi-loop integrals, I felt that.
I would really like to see more on differential cross sections and how you calculate them
Andrew have you considered being a professor? Your videos are amazingly intuitive even for someone with a limited physics background.
Maybe one day!
Thanks for these great videos!
I'm doing my probset in QM right now... thank you for this video
Hi andrew i am your big fan
From india
I also want to pursue carrier in physics
Hey Indian
give me your contact number.
@@cricketkings3487 lol
@@cricketkings3487 give me yours too
Hey, ANDREW PLEASE ANSWER TWO QUESTIONS
1) Can you make video lectures on Optical Physics??
1) Are Walter Lewin classical Mechanics, Waves and vibrations, Electricity and Magnetism lectures enough for co-responding topics in Bachelor level Physics??
Well done. Very good overview!
Thanks a lot!
I am going to apply for my pg program in particle physics soon🙈 And I recently found your channel, you are LITERALLY what I aspire to be. Your videos just gave me an extra boost of confidence that yeaahh this is what I wanna do!! Thank you for your efforts ❤️
Also... Can you suggest me few topics I should have a good grasp over before starting with my pg in particle or theoretical physics? Both in maths and physics.
This was very insightful. (Spoiler alert) The Higgs was a really cool example. Thanks, Andrew!
Thank you!
Huh, I ended up watching the second video today already :D Nice video, looking forward to the next one :)
This is what I'm doing in my research right now! Just finished writing a program to calculate cross sections :)
Awesome! For what process?
@@AndrewDotsonvideos Inclusive electron scattering! I got a research assistantship from JLab this summer so I've only just started but it's been great so far. I'm looking at it at high Bjorken x values with different momentum and targets to study the electrons after scattering.
Gwen nice! I had a couple internships there as well. Who are you working with?
Andrew Dotson I’m working with the Niculescus! They’re my research advisors at my university. I was supposed to have a SULI internship this past summer but it got moved to next summer so we’ll see who I work with for that!
Thanks for great video and also for references
I would like to see a video about answering the question "Do you have to go to a prestigeous university to study physics?" More specifically to have the resources you need to become a successful physicist.
Yes please the maths behind differential cross sections.... I'm studying field theory and particle physics this semester.
Awesome. Would have been better two months ago when I was covering cross sections 😂😂
We were doing the math with no real reference point for what we were explaining with the math. Thanks!!!
also AnDROw what was the list of bad physics textbooks for? I was watin so eagerly for a vid on that or something..
I have an idea for it
Pls do a lecture on Dirac Hole theory and Dirac theory in electromagnetic field.
never clicked so fast !!
Wouldn't the 125 target energy be more akin to heavy element creation or a proton/neutron isotope instead of a fundamental particle given that it's clearly unstable at that energy density?
The Higgs energy state was a wonderful discovery, but I've always questioned it's true nature as a defined particle instead of a combination of quarks coming unglued through decay.
It cannot simply be something like a heavy nucleus because it has baryon number zero. But you are right, it might be not a "fundamental particle" (however that would be exactly defined in a quantum field theory), there are several "composite Higgs" theories in the literature. In the Standard Model, the Higgs is a fundamental field in the Lagrangian, but the S.M. is certainly not the last word on this...
Hey, great helpful video. Did you do a video on calculating the cross section for this type of decay? Would be super helpful for my thesis to further my understanding (specifically the gluon fusion resulting in the Higgs creation)
Why is mass frame independent? I though that as a particle approaches c its mass goes up to inf? Or is that just 1/0 math nonesense?
No. Mass never depends on your reference frame. Inertia increases as your speed increases, but that's because relativity shows that total energy contributes to the inertia of the system, not just the mass.
yess please do a video with the math!
Make special theory of relativity by the way I love physics and you
yeah, special theory for dummies, light clocks and space ships! no matrices. I second this! Peeps love those.
Hlo Andrew. How often do u think that your interest fluctuates from physics
Please make a sequel!
Hi bro, big fan of your shit, and got a bit of a request for u. I am 18 and going to study pure physics next year, could you make a vid or two on calculus in physics for those of us who found pre uni physics and maths a doddle but struggle with stuff like this because we just haven't covered the material yet. Thanks
All you physics guys there does anyone know what d(rho)/4pi represent?
Is there any way of knowing the out come of a particle interaction, or is the outcome also probabilistic?
That is the cross section. sigma(2p-> 4l) is a measurement of the probability that the outcome will be 4 leptons if two protons go in.
Love you Andrew, you keep me going and all your subscribers, hope you life keeps getting better (((((( : ♥️🎃
Is there going to be a part 3? I really enjoyed 1 and 2
Is this related to differential calculus, cos that's what I only know
a bit, yeah... :3
This is all very interesting, but I'm still confused what the Differential Cross Section actually means.
watch part 1
It’s the probability of measuring a certain process within a certain range of a kinematic variable such as solid angle or energy.
Andrew is great but he does not have control of DCS YET...neither do I.
SHOW US THE MATH! :D Theoretical physicist here! :D
please do a video of lie groups in standar model please please please and i really love your videos (i have 16teen)
Hello sir, I sent an email to you regarding the x-ray absorption cross section and fermi's golden rule could you please read through the email and make a video regarding that please.
I love the lecture videos!
Get a load of THIS guy
Bro i wana do p.hd in QM ,what do u think any pro tip
Good day, Doctor Dotson
He's gone full professor mode: "Just read Taylor " haha
I agree
As a medical engineer with no experience in quantum physics I came to better understand Compton scattering and the Klein-Nishina differential cross section and left with a headache.
what are you're social media handles?
I finally get it! Thanks 👍
0:19..yes quite quite
Nice
How it's going
I’m a freshman, I don’t understand anything yet I still enjoy HAHA
❤❤❤
Can you finish up your Phd and become a physics professor in Iceland?? (It pays well)
6rd
Where's Kelly?
what do you think about the QED renormalization?
That’s the only renormalized theory that makes sense to me conceptually
@@AndrewDotsonvideos Huh, how exactly does it make sense? ... :D "Look, it doesn't work, everything is singular. Oh look, if we use totally unrealistic parameters such as mass and charge, we get the regular answer!" The only "real" magic I see here is that this reparametrization works in every single case with the same reparametrized mass and charge. The "lets try different mass" thing is the voodoo part of magic :D And yes, this is then applied to everything, such as quarks as well. Yes, QED was kind of proven when the screening of charge was measured through fine structure constant... but.. it's all circular... of course it was "proven", all the parameters were chosen so to fit the experimental results, all but one experimental result -- the mass and charge of a free particle :D So... it proves nothing... Or, the asymptotic freedom in QCD, same thing, same problem... I don't know... It stinks. Chime in with your thoughts please if you will. Been reading about it a lot for last few decades, nothing makes it seem any brighter to me... Regards! o/
*me, who just got into college 2 weeks ago and just begun learning gauss's law watching this video* : ah yes electricity, i know a lot about electricity and charges and fluxes
When is the graphic tablet coming in?
Whenever it gets delivered!
next video: meme review?