Chiral symmetry and the Higgs-boson<i>–</i>nucleon coupling

Abstract

The chiral-symmetry-breaking \ensuremath{\sigma} term as extracted from the pion-nucleon phase-shift and dispersion analysis implies that the Higgs boson coupling to the nucleon is dominated by the strange quarks. For ${\ensuremath{\sigma}}_{\ensuremath{\pi}N}$\ensuremath{\simeq}60 MeV the strange-quark contribution is an order of magnitude larger than that of any other flavor. This significantly increases the Higgs-boson--nucleon coupling from its chiral-symmetric value. Some of the phenomenological consequences are briefly discussed. In particular I reanalyze the low-energy nuclear and atomic experimental evidence against the existence of a light scalar boson, and compare the bounds to those originally derived with the expectation that the nucleon consists mainly of the up and down quarks. A summary review of the various issues concerning a large \ensuremath{\pi}N \ensuremath{\sigma} term is also provided.