Wow! What a rabbit hole finding a proton is not just 3 quarks!.

Suggesting these 2 articles:

1] Experimental results of proton collision as of 2013 (3 quarks is an observation, but for low energies) :

https://physics.stackexchange.com/questions/81190/whats-insi...

2] Another article from the same author (Matt Strassler). Suggesting to read his answers for the comments of: Harry Bostock, Bob Anderson, and the 2 top comments of "aa. sh." (for more history and Neutron decay)

https://profmattstrassler.com/articles-and-posts/largehadron...