# Can sea quarks change the (iso)spin of a hadron?

A hadron is made up of valance quarks ($qqq$ in the case of baryons and $q\bar q$ in the case of mesons) and sea quarks ($q\bar q$ pairs). Since all internal quantum numbers of quarks and anti-quarks are opposite, sea quarks cannot contribute to e.g. the overall strangeness or baryon number. That been said, the spin of a quark is equal to that of it's anti-quark. Thus if the $q\bar q$ pair are in a triplet state one would expect the possibility of sea quarks contributing to the overall spin of the particle - but since (as far as I know) we get only $J=0$ and $J=1$ mesons this does not appear to happen. Thus my question is:

Can sea quarks contribute to the overall spin (or even isospin) of the hadron? if so why and if not why?

• Would you consider a decay like $\Delta\to N\pi$ a change in isospin? The total isospin is conserved, but it leaves the nucleon and is destroyed by the non-strong decay of the pion. – rob Mar 29 '17 at 17:05