QCD Sum Rules for $Σ$ Hyperons in Nuclear Matter

Abstract

Within finite-density QCD sum-rule approach we investigate the self-energies of $Σ$ hyperons propagating in nuclear matter from a correlator of $Σ$ interpolating fields evaluated in the nuclear matter ground state. We find that the Lorentz vector self-energy of the $Σ$ is similar to the nucleon vector self-energy. The magnitude of Lorentz scalar self-energy of the $Σ$ is also close to the corresponding value for nucleon; however, this prediction is sensitive to the strangeness content of the nucleon and to the assumed density dependence of certain four-quark condensate. The scalar and vector self-energies tend to cancel, but not completely. The implications for the couplings of $Σ$ to the scalar and vector mesons in nuclear matter and for the $Σ$ spin-orbit force in a finite nucleus are discussed.