Ohhh no, don't blame me for writing "Stable or Down quark + Positron + Electron neutrino." That's copy-pasted from Wikipedia! Hahah, it could be that your information is outdated then. Opening a textbook or listening to a lecture is only helpful if it is impossible to do an experiment. Which it is for us, in this case.
Either outdated, or Wikipedia is simply wrong. Dumbed down too far to report accurate information on highly technical topics. Which I can believe. I can believe any source is wrong. I have less faith in human knowledge than many people do, even when it comes to scientific experimentation and theory.
What seems interesting is that Wikipedia says that Down Quarks decay into "Stable or Up quark + Electron + Electron antineutrino" while Up Quarks, as we read, decay into "Stable or Down quark + Positron + Electron neutrino."
That implies that it's not so much that they're decaying, but that they're ...switching their flavor? Due to the polarity being reversed. Maybe? When it comes to sources, I have no ability to go further than the main pages of Wikipedia. I don't know where to find out who even wrote that right-hand sidebar that includes the "Decays Into" note.
But on Wikipedia at least, every flavor of Quark DOES indeed have the same right-hand sidebar, and they all list a "Decays Into" area, and they seem to go from highest mass to lower mass, with a percentage chance of skipping a step. But a low percentage chance.
Perhaps you're using information that's meant for another area of testing. For example. a quark -on its own- may do exactly what you said. But a quark that resides within a stable hydrogen atom, for example, might decay how I listed. But I'm not a professional physicist. Only a hobbyist.
I have tried to find "Stable or Down quark + Positron + Electron neutrino" on Wikipedia but I cannot. Do you mind showing me where you have seen this. I can guarantee you that it is incorrect and I would like to understand in which context you have read that. In the current Wikipedia page on quarks, this is not there. This page is by the way quite accurate, and contains 104 references supporting the text. This is what makes a page, even a Wikipedia one, trustable: the bibliography.
I can finally guarantee you that my information is not outdated. It is not only in agreement with 100 years of experimental facts in particle physics, but also with a century of theoretical developments. Not contradicting data and agreeing with theory is a sufficient proof of the correctness of the information, IMO. On the contrary, what you write simply violates the most golden rule of physics that has been testified by all experiments undertaken so far: energy and momentum conservation.
Then, I must that that you managed to strongly shock me with the following sentence.
This was dreadful to read. Textbooks are very useful, as they offer the possibility to learn about a given domain (that could be science or anything else). In physics, current textbooks cover both theory and experiments, and they summarise pretty well hundreds of years of research. Saying that they are useless is the same as saying studies are useless or even that science is useless per se. I am sorry to say that I strongly disagree with your statement, that even makes me sad.
As a counterexample to what you claimed, we can see that at our human level, Earth appears flat (I mean, when I walk in the street or look through my window). However we know it is not flat at all. It is thus not because I can experience something that I don't need to rely on literature. On the contrary...
Yes, quarks can change flavour (there are 6 quark flavours) during any given process. The occurrence of a given quark flavour changing processes depends on the energy of the initial state, and the different quark species entering into the game. However, such a process is always embedded in a hadron-level proces.
I am finally unsure about what you meant by polarity here. It is more a matter of quantum field theory computations.
No there is NO decay information on this Wikipedia page. Which one do you use as a source? If you don't specify it explicitly, I am afraid that I won't be able to help. My purpose here is only to share accurate, information and helping. Nothing more. This is the reason why I comment a lot any blog discussing particle physics on Hive. I like to bring precision and anecdotes.
I do use the relevant information here. A quark will not decay as a free quark does not exist. Only hadrons (for instance a neutron) do. Note that this has nothing to do with hydrogen atoms, that are stable (which is a good news as more than 90% of the visible part of the universe is made of hydrogen).
As a side note (since you implicitly seem to ask), I am a professional physicist... My field of expertise is theoretical particle physics.
Oh, I thought you had been on the same pages I had been on.
Each flavor of quark has its own wikipedia page.
https://en.wikipedia.org/wiki/Top_quark
https://en.wikipedia.org/wiki/Up_quark
There is a sidebar on the right side of each and every quark flavor page.
You can follow the trail from Top_quark all the way to Up_quark.
Wow!! This is just completely wrong! It seems that they (I have no idea who "they" are) have misread their references! Now I understand why you have written what you wrote. However. this is incorrect. The general page on quarks is instead correct, and I can also recommend good books if you are interested.
In a few words, the thing is that the top quark is the only one that can decay. It can decay through three possible channels, leading the production of a W boson with a bottom quark, or a down or a strange quark (the last two being rarer).
The other quarks do not decay. They form first composite states named hadrons. Then, hadrons can decay into each other, and you have many many decay modes depending on the quark content of each hadron. At the end, those decays involve the conversion of one or some of their internal quarks into other particles.
I hope this clarifies.
Cheers!