Subthreshold resonances in few-neutron systems

Sofianos, S. A.; Rakityansky, S. A.; Vermaak, G. P.

doi:10.1088/0954-3899/23/11/010

Cited by 44 publications

(66 citation statements)

References 18 publications

(50 reference statements)

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“…From such large values for the scattering length a(ηN), Haider and Liu [10] have shown that η can be bound in nuclei with A ≥ 12. Other groups have also found similar results [12,13,14,15].…”

Section: Introductionsupporting

confidence: 70%

“…[44], [45], [14] bound states in light nuclei were calculated by the finite rank approximation (FRA). Within this approximation the motion of the η and of the nucleons inside the nucleus are treated separately.…”

Section: The η Nucleus Potential and Search For Quasi Bound Statesmentioning

confidence: 99%

“…It is interesting to have a closer look to the predictions for the very light nuclei. Sofianos and Rakityansky [14] calculated for a scattering length a ηN = (0.55+i0.30) fm, which is the scattering length extracted by Wilkin [30] from production data, the pole positions in the complex momentum plane, which are shown in Fig. 11.…”

Section: Positions and Widths Of η Bound Statesmentioning

confidence: 99%

“…13 also calculations for the nucleus 4 He are shown which were obtained within the framework of FRA [14] with scattering length a ηN = 0.2 + 0.1n + i0.3 fm with n=1-8. The results are shown counter clockwise.…”

Section: Relation Between Pole Parameters and Effective Range Parametersmentioning

confidence: 99%

See 3 more Smart Citations

Search for quasi boundηmesons

Machner

2015

J. Phys. G: Nucl. Part. Phys.

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The search for a quasi bound η meson in atomic nuclei is reviewed. This tentative state is studied theoretically as well as experimentally. The theory starts from elastic η nucleon scattering which is derived from production data within some models. From this interaction the η nucleus interaction is derived. Model calculations predict binding energies and widths of the quasi bound state. Another method is to derive the η nucleus interaction from excitation functions of η production experiments. The s wave interaction is extracted from such data via final state interaction theorem. We give the derivation of s wave amplitudes in partial wave expansion and in helicity amplitudes and their relation to observables. Different experiments extracting the final state interaction are discussed as are production experiments. So far only three experiments give evidence for the existence of the quasi bound state: a pion double charge exchange experiment, an effective mass measurement, and a transfer reaction at recoil free kinematics with observation of the decay of the state.

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Section: Introductionsupporting

confidence: 70%

Section: The η Nucleus Potential and Search For Quasi Bound Statesmentioning

confidence: 99%

Section: Positions and Widths Of η Bound Statesmentioning

confidence: 99%

Section: Relation Between Pole Parameters and Effective Range Parametersmentioning

confidence: 99%

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Search for quasi boundηmesons

Machner

2015

J. Phys. G: Nucl. Part. Phys.

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“…The only rigorous study of tetraneutron resonances was accomplished in ref. [10] using the simplistic MT I-III nn interaction, which contains only S -waves. Unfortunately no observable resonances have been found there and only the existence of some broad subthreshold structures (S-matrix poles with negative real energy parts) was pointed out.…”

Section: Introductionmentioning

confidence: 99%

Is a physically observable tetraneutron resonance compatible with realistic nuclear interactions?

Lazauskas

Carbonell

2005

Phys. Rev. C

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The possible existence of four-neutron resonances close to the physical energy region is explored. Faddeev-Yakubovsky equations have been solved in configuration space using realistic nucleonnucleon interaction models. Complex Scaling and Analytical Continuation in the Coupling constant methods were used to follow the resonance pole trajectories, which emerge out of artificially bound tetraneutron states. The final pole positions for four-neutron states lie in the third energy quadrant with negative real energy parts and should thus not be physically observable.

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Analyzing the contribution of individual resonance poles of the S‐matrix to two‐channel scattering

Rakityansky

Elander

2005

Int J of Quantum Chemistry

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ABSTRACT:A two-channel problem is considered within a method based on firstorder differential equations that are equivalent to the corresponding Schrödinger equation but more convenient for dealing with resonant phenomena. Using these equations, it is possible to calculate directly the Jost matrix for practically any complex value of the energy. The spectral points (bound and resonant states) can therefore be located in a rigorous way, namely, as zeros of the Jost matrix determinant. When calculating the Jost matrix, the differential equations are solved and thus, at the same time, the wave function is obtained with the correct asymptotic behavior analytically embedded in the solution. The method offers a very accurate way of calculating not only total widths of resonances but their partial widths as well. For each pole of the S-matrix, its residue can be calculated rather accurately, which makes it possible to obtain the Mittag-Leffler-type expansion of the Smatrix as a sum of the singular terms (representing the resonances) and the background term (contour integral). As an example, the two-channel model by Noro and Taylor is considered. It is demonstrated how the contributions of individual resonance poles to the scattering cross section can be analyzed using the Mittag-Leffler expansion and the Argand plot technique. This example shows that even poles situated far away from the physical real axis may make significant contributions to the cross section.

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Subthreshold resonances in few-neutron systems

Cited by 44 publications

References 18 publications

Search for quasi boundηmesons

Search for quasi boundηmesons

Is a physically observable tetraneutron resonance compatible with realistic nuclear interactions?

Analyzing the contribution of individual resonance poles of the S‐matrix to two‐channel scattering

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