Abstract :
We compute the finite temperature pole mass shits of the octet and decuplet baryons using heavy baryon chiral pertur-bation theory and the 1Nc expansion, where Nc is the number of QCD colors. We consider the temperatures of the order of the pion mass mπ, and expand truncate the chiral and 1Nc expansions assuming that mπ ∼ 1Nc. There are three scales in the problem: the temperature T, the pion mass mπ, and the octet-decuplet mass difference. Therefore, the result is not simply a power series in T.
We find that the nucleon and Δ temperature mass shifts are opposite in sign, and that their mass difference changes by 20% in the temperature range 90 MeV < T < 130 MeV, that is the range where the freeze out in relativistic heavy ion collisions is expected to occur.
We argue that our results are insensitive to the neglect of 1Nc− suppressed effects; the main purpose of the 1Nc expansion in this work is to justify our treatment of the decuplet states.
