scholarly journals Searches for the Σ-nucleus Potential

2020 ◽  
Vol 13 ◽  
pp. 191
Author(s):  
Th. Petridou
Keyword(s):  
Optical Potential ◽  
Plane Waves ◽  
Delta Function ◽  
Spin Orbit ◽  
Repulsive Potential ◽  
Green Function Method ◽  
Square Well ◽  
The Green Function ◽  
Hypernuclear Physics

The determination of the Σ-nucleus potential is the main orientation of the late Σ-hypernuclear physics. For this purpose, the last (Κ-,π+) light Σ-hypernuclear spectra were studied together with the recent (π-, Κ+)28Si_Σ spectrum in the context of the Green function method with a square well optical potential and a delta function spin-orbit interaction using plane waves. It was found that these spectra with a broad enhancement mainly at large energies are well described by a repulsive potential with nonzero imaginary and spin-orbit parts.

scholarly journals A simplified response function formalism for medium-heavy Λ hypernuclei

2019 ◽  
Vol 11 ◽  
Author(s):  
Theodora Petridou
Keyword(s):  
Response Function ◽  
Optical Potential ◽  
Plane Waves ◽  
Bound State ◽  
Green Function Method ◽  
Neutron Hole ◽  
Proposed Model ◽  
Square Well ◽  
The Green Function ◽  
Experimental Values

There is a variety of spectra for Λ hypernuclei (from light to heavy) which contain many peaks ranging from the deepest orbits to the surface ones. An approach is presented for the calculation of the bound state specrum of Λ hypernuclei, where the cross section is expressed through the response function. This was achieved in the framework of the Green function method with a square well optical potential using the plane waves. An analytic treatment was made for the prominent peaks with the contribution of only the valence neutron-hole series and a Gaussian folding was obtained for the rest spectrum. The method was applied mainly to the (π+,Κ+) medium to heavy Λ hypernuclei and also to the (Ä"~in-flight, π~) Λ hypernuclear spectra (with respect to their differences). The results are satisfactory compared to the experimental values. The main advantage of the proposed model is its simplicity. Possible extensions and improvements of this method are also suggested.

scholarly journals A study on the (π- , K+) reaction production of Σ-hypernuclei

2019 ◽  
Vol 14 ◽  
pp. 185
Author(s):  
Theodora Petridou
Keyword(s):  
Green Function ◽  
Energy Range ◽  
Function Method ◽  
Simplified Model ◽  
Wide Energy Range ◽  
Spin Orbit ◽  
Repulsive Potential ◽  
Green Function Method ◽  
Wide Energy ◽  
The Green Function

The ( π - , K+) reaction production was used recently to produce medium to heavy Σ-hypernuclei with good statistics. The observed spectra do not contain peaks and have a wide energy range. These spectra were studied within the Green function method with a simplified model. The investigation showed that a strong repulsive potential with medium imaginary and spin-orbit parts describes well the spectra.

The density of states in dilute solid solutions

1966 ◽  
Vol 292 (1430) ◽  
pp. 433-440 ◽  
Keyword(s):  
Green Function ◽  
Density Of States ◽  
Solid Solutions ◽  
Level Shift ◽  
Green Function Method ◽  
Pure Solvent ◽  
Energy Level Shift ◽  
The Difference ◽  
The Green Function

The difference in the density of states in energy in a dilute solid solution, relative to its value in the pure solvent, is derived. It is shown to be simply related to the energy level shift induced by virtual electron scattering off the solute ions and to the density of states in the pure solvent. The result, which follows from a brief physical argument, is shown to be completely equivalent to that obtained from a far more laborious derivation by means of Green function techniques. An application to the determination of the specific heat of dilute metallic solid solutions is given and a former incomplete result, as derived by Jones from an approximate evaluation of the Green function method, is amended.

scholarly journals The (K-, π+)Σ- - hypernuclear production in flight

2019 ◽  
Vol 3 ◽  
pp. 63
Author(s):  
Th. Petridou ◽  
C. Daskaloyannis
Keyword(s):  
Experimental Data ◽  
Interaction Model ◽  
Delta Function ◽  
Spin Orbit ◽  
Central Potential ◽  
Flight Data ◽  
Potential Depth ◽  
Square Well ◽  
Theoretical Results ◽  
Simple Interaction

The in-flight (K-,π+) Σ~-hypernuclear spectra are studied, using a simple interaction model with a square well central part and a delta function spin-orbit Σ-nuclearcore interaction. A comparison is made between the theoretical results and the in-flight (Α'~,π+) experimental data for 12Σ C, 16Σ Ο and 6Σ Li. A shallow potential, with a central potential depth of Vc = (-5 - il5)MeV and a spin-orbit depth of Vao = lbMeV, gives a satisfactory representation of the CERN and BNL in-flight data.

The Green function method for the two-surface problem

1970 ◽  
Vol 8 (13) ◽  
pp. 1069-1071 ◽  
Author(s):  
F. Flores ◽  
F. Garcia-Moliner ◽  
J. Rubio
Keyword(s):  
Green Function ◽  
Function Method ◽  
Green Function Method ◽  
The Green Function
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