or you could just link to the actual press release from Actual CERN?
https://home.web.cern.ch/news/news/physics/symmetry-between-...
https://home.web.cern.ch/news/news/physics/symmetry-between-...
So I expect in this cases the guesses were wrong and the Standard Model will manage to explain that as well.
It's an old term that was created before they knew that up and down quarks existed.
Personally I find the term outdated because there are 4 other quarks, and isospin only talks about two of them.
> Isospin is also known as isobaric spin or isotopic spin.
Supersymmetry: https://en.wikipedia.org/wiki/Supersymmetry
Does the observed isospin asymmetry disprove supersymmetry, if isospin symmetry is an approximate symmetry?
In its current agreed upon form it's just SU(3)xSU(2)xU(1). This gauge symmetry defines the lagrangian, which has 19 parameters to be determined by experiment.
It's true that this isn't the whole story (dark matter etc), but these symmetries are physically motivated and their predictive power is pretty amazing (the QED part is CORRECT as far as any experiment has been able to check so far).
So it's not quite as bad as "you just hit the model until it says what you want it to say". It's more "your shortcut broke so take less of a shortcut and you may discover that the standard model worked better all along than your shortcut". Which, again, has already happened multiple times.
In fact it is quite frustrating to physicists that the standard model always wins these fights. They'd love for it to break in some concrete manner, which is why they're always going on about this break or that break. As it stands now, in some sense, every time the standard model is vindicated it's a worst-case scenario for particle physics. It's not like there's a cartel trying to defend it... everyone would love to be the one who definitively broke it! It's virtually a guaranteed Nobel prize.
??? Where does empiricism come in? Surely you need some kind of data to feed even raw assumptions. Maybe I'm just misinterpreting how "first principles" is employed here.
1. Hey these particles are interacting with each other (e.g. they attract each other, they repel each other, they combine or split apart into each other, etc...)
2. I have measured something about this interaction (e.g. how fast, how far, how likely, etc...) to within a certain degree of accuracy
Put them together and we have a sparse noisy list of forces, and a list of constants.
Then we come up with theories to explain and reduce the data to their simplest components.
Those theories occasionally spit out that there should be an interaction we haven't seen between some particles yet or a more accurate picture of an interaction we have already seen and we can run some experiments to see if the theory holds true in practice.
We can then check how well those theories work by their predictions.
- Gravity is just varying amounts of positive attraction over unlimited range (i.e. just a positive integer).
- Electromagnetism is varying amounts of positive or negative attraction over unlimited range. (i.e. just an integer)
The problem with strong interactions is that they get messy really fast. The energies and interactions involved are crazy.
- We have the quarks (which are the fundamental matter particles that the strong force interacts on)
- We have the gluons (which are part of the strong force itself)
- And the strong interactions: which are actually 3 different amounts of positive or negative attractions that must all balance out (i.e. a whole bunch of numbers), but they get stronger as they get further away to the point that new particles can be created to reduce the range between any two particles, oh and the gluons can also interact with each other complicating matters further.
But the problem with SM is that when one deals with strong interactions, nobody so far came with good ways to calculate things. For example, in theory the mass of proton can be derived. But in practice it is not. So one uses that as an extra parameter and tries to use that to constrain calculations in other areas.
No, it isn't; those are actual quantum numbers of the electroweak interaction below the symmetry breaking energy (the other such quantum number is electric charge).