Hi. I know ARPES is supposed to show the k-space resolved density of states within the BZ. But sometimes the correct BZ is not so obvious. Take for instance La2Mn2O6. If you ignore the magnetism, then you would choose one BZ and get one set of bands. If you now turn the magnetism on, and continue to use the same zone, k would no longer be a good quantum number and the bands would show some disperson. This is apparently what is seen in the ARPES experiment. However, I might have chosen the double my unit cell to incorporate the lower periodicity due to the anti-ferromagnetic ordering. Then my BZ would shrink, k would again become a good quantum number, and there would be many more bands than in the original picture. What determines which one ARPES sees?