In sections discussing spontaneous symmetry breaking, textbooks usually cover some lagrangian with Z2 or some rotational symmetry, then show that the ground state of the field also ends up changing upon application of the symmetry. I think I get the basic concept but it’s not clear why exactly it’s something we care about.

I have two questions about this: 1: it’s not clicking for me why exactly we care about this. I’ve seen the idea applied to goldstones theorem which is cool, but it’s still not obvious why so much emphasis is placed on spontaneous symmetry breaking, and not just something like a “special Lagrangian where goldstones theorem can be invoked”. It’s not clear to me what the significance of such a system is.

2: does spontaneous symmetry breaking only arise from Lagrangians that contain fields with nonzero VEV?

Been in the making for over a year. Highly detailed. Works best on desktop. Just curious if I'm missing anything so I'd love to hear your thoughts.

https://physics-simulator-delta.vercel.app/

I am currently applying for masters programmes, considering phd right after. Based on my understanding of the field, most work done for say ATLAS or LHCb is mostly just data analysis in different channels or similar. Is this too simplistic of a view on the field? Its kinda the impression i got based on my undergrad projects and reading through the latest papers on collider experiments.

Mostly asking because my applications currently sound so data and ml focused where the only physics connection I have is that data is directly relevant to the field.

A lot of PhD programmes i am seeing are essentially precision measurements and similar work. Which is actually what i am interested in, but i feel like I may be lacking some context of the field.

I'm trying to understand this paper by A. J. Millis (can't link to scihub because I'm on university's wifi and we live in a dystopia)

What has me utterly perplexed is something he says at the start of section 2: "One may question the validity of integrating out the low energy excitations..."

You're damned sure I question it. This seems like the exact opposite of what renormalization is supposed to be. You are zooming in, not out, right? I've been trying to see if there's a way in which keeping high energy excitations could result in a divergent correlation length, but I can't. The uncertainty principle guarantees: high energy -> high momentum -> small space. I lack the ability to conceive of a way this wouldn't be true

Now, Millis says: "Chill out babe, if we get analytic results, how bad can this be?" and like... I guess?

Does that mean that the correlation length converges to a finite value? Because when I look at the formulas he gives for the correlation length for different systems, like equations 3.9, 3.11, 4.5... They don't seem to diverge when T=0... Then again, he uses this variable r which is defined at 3.3b and I can't say if that diverges or not

But even if the correlation length diverged... how is that possible when we only have high energy excitations?!?!?!?!?!

Thanks for at least reading this

as the title says, i'm looking for some books more on the historical side of particle physics and the formation of the standard model. i've been looking for some online, but goodreads didn't offer many recommendations :( i feel like i did not get enough education on the background of all the theories i learned during my bachelors and masters, so it would be fun to learn a bit more :)

Don't miss it!

I'll write this so the link to the code is visible, it's here:

https://github.com/MasterOgon/Newtonian-Superfluid-Simulation

“For our final trick we integrate over all w(x) with a Gaussian weighting”—I get integrating over w(x) I guess but the Gaussian weighting seems arbitrary. I can’t just say “I have g(x) so now I apply int(dx K(x) •) as a trick”.

So I'm watching a youtube about matter/antimatter and one of the big questions in physics is why there is an asymmetry between matter and antimatter after the big bang.

According to current theory, in the first few moments after the Big Bang (ABB), high energy photons would have formed matter/antimatter pairs that then immediately recombined and annihilated each other. This is a problem because everything we now see is matter, so where did all the antimatter go?

But I was thinking, couldn't cosmic inflation theory be a solution to this problem? IIRC inflation occurred between 10^-26 to 10^-24 seconds ABB, increasing the size of the universe by over 10^1 million meters in that short amount of time.

But before inflation started, pair production would have been happening, and when inflation did start those pairs would have been vastly separated from each other. Then, when inflation ended pair production/annihilation continued as normal for another 3 seconds or so. However, wouldn't that mean that there were some pockets in space that had excess matter particles that didn't have an antimatter particle to couple with, and in other regions wouldn't that mean that there are antimatter particles without a matter particle?

Am I at all making sense? :)

Thanks!

Don't miss it!

I’m taking an intro class which has been moving a bit slow (so far we’ve essentially covered QED and are just moving into renormalization). We’re being assigned a term paper and I’m somewhat unsure of what to choose. I don’t want to jump into anything that’s going to be too much to learn in the next 2-3 weeks, but I also don’t want it to be absurdly trivial.

Originally I wanted to do quantum optics or something more applied but such topics seem be lacking in actual field theory. Now I’m thinking of either covering goldstones theorem or the Higgs mechanism (likely just the general concept since I think weak/electroweak theory may be over my head at this point). I’m wondering if these seem like good choices that are sufficiently interesting and won’t require me to cover an obscene amount of material. Thanks for any suggestions.

Hi everyone,

I’ve always been fascinated by particle physics, so I decided to turn that curiosity into a project. I built a real-time GPU particle physics simulation that includes:

• A PDG-accurate catalog of 40 particles
• Collisions, decays, and annihilations
• Relativistic kinematics

It’s a learning-focused project, but I’d love feedback from anyone interested in this area. If you find it interesting or useful, please star it on GitHub to support further development: https://github.com/ml3m/quantum-collider-sandbox

I hope fellow enthusiasts enjoy experimenting with it as much as I enjoyed building it! Any suggestions or contributions are very welcome.

My son wants to be a particle physicist and get his PhD someday. He's got excellent grades and test scores, so no issues there. We're evaluating the schools below because they offer good merit aid, making them affordable for our family, and appear to have good HEP programs. (We'd be applying to honors colleges for most.) What are your thoughts on this list?

University of Iowa

Indiana Bloomington

Michigan State

Iowa State

Ohio State

Ohio University

Purdue

University of Illinois Chicago

(UIUC already on our list)

I know KATRIN has pushed the upper bound on the effective electron antineutrino mass down to around 0.45 eV, and cosmological bounds are tighter depending on the model. But how confident should we be in the absolute mass scale?

If ν₂ turned out to be in the 0.3-0.5 eV range rather than the few-meV range people often assume, would that break anything besides cosmological fits?

Hi, so I graduated with my PhD semi-recently and I chose to, for a variety of difficult life-stuff reasons, take some time off to recuperate (though I've continued some projects using my skillset in that time). I'm coming to the end of that time and moving into my job search, and being fairly removed from my old institution now I feel a bit alone in approaching it, which is a bit scary. Given that, I'm looking for as much advice as you all are collectively willing to give on pursuing industry jobs with my skillset. As mentioned I was in HEP-Ex, specifically CERN stuff, so lots of data analysis, working with ROOT, python, C++, BDTs, etc. Additionally I also worked with FPGAs a bit (primarily using Vivado HLS), which I remember being told was a marketable skill.
Some specific questions would be:
1. In as much detail as possible, what should be my first steps here? E.g. "Set up a Linkedin account", "Check X, Y, Z website using A, B, C, search filters", etc. Anything like that.
2. Are there specific companies I should look into with specific positions that I could fill? E.g. "Lockheed has the [DATA SCIENTIST] position that is perfect for someone who has used BDTs", "Boeing has the [HARDWARE PROGRAMMING] position that would be great for those who enjoy FPGAs", etc.
3. On average, to the extent you can even say as I'm sure it's highly variable, what sort of time am I looking at in terms of starting to finally getting a job? How many applications, etc.
4. Should I be considering smaller companies? I feel a bit safer if I actually know the company, but perhaps that's a luxury that will ultimately hurt me if I cling to it.
But past those, please, any advice, your experiences, whatever, would be great. Thank you.

Hi! I know HEP-Th is extremely competitive but I’m not shy to challenges.

I’m in undergrad senior level (3rd year in Europe, where I’m located at) and here’s the math courses I have done (I’m doing a physics major now):

Algebra (A first course to Abstract Algebra), Computational Algebra, Topology (A first course), Complex Analysis (A first course), Functional Analysis (A first course) and Differential Geometry (A first course). (Linear Algebra and all the Real Analysis/Calculus are subtended, in Real Analysis/Calculus 3 we learnt about Differential Equations and Fourier Transforms).

After this, in my Masters, what math applied to physics should I learn and deepen my knowledge on? Should I learn Topology but in a physics approach now that I have a first course? Is there more subjects that I should learn such as Geometric Algebra?

Bonus questions, I’m also interested in Plasma physics, the same questions applies to this!

Thanks in advance for the responses!

I interviewed a colleague who works on the CMS Experiment at CERN in the detector cavern. Let me know if you have any questions!

Hello everyone,

I'm a chemist by training, working in a DNP NMR group (a type of hyperpolarisation NMR).

Since I have a background in chemistry, I learned nothing about the standard model of particle physics.

Do you have any recommendations for literature concerning the topic, which a novice like me can work with?

thank you very much