Hypernuclear physics: A brief past and bright future

摘要

A primary reason for investigating the structure and reactions of baryon systemsis to achieve an understanding the fundamental baryon-baryon force in the realm of non-perturbative QCD. Few-baryon systems play an essential role, because one can calculate complete solutions to test a particular baryon-baryon interaction ansatz. Hypernuclei, exotic nuclei containing one or more hyperons (Y = (Lambda), (Sigma), or (Xi)) are crucial to this investigation, because they permit one to probe models based upon our experience in the nonstrange sector; they lie outside of the conventional world where our models were developed. That is, we can test whether our sophisticated models of the nucleon-nucleon (NN) interaction extrapolate successfully beyond the zero strangeness region in which the parameters were determined, or whether the models merely interpolate. The presence of the strangeness degree of freedom (flavor) adds a new dimension to our evolving picture of nuclear physics. We shall see that the physics of hypernuclei is both novel and puzzling, stretching our intuition and analysis capability beyond that developed during the more than half century that we have explored conventional nuclear physics. The hypernuclear sector of hadronic physics is not just a simple extension of zero-strangeness phenomena.