Today’s view on strangeness

Abstract

There are several different experimental indications, such as the pion-nucleon Σ term and polarized deep-inelastic scattering, which suggest that the nucleon wave function contains a hidden ss component. This is expected in chiral soliton models, which also predicted the existence of new exotic baryons that may recently have been observed. Another hint of hidden strangeness in the nucleon is provided by copious φ production in various NN annihilation channels, which may be due to evasions of the Okubo-Zweig-Iizuka rule. One way to probe the possible polarization of hidden ss pairs in the nucleon may be via Λ polarization in deep-inelastic scattering.

ΛΛinteractions in finite-density QCD sum rules

“…In this work, the πN sigma term in the new determinations (i.e., σ πN = 56 MeV) are adopted, and hence a large strange content of the nucleon (i.e., y = 0.5) are obtained according to the overviews in [24]. The reasonable results predicted by us support these new determinations.…”

“…where σ 0 πN is the πN sigma term in the limit of the vanishing strangeness, its value is in the range of σ 0 πN = 36 ± 7 MeV [23]. The recent determinations of the πN sigma term suggest larger values for it, i.e., σ πN = 64±8, (79 ± 7) MeV, hence y ∼ 0.5 [24,25,26]. Thus, in this work, we adopt the new determination of the strangeness content y ∼ 0.5, and constrain our discussions in the new determined region of σ πN , i.e., σ πN = 56 ∼ 86 MeV.…”

Sigma Terms and Strangeness Contents of Baryon Octet in Modified Chiral Perturbation Theory

“…[13]. When calculating to order 3, we consider only (2) MM . The problem with the expression provided in Refs.…”

“…The strangeness content of nucleon might not equal 0, for even vacuum has a nonzero strangeness quark condensate. [2] But a large y N is not acceptable in view of quark model, which does not exactly hold though, it has successfully explained many hadronic phenomena. The purpose of this work is to discuss sigma terms and strangeness contents of baryon octet in a modified chiral perturbation theory.…”

Matrix elements and baryon spectroscopy from unquenched lattice QCD with improved staggered quarks.

“…Group y Group n f y Borasoy and Meißner [14] 0.21 ± 0.20 Kentucky [15] 0 0.36(3) Borasoy [16] 0.20 ± 0.12 SESAM [17] 2 0.59(13) John Ellis [18] ∼ 0.6 UKQCD [19] 2 −0.28(33) of dark matter. It is convenient to discuss the ratios of matrix elements…”