Using chiral perturbation theory to extract the neutron-neutron scattering length from pi- d -> n n gamma
| dc.creator | Gardestig, A. | |
| dc.creator | Phillips, D. R. | |
| dc.date | 2005-01-20 | |
| dc.date | 2005-12-08 | |
| dc.date.accessioned | 2026-07-07T13:05:14Z | |
| dc.date.available | 2026-07-07T13:05:14Z | |
| dc.description | The reaction pi- d -> n n gamma is calculated in chiral perturbation theory so as to facilitate an extraction of the neutron-neutron scattering length (a_nn). We include all diagrams up to O(Q^3). This includes loop effects in the elementary pi- p -> gamma n amplitude and two-body diagrams, both of which were ignored in previous calculations. We find that the chiral expansion for the ratio of the quasi-free (QF) to final-state-interaction (FSI) peaks in the final-state neutron spectrum converges well. Our third-order calculation of the full spectrum is already accurate to better than 5%. Extracting a_nn from the shape of the entire pi- d -> n n gamma spectrum using our calculation in its present stage would thus be possible at the +-0.8 fm level. A fit to the FSI peak only would allow an extraction of a_nn with a theoretical uncertainty of +-0.2 fm. The effects that contribute to these error bars are investigated. The uncertainty in the $nn$ rescattering wave function dominates. This suggests that the quoted theoretical error of +-0.3 fm for the most recent pi- d -> n n gamma measurement may be optimistic. The possibility of constraining the nn rescattering wave function used in our calculation more tightly--and thus reducing the error--is briefly discussed. | |
| dc.description | 35 pages, 14 eps figures, references and figure added, discussions of errors extended and clarified, improved conclusions, typos corrected, to be published in PRC | |
| dc.identifier | https://arxiv.org/abs/nucl-th/0501049 | |
| dc.identifier | http://arxiv.org/abs/nucl-th/0501049 | |
| dc.identifier | Phys.Rev.C73:014002,2006 | |
| dc.identifier | doi:10.1103/PhysRevC.73.014002 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/227424 | |
| dc.subject | Nuclear Theory | |
| dc.subject | Nuclear Experiment | |
| dc.title | Using chiral perturbation theory to extract the neutron-neutron scattering length from pi- d -> n n gamma | |
| dc.type | text |