Hyperon–nucleon interaction within chiral effective field theory revisited
J. Haidenbauer, U.-G. Meißner, A. Nogga
Abstract
Abstract The $$\varLambda N$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Λ</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math> and $$\varSigma N$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Σ</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math> interactions are considered at next-to-leading order in SU(3) chiral effective field theory. Different options for the low-energy constants that determine the strength of the contact interactions are explored. Two variants are analysed in detail which yield equivalent results for $$\varLambda N$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Λ</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math> and $$\varSigma N$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Σ</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math> scattering observables but differ in the strength of the $$\varLambda N \rightarrow \varSigma N$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Λ</mml:mi><mml:mi>N</mml:mi><mml:mo>→</mml:mo><mml:mi>Σ</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math> transition potential. The influence of this difference on predictions for light hypernuclei and on the properties of the $$\varLambda $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Λ</mml:mi></mml:math> and $$\varSigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Σ</mml:mi></mml:math> hyperons in nuclear matter is investigated and discussed. The effect of the variation in the potential strength of the $$\varLambda N$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Λ</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math> - $$\varSigma N$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Σ</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math> coupling (also called $$\varLambda -\varSigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Λ</mml:mi><mml:mo>-</mml:mo><mml:mi>Σ</mml:mi></mml:mrow></mml:math> conversion) is found to be moderate for the considered $$^3_\varLambda {{\mathrm{H}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mrow/><mml:mi>Λ</mml:mi><mml:mn>3</mml:mn></mml:msubsup><mml:mi>H</mml:mi></mml:mrow></mml:math> and $$^4_\varLambda \mathrm{He}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mrow/><mml:mi>Λ</mml:mi><mml:mn>4</mml:mn></mml:msubsup><mml:mi>He</mml:mi></mml:mrow></mml:math> hypernuclei but sizable in case of the matter properties. Further, the size of three-body forces and their relation to different approaches to hypernuclear interactions is discussed.