Hi people, I've read some articles about the calculation of mass spectrum. But I'm not clear with this concept. Can we calculate theoretically the mass of quarks. If yes, how? because we never see an isolate quark. Off curse experimentally we can. And my second question is about the mass of mesons ,if we know the values of single quark mass we can calculate the mass of hadrons, if we don't know how can we calculate the theoretical values of hadron mass. THANK YOU !!!