Borel sum rules for octet baryons in nuclear medium

Borel sum rules are examined for octet baryons in the nuclear medium. First, it is noticed that in the medium the dispersion relation is realized for the retarded correlation ΠR(ω, q2) in the energy ω. Then, ΠR(ω, q2) is split into even and odd parts of ω in order to apply the Borel transformation. The obtained Borel sum rules differ from those of previous works. The mass shifts of octet baryons are calculated in the leading order of the operator product expansion with linear density approximation for the condensates. It is found that both scalar and vector condensates of the quark field, and , induce attraction to the octet baryons in the medium in contrast to the results of previous works. It is also found that |δMN| > |δMΛ| > |δMΣ| ∼ |δMΞ|. The absolute values, however, turn out to be one order of magnitude larger than those empirically known if a Borel mass of around 1 GeV is used in the present approximation. (author)