You’re probably familiar with the Standard Model, a theory of fundamental particles and how they interact. These particles have counterparts that are mirror images or opposite charges or both, but in the 60s, we discovered particles that were flipped image and charge versions of each other, didn’t always behave, how we expected. We’ve since adjusted our expectations but even so, some of these particles and still behave in a way, we can’t explain. It’s what’s known as the strong CPE problem, and it’s a glaring flaw in the standard model. Dark Matter TV series
In order to understand the strong CP problem there’s a hierarchy of terms we need to make clear so we’re all on the same page. First up, we need to review the four fundamental forces, they are gravity electromagnetism, the weak nuclear force, and the strong nuclear force, with the exception of gravity these forces are mediated by particles in the standard model called bosons. The way these forces affect decaying particles starts to get complicated when we talk about symmetry.
Imagine an unstable particle that through an electromagnetic interaction mediated by photons decays into daughter particles. If you were to take that unstable particle and flip its charge, what’s known as charged conjugation or just see the charge flipped particle undergoes electromagnetic interactions in the same way as anti particle, the decay happens at the same rate, and with the same properties, meaning electromagnetism has what’s called see symmetry.
The same is true if we were to take that unstable particle and flip, all its spatial coordinates to make a mirror image of it, what’s known as parody or p. a mirror particle will also undergo electromagnetic interactions in the same way, or symmetrically to its regular self.
So electromagnetism has peace symmetry. And finally, electromagnetic interactions are the same whether we’re going forward in time, or back, so they exhibit t symmetry. They also are symmetrical with any combination of C, P and T, even all three together. Dark Matter TV series
So if you have a charge flip mirror image of an unstable particle undergoing an electromagnetic interaction backward in time, you still know what you’re going to get. Simple, right. Catch your breath let’s all take a minute to sit with this new information, because I think you know what’s coming next. That’s right. It gets more complicated. If our hypothetical unstable particle were instead to undergo radioactive decay mediated by the weak force than its mirror image version wouldn’t behave symmetrically every time it would violate piece symmetry.
This was first observed in 1956, back when we thought parody conservation was the law. So, you can imagine, it was quite a shock when scientists observed two arrangements of cobalt 60 became differently, since then it’s been observed that weak interactions also violate C, and T symmetry, and any combination of any two, though not C, P and T, all together. So, after reworking the math, the Standard Model today, allows for weak and strong interactions to violate all symmetries except CPT all together, which gives rise to a new problem we’ve observed weak interactions that violate CP symmetry doesn’t happen often, but it does happen nonetheless.
In fact, it happens a lot more than we’ve seen charged parody violation in interactions mediated by the strong force. We’ve seen that a grand total of drumroll please know times. Not one’s kind of disappointing isn’t it. The fact that the strong force should violate CP symmetry but hasn’t as far as we know, is called the strong CPE problem, but in science the unexplained is where the fun begins. Because the strong C,P problem is such a mathematical improbability, we think there must be something else at play here in the 70s scientists Roberta Pichai and Helen, Quinn propose that maybe there’s some undiscovered brand, like, a field that inhibits strong CP violation. If this field exists, then there should be a particle called an axiom to go with it. Dark Matter TV series
AXION should be charged, very light particle that’s hard to find, and doesn’t interact with anything except through gravity. Sounds like another candidate for dark matter to me, and indeed since the 1980s, scientists have been hunting for axioms in labs, as you’ve guessed, they haven’t found them yet, but they’re still looking for like the ADM x g to experiment axioms are not the only possible solution to the strong CP problem, and when we eventually do figure out why this expected unexpected event isn’t occurring. It’ll be exciting to see where physics takes us Next is the search for axioms and their relations dark matter has piqued your curiosity.