In atom spectrum, such as for hydrogen, there are states of 1s, 2s, 2p, 3s, 3p, 3d, etc. There are no 1p, 1d or 2d, 2f. Simply because n= n_r + L +1. So the maximum of L is n-1. But when I read articles talk about meson, they list meson states of 1p, 1d, 1f, etc. Such as in the article “Quark model” in the PDG report. What does these states come from? I am sure they use n ^(2s+1)L_j, and not the (n_r L), because they do not say 0s state. So what’s my mistake? Don’t meson has same rule of n= n_r + L +1?