What is a quark?
Gordon L Kane, Malcolm J. Perry · International Journal of Modern Physics A · 2015
We are used to thinking of quarks as fundamental particles in the same way we think of the electron, or gauge bosons, neutrinos, leptons. In strong theory, these objects are unified with gravitation and the physics of spacetime into what is hoped to be an ultimate theory, string/M theory. The string/M theory paradigm completely changes the way we think of the so-called elementary particles in quantum field theory.