The Nucleon-Nucleon Interaction in a Chiral Effective Field Theory
The Nucleon-Nucleon Interaction in a Chiral Effective Field Theory
The Nucleon-Nucleon Interaction in a Chiral Effective Field Theory
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4.5. Results for the NNLO-ß approach 151<br />
already <strong>in</strong> the Bonn potential, namely that this particular partial wave is essential dom<strong>in</strong>ated by<br />
correlated TPE [213]. We also note that the description of 3 D1 and 3 D2 is worse <strong>in</strong> NNLO-ß than<br />
<strong>in</strong> NNLO. For the F -waves, the differences between the two approaches are very small, with the<br />
exception of 3 F4, which is improved <strong>in</strong> the presence of the isobar. <strong>The</strong> most significant effect <strong>in</strong><br />
the higher partial waves shows up <strong>in</strong> 3G5 as shown <strong>in</strong> fig. 4.17. Clearly, two-pion correlations not<br />
related to the ß play an important role to br<strong>in</strong>g the prediction for this partial wave <strong>in</strong> agreement<br />
with the data. <strong>The</strong> deuteron properties for an exponential regulator with A = 1.05 Ge V are listed<br />
<strong>in</strong> table 4.7. Most observables come out <strong>in</strong> between the NLO and NNLO results for the NNLO-ß<br />
approach. <strong>The</strong> sole exception is the quadrupole moment, which is improved.<br />
An important conclusion follow<strong>in</strong>g from comparison of the NNLO and NNLO-ß results is that<br />
simply us<strong>in</strong>g resonance saturation to encode the physics of the isobar <strong>in</strong> the dimension two pionnucleon<br />
LECs turns out to be a sufficient procedure <strong>in</strong> the two-nucleon sector. We also note that<br />
explicit isobar degrees of freedom were considered <strong>in</strong> ref. [78]. A direct comparison with their<br />
work is, however, not possible s<strong>in</strong>ce no separate result for fits with and without delta are given.