scholarly journals On the spin excitation energy of the nucleon in the Skyrme model

2016 ◽  
Vol 25 (11) ◽  
pp. 1650097 ◽  
Author(s):  
C. Adam ◽  
J. Sanchez-Guillen ◽  
A. Wereszczynski
Keyword(s):  
Excitation Energy ◽  
Skyrme Model ◽  
Binding Energies ◽  
Spin Excitation ◽  
Rigid Rotor ◽  
Delta Resonance ◽  
Relativistic System ◽  
Physical Constraints ◽  
The Masses ◽  
Large Spin

In the Skyrme model of nucleons and nuclei, the spin excitation energy of the nucleon is traditionally calculated by a fit of the rigid rotor quantization of spin/isospin of the fundamental Skyrmion (the hedgehog) to the masses of the nucleon and the Delta resonance. The resulting, quite large spin excitation energy of the nucleon of about [Formula: see text] is, however, rather difficult to reconcile with the small binding energies of physical nuclei, among other problems. Here, we argue that a more reliable interval of values for the spin excitation energy of the nucleon, compatible with many physical constraints is between [Formula: see text] and [Formula: see text]. The fit of the rigid rotor to the Delta, on the other hand, is problematic in any case, because it implies the use of a nonrelativistic method for a highly relativistic system.

Low-energy pion photoproduction from p-shell nuclei

1990 ◽  
Vol 68 (11) ◽  
pp. 1270-1278 ◽  
Author(s):  
C. Bennhold ◽  
L. Tiator ◽  
L. E. Wright
Keyword(s):  
Form Factors ◽  
Pion Photoproduction ◽  
Binding Energies ◽  
Wave Functions ◽  
Low Energy ◽  
Delta Resonance ◽  
Transverse Electromagnetic ◽  
Coulomb Effects ◽  
Correction Terms ◽  
Space Approach

Low-energy pion photoproduction off 6Li, 10B, and 14N has been reinvestigated in a DWIA framework that includes a number of improvements neglected in previous analyses. The production operator is based on Feynman diagrams and includes correction terms of order p2/M2 and higher. An s-channel delta resonance term is included with both longitudinal and transverse electromagnetic couplings. Rather than using on harmonic oscillator for the nucleon orbitals we employ Woods–Saxon wave functions that have been adjusted to fit electron-scattering form factors and single-particle binding energies. Furthermore, we include the Coulomb potential without approximation in our momentum-space approach. Using more realistic wave functions and including corrections to the production amplitude that have been neglected before leads to considerable improvement in the case of 10B and 14N when compared with existing data. The Coulomb effects are shown to change the cross section by about 30% close to threshold but are negligible at higher energies.

LEVEL DENSITIES IN LIGHTER NUCLEI

1965 ◽  
Vol 43 (7) ◽  
pp. 1248-1258 ◽  
Author(s):  
A. Gilbert ◽  
F. S. Chen ◽  
A. G. W. Cameron
Keyword(s):  
Excitation Energy ◽  
Ground State ◽  
Shell Structure ◽  
Mass Number ◽  
State Energy ◽  
Binding Energies ◽  
Light Nuclei ◽  
Cumulative Number ◽  
Additional Consideration ◽  
Level Densities

There has been discussion in the literature as to whether the cumulative number of levels in light nuclei varies more nearly as exp(const. [Formula: see text]) or exp(const. E), where E is the excitation energy. The question is examined in this paper. It is found that if one constructs "step diagrams" by plotting the cumulative number versus the energy, both formulas represent the data almost equally well. However, additional consideration of levels counted above neutron and proton binding energies shows that exp(const. [Formula: see text]) fails badly to represent the data, whereas exp(const. E) continues to give good fits. In either case E may be measured above an arbitrary ground-state energy E0. If the satisfactory formula is written in the form exp(E–E0)/T, then it is found that the dependence of the slope on mass number may be expressed in approximately the form T−1 = 0.0165A MeV−1, but there are significant deviations from this relation apparently related to shell structure. The intercepts E0 are quite variable but are roughly clustered according to the oddness or evenness of the neutron and proton numbers of the nucleus.

scholarly journals Pythagorean numbers and the calculation of the masses of the elementary particles

2021 ◽  
Vol 34 (3) ◽  
pp. 322-330
Author(s):  
Borros Arneth
Keyword(s):  
Elementary Particle ◽  
Fine Structure ◽  
Binding Energy ◽  
Structure Constant ◽  
Elementary Particles ◽  
Binding Energies ◽  
Fine Structure Constant ◽  
Internal Mass ◽  
Pythagorean Numbers ◽  
The Masses

We attempt here to calculate the particle masses for all known elementary particles starting from the Rydberg equation and from the Sommerfeld fine structure constant. Remarkably, this is possible. Next, we try to explain why this is possible and what the meaning of the approach seems to be. Thereby, we find some interesting connections. In addition, we realize that there are two different kinds of mass-charge binding energies in an elementary particle: The internal mass-charge binding energy and the external mass-charge binding energy. These two kinds of mass-charge binding energies can explain the higher masses of the highly charged brother particles in some of the heavier particle triplets (such as the charmed sigma particles).

Bogomol’nyi-Prasad-Sommerfield Skyrme Model and Nuclear Binding Energies

2013 ◽  
Vol 111 (23) ◽  
Author(s):  
C. Adam ◽  
C. Naya ◽  
J. Sanchez-Guillen ◽  
A. Wereszczynski
Keyword(s):  
Skyrme Model ◽  
Binding Energies ◽  
Nuclear Binding

scholarly journals Nuclear binding energies from a Bogomol'nyi-Prasad-Sommerfield Skyrme model

2013 ◽  
Vol 88 (5) ◽  
Author(s):  
C. Adam ◽  
C. Naya ◽  
J. Sanchez-Guillen ◽  
A. Wereszczynski
Keyword(s):  
Skyrme Model ◽  
Binding Energies ◽  
Nuclear Binding

SHORT RANGE RESONATING VALENCE BOND THEORIES AND SUPERCONDUCTIVITY

1990 ◽  
Vol 04 (03) ◽  
pp. 225-232 ◽  
Author(s):  
EDUARDO FRADKIN ◽  
STEVEN KIVELSON
Keyword(s):  
Quantum Electrodynamics ◽  
Short Range ◽  
Valence Bond ◽  
Spin Excitation ◽  
Spin Liquid ◽  
Low Density ◽  
Dimer Model ◽  
Weakly Coupled ◽  
Spin Liquid State ◽  
Large Spin

We consider the nature of superconductivity near a spin-liquid state with a large spin-excitation-gap. We argue that the quantum-dimer-model with holes is a good approximation in this limit. The insulator is shown to be exactly equivalent to compact quantum electrodynamics, and has a massive spectrum. The doped system is a superconductor with a low density phase characterized by tightly bound pairs and a high density phase with two weakly coupled condensates.

scholarly journals A study of shell model neutron states in 207,209Pb using the generalized Woods–Saxon plus spin-orbit potential

2016 ◽  
Vol 25 (08) ◽  
pp. 1650055 ◽  
Author(s):  
J. A. Liendo ◽  
E. Castro ◽  
R. Gómez ◽  
D. D. Caussyn
Keyword(s):  
Angular Momentum ◽  
Excitation Energy ◽  
Single Particle ◽  
Binding Energies ◽  
Nuclear Surface ◽  
Spin Orbit ◽  
Coupling Term ◽  
Angular Momentum Quantum Number ◽  
Orbit Potential ◽  
Number Formula

The experimental binding energies of single-particle and single-hole neutron states belonging to neutron shells that extend from [Formula: see text] = 126–184 and 82–126, respectively, have been reproduced by solving the Schrödinger equation with a potential that has two components: the generalized Woods–Saxon (GWS) potential and the spin-orbit (SO) coupling term. The GWS potential contains the traditional WS potential plus a term (SU) whose intensity reaches a maximum in the nuclear surface. Our results indicate the existence of an explicit relationship between the strength of the SU potential and the orbital angular momentum quantum number [Formula: see text] of the state. This dependence has been used to make reasonable predictions for the excitation energy centroids of states located inside and outside the neutron shells investigated. Comparisons are made with results reported in previous investigations.

Dynamics of a Self-Propelling Wheel With Three Eccentric Masses

2000 ◽  
Author(s):  
Tuhin K. Das ◽  
Ranjan Mukherjee
Keyword(s):  
Potential Energy ◽  
Constant Velocity ◽  
Simple Approach ◽  
Constant Acceleration ◽  
Physical Constraints ◽  
Straight Line ◽  
Radial Spokes ◽  
Simulation Results ◽  
The Masses ◽  
Variable Potential

Abstract This paper investigates the dynamics of a rolling disk with three unbalance masses that can slide along radial spokes equispaced in angular orientation. The objective is to design trajectories for the masses that satisfy physical constraints and enable the disk to accelerate or move with constant velocity. The disk is designed to remain vertically upright and is constrained to move along a straight line. We design trajectories for constant acceleration through detailed analysis using a dynamic model. The analysis considers two separate cases; one where the potential energy of the system is conserved, and the other where it continually varies. Whereas trajectories conserving potential energy are limacons, the variable potential energy trajectories are the most general and allow greater acceleration. Following the strategy for constant acceleration maneuvers, we give a simple approach to tracking an acceleration profile and provide simulation results.

scholarly journals Open string QED meson description of the X17 particle and dark matter

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Cheuk-Yin Wong
Keyword(s):  
Dark Matter ◽  
Gamma Rays ◽  
Open String ◽  
High Energy ◽  
Binding Energies ◽  
Meson State ◽  
Electron Positron ◽  
Energy States ◽  
Energy Hadron ◽  
The Masses

AbstractAs a quark and an antiquark cannot be isolated, the intrinsic motion of a composite $$ q\overline{q} $$ q q ¯ system in its lowest-energy states lies predominantly in 1+1 dimensions, as in an open string with the quark and the antiquark at its two ends. Accordingly, we study the lowest-energy states of an open string $$ q\overline{q} $$ q q ¯ system in QCD and QED in 1+1 dimensions. We show that π0, η, and η′ can be adequately described as open string $$ q\overline{q} $$ q q ¯ QCD mesons. By extrapolating into the $$ q\overline{q} $$ q q ¯ QED sector in which a quark and an antiquark interact with the QED interaction, we find an open string isoscalar I(Jπ) = 0(0−) QED meson state at 17.9±1.5 MeV and an isovector (I(Jπ) = 1(0−), I3 = 0) QED meson state at 36.4±3.8 MeV. The predicted masses of the isoscalar and isovector QED mesons are close to the masses of the hypothetical X17 and E38 particles observed recently, making them good candidates for these particles. The decay products of QED mesons may show up as excess e+e− and γγ pairs in the anomalous soft photon phenomenon associated with hadron productions in high-energy hadron-proton collisions and e+-e− annihilations. Measurements of the invariant masses of excess e+e− and γγ pairs will provide tests for the existence of the open string $$ q\overline{q} $$ q q ¯ QED mesons. An assembly of gravitating QED mesons are expected to emit electron-positron pairs and/or gamma rays and their decay energies and lifetimes will be modified by their gravitational binding energies. Consequently, a self-gravitating isoscalar QED meson assembly whose mass M and radius R satisfy (M/M⨀)/(R/R⨀) ≳ 2 4.71 × 105 will not produce electron-positron pairs nor gamma rays and may be a good candidate for the primordial dark matter.

Dynamic Analysis of Rectilinear Motion of a Self-Propelling Disk With Unbalance Masses

2000 ◽  
Vol 68 (1) ◽  
pp. 58-66 ◽  
Author(s):  
T. Das ◽  
R. Mukherjee
Keyword(s):  
Potential Energy ◽  
Dynamic Model ◽  
Center Of Mass ◽  
Static Model ◽  
Rectilinear Motion ◽  
Constant Acceleration ◽  
Physical Constraints ◽  
Straight Line ◽  
Radial Spokes ◽  
The Masses

This paper investigates the dynamics of a rolling disk with three unbalance masses that can slide along radial spokes equispaced in angular orientation. The objective is to design trajectories for the masses that satisfy physical constraints and enable the disk to accelerate or move with constant velocity. The disk is designed to remain vertically upright and is constrained to move along a straight line. We design trajectories for constant acceleration, first using a static model, and then through detailed analysis using a dynamic model. The analysis based on the dynamic model considers two separate cases; one where the potential energy of the system is conserved, and the other where it continually varies. Whereas trajectories conserving potential energy are quite similar to those obtained from the static model, the variable potential energy trajectories are the most general. A number of observations related to the system center-of-mass are made with respect to both trajectories. Following the strategy for constant acceleration maneuvers, we give a simple approach to tracking an acceleration profile and provide some simulation results.

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