Abstract
The ΛN → NN interaction, the main responsible for the decay of heavy hypernuclei, is described within the effective field theory (EFT) framework. The EFT is developed up to (q⃗2), where q⃗ is the transferred momentum between the interacting baryons. Numerical values for the leading order low-energy constants are obtained by two means. First, from a fit to the hypernuclear decay observables, and second, by comparing the EFT to the one-meson-exchange model describing the same interaction. All the two-pion exchange diagrams entering at the next-to-leading in the EFT have been calculated.
Highlights
Being the lightest among the strange baryons, the ⇤ particle plays an essential role in the study of nuclear physics phenomena involving strangeness
Given an initial and a final state in the isospin basis, one can calcualte the matrix elements for the di↵erent operators defined in the previous sections
Using the same notation that is described in section 3.4.1 we write a general expression for the three caramel diagrams that depends on the label ↵ = a, b, c, which corresponds, respectively, to the masses and vertices of Figs
Summary
La teoria efectiva a ordre zeroes facilment derivable tenint en compte totes les possibles estructures de moment, spin i isospın que son compatibles amb les simetries del nostre problema, i te, a aquest ordre, nomes dues estructures operacionals i per tant dues constants de baixa energia. Primer s’han escrit totes les interaccions de contacte fins a aquest ordre, i despres, hem calculat tots els diagrames que participen en l’intercanvi de dos pions. Tanmateix, que la descripcio a ordre O(q2) inclou 15 constants de baixa energia (dues de les quals ja estan presents a ordre zero), i que par tant, donat el nombre de dades experimentals (independents) disponibles, fixar la interaccio a aquest ordrees quelcom no assumible en el futur immediat. Per tal d’obtenir un coneixement mes complet del problema hem comparat les interaccions de contacte que van acompanyades de les constants de baixa energia amb els potencials corresponents a l’intercanvi d’un meso pesat.
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