 Subjects -> ASTRONOMY (Total: 94 journals)
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- Thermodynamics Properties of a Quantum Particle Confined into Two Elastic
Concentric Spheres-
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Abstract: Abstract We have investigated the quantum dynamics of a particle confined into two concentric spheres with radios fixed with a point-like defect in the mutual central point of the spheres, which can be seen as a vacancy or impurity. In this analyses we determine the energy spectrum of the system where we can observe that it is influenced by the topology of the elastic continuo medium due presence of the topological defect. Next, we have analyzed the quantum dynamics of a particle confined in a elastic spherical shell of radio fixed. In addition, we have determined the energy spectrum of a quantum particle subjected to a spherical hard-wall potential in this background. In all cases, we have determined the thermodynamics properties of the system which are influenced by the elastic medium topology.
PubDate: 2022-05-15
- Motion Around Out-of-Plane Equilibrium Points in the Frame of Restricted
Six-Body Problem Under Radiation Pressure-
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Abstract: Abstract The goal of the present manuscript is to study the existence of out-of-plane equilibrium points and their stability in the photogravitational restricted six-body problem. It is found that there exist two out-of-plane equilibria under the restrictions \(-\frac{4\mu }{1-4\mu }<q<0\) and \(0< \mu < 0.25\) , where q and \(\mu \) are the radiation factor and mass parameter, respectively. It is also observed that the out-of-plane equilibria are linearly unstable in the above mentioned interval. With the help of Poincaré section, we have examined the orbits such as consistent, periodic, quasi-periodic, disordered, or stochastic.
PubDate: 2022-05-13
- Two-Particle System with Harmonic Oscillator Potential in Non-commutative
Phase Space-
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Abstract: Abstract In this paper, we investigate the influence of non-commutativity of both coordinates and momenta on the motion of a two-particle system in the presence of harmonic oscillator potential in plane. We obtain the equations of motion for the center of mass and the reduced mass and show that how they are dependent to the non-commutative parameters. We also show that the non-commutativity can be interpreted as an external force to system. In the limit of commutative phase space ( \(\theta \rightarrow 0,\eta \rightarrow 0)\) , the results are also agreement with the results of ordinary phase space.
PubDate: 2022-05-07
- The Current Status of Electron Ion Collider in China
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Abstract: Abstract Measuring the internal structures of the nucleon and the nuclear matter is one of the hot scientific topics in the filed of high-energy nuclear physics, which can answer the fundamental questions about the emergent properties of the nucleon and the nuclear force that binds the nucleons together forming an atomic nucleus. The high-energy lepton-proton/nucleus scattering is a well-established and clear way to probe the inner structure of these subatomic particles, which attracts a lot of interests from the nuclear physicists worldwide. To pursue such scientific goals, an Electron-ion collider in China (EicC) has been proposed as a future high-energy nuclear physics project in China. EicC will focus on the sea quarks in the nucleon, which well compliments the projects of electron-ion collider in US and JLab 12 GeV upgrade. In this article, the plans and conceptual designs of the accelerator and the detectors of EicC are briefly discussed. We illustrate some highlights of the experiments that will be performed at EicC.
PubDate: 2022-05-04
- Celebrating 30 Years of Steven Weinberg’s Paper Nuclear Forces from
Chiral Lagrangians - an Introduction to the Special Issue-
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PubDate: 2022-05-03
- Preface: Yamada Conference LXXII: The 8th Asia-Pacific Conference on
Few-Body Problems in Physics (APFB2020)-
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PubDate: 2022-05-03
- Symmetries of the Nucleon–Nucleon S-Matrix and Effective Field
Theory Expansions-
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Abstract: Abstract The s-wave nucleon–nucleon scattering matrix (S-matrix) exhibits UV/IR symmetries which are hidden in the effective field theory (EFT) action and scattering amplitudes, and which explain some generic features of the phase shifts. These symmetries offer clarifying interpretations of existing pionless EFT expansions, and suggest starting points for novel expansions. The leading-order (LO) S-matrix obtained in the pionless EFT with scattering lengths treated exactly is shown to have a UV/IR symmetry which leaves the sum of s-wave phase shifts invariant. A new scheme, which treats effective range corrections exactly, and which possesses a distinct UV/IR symmetry at LO, is developed up to NLO (next-to-LO) and compared with data.
PubDate: 2022-04-30
- What Can Possibly Go Wrong'
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Abstract: Abstract A lot.
PubDate: 2022-04-29
- Progress of Underground Nuclear Astrophysics Experiment JUNA in China
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Abstract: Abstract Underground Nuclear Astrophysics Experiment in China (JUNA) takes the advantage of the ultra-low background in Jinping underground lab. High current mA level 400 KV accelerator with an ECR source, BGO and neutron detectors were commissioned. JUNA studies directly a number of nuclear reactions important to hydrostatic stellar evolution at their relevant stellar energies. In the first quarter of 2021, JUNA performed the direct measurements of \({}^{25}\mathrm{Mg}(\mathrm{p},\gamma ){}^{26}\mathrm{Al}, {}^{19}\mathrm{F}(\mathrm{p}, \alpha ){}^{16}\mathrm{O}, {}^{13}\mathrm{C}(\alpha ,\mathrm{n}){}^{16}\mathrm{O}\) and \(^{12}\) C( \(\alpha ,\gamma \) ) \(^{16}\) O near the Gamow window. The experimental results reflect the potential of JUNA with higher statistics, precision and sensitivity of the data. The preliminary results of JUNA experiment and future plan are given.
PubDate: 2022-04-13
- Emergent Hadron Mass in Strong Dynamics
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Abstract: Abstract Emergent Hadron Mass (EHM) is a mechanism capable of explaining both the unnaturally small (pion) and large (proton) masses of hadrons and if not the origin of confinement, then intimately connected with it. Even though the modern formulation of EHM has only recently been completed, it is rapidly becoming a fundamental focus for modern and future experimental efforts aimed at understanding the strong force within the Standard Model. Using Dyson–Schwinger equations for the gluon, ghost and quark propagators, I will introduce the main EHM concepts and illustrate how far this framework can take us in understanding strong interaction phenomenology.
PubDate: 2022-04-12
- Effect of Earth’s Equatorial Ellipticity on the Resonant Curve and Phase
Portrait of Geo-centric Satellite Under the Gravitational Effect of the
Earth–Moon–Sun System by Using Unperturbed Solution-
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Abstract: Abstract In this article, we investigated the resonant curves of geo-centric satellite due to the rate of change in earth’s equatorial ellipticity parameter \((\dot{\gamma })\) , moon’s angular velocity around the earth \((\dot{\vartheta })\) , and angular velocity of bary-center \((\dot{\Theta })\) around the sun. We expressed the equations of the motion of the satellite in a spherical coordinate system using the earth’s potential. The system of equations are reduced into a second-order ordinary differential equation and determined its solution. From the solution, it is noted that resonance appears due to the frequencies \(\dot{\delta _{s0 }}\) , \(\dot{\gamma }\) , \(\dot{\Theta _0}\) and \(\dot{\vartheta _0}\) at ten resonant points \({\dot{\delta }_{s0}}={2\dot{\gamma }}\) , \({\dot{\delta }_{s0}}={\dot{\gamma }}\) , \({\dot{\delta }_{s0}}={2\dot{\Theta }_0}\) , \({\dot{\delta }_{s0}}={\dot{\Theta }_0}\) , \({\dot{\delta }_{s0}}=\frac{{2 \dot{\Theta }_0}}{3}\) , \({\dot{\delta }_{s0}}=\frac{\dot{\Theta }_0}{2}\) , \({\dot{\delta }_{s0}={2\dot{\vartheta _0}}}\) , \({\dot{\delta }_{s0}={\dot{\vartheta _0}}}\) , \({\dot{\delta }_{s0}=\frac{{2\dot{\vartheta _0}}}{3}}\) , and \({\dot{\delta }_{s0}=\frac{{dot{\vartheta _0}}}{2}}\) , where \({\dot{\delta }_{s0}}\) , \({\dot{\Theta }_0}\) and \({\dot{\vartheta _0}}\) are the steady-state value of \({\dot{\delta }_{s}}\) , \({\dot{\Theta }}\) and \({\dot{\vartheta }}\) respectively. We have drawn the resonant curves corresponding to the resonant points. From the graph, it is observed that the effect of earth’s equatorial ellipticity parameter on the resonant curves are very small. Also, we have shown the effect of eccentricity (e) and semi-major axes (a) on the oscillatory amplitudes \((A_i)\) , where \(i=1,2,3\ldots 21\) . Finally, we have analyzed the phase portrait by using Poincaré section method when the system is free from forces.
PubDate: 2022-04-04
- Improvement of the Envelope Theory for Systems with Different Particles
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Abstract: Abstract The envelope theory is a method to compute approximate eigensolutions of quantum N-body Hamiltonians with a quite general structure in D dimensions. The advantages of the method are that it is easy to implement and that N is treated as any other parameters of the Hamiltonian, allowing the computation for systems of all sizes. If solutions are reliable, they are generally not very accurate. In the case of systems with identical particles for \(D \ge 2\) , it is possible to improve the precision of the eigenvalues by combining the envelope theory with a generalisation to N-body of the dominantly orbital state method. It is shown that a similar improvement can be achieved in the case of systems composed of identical particles plus a different one. The quality of the new procedure is tested with different systems.
PubDate: 2022-03-30
- Connecting the Dirac Equation in Flat and Curved Spacetimes via Unitary
Transformation-
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Abstract: Abstract In this work, the extension of the symmetrically spherical Dirac equation in the context of supersymmetric quantum mechanics in curved spacetime is investigated in presence of vector and tensor potentials given by V(r) and A(r), respectively, with the line element given by \(ds^2 = (1+\alpha ^2 U(r))^2(dt^2-dr^2) - r^2d\theta ^2 - r^2\sin ^2\theta d\phi ^2\) , where U(r) is a scalar potential and \(\alpha \) is fine structure constant. Through a unitary transformation given by \(U^{'}(\eta ) = \exp (i\alpha \eta \sigma ^2/2)\) we decouple the radial wave functions and obtain an equation analogous to Schrödinger equation in the context of supersymmetric quantum mechanics when \( U(r) = -\epsilon V(r) \) , so we can write the potential V(r) , U(r) and A(r) in terms of the superpotential W(r) . With this, the class of shape-invariant potentials can be exact solved in curved spacetime with the coupling considered. For the particular case \( \eta = 0 \) , we recover the problem in flat spacetime, so the unitary operator \( U^{'}(\eta ) \) connects the systems with shape-invariant potentials in flat and curved spacetimes. As applications, two systems were analyzed: the harmonic oscillator and the Coulomb potential.
PubDate: 2022-03-26
- Lorentz Symmetry Breaking Effects Around a Cylindrical Cavity
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Abstract: Abstract From a model that goes beyond the Standard Model, we study Lorentz symmetry breaking effects around a cylindrical cavity at a low-energy regime. We consider a background of the Lorentz symmetry violation determined by a fixed vector field, then, we study the influence of a cut-off point on a harmonic potential induced by the effects of the Lorentz symmetry violation. We show that the cut-off point modifies the spectrum of energy of the harmonic-type potential. One aspect observed is the infinity degeneracy of the energy levels. Besides, we discuss a lower bound for the Lorentz symmetry violation parameters.
PubDate: 2022-03-25
- One-Neutron Removal Cross Sections for $$^{16}$$ 16 N Isomeric State
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Abstract: Abstract It is well known that the enhancement of halo neutron removal cross sections in neutron halo nuclei. This is one of the evidence for the neutron halo structure. Because the valence neutron of the isomeric state in \(^{16}\) N is considered to be mainly occupying in the s-orbital, we studied the nuclear structure of \(^{16}\) N as a candidate for neutron halo nucleus. In this study, we measured one-neutron removal cross sections \(\sigma _{-1n}\) using secondary beams of \(^{16}\) N with a mixture of ground and isomeric states. We used two types of primary beams, \(^{15}\) N and \(^{18}\) O, to produce \(^{16}\) N beams with different isomeric ratios (8.7, 24.2a \(^{16}\) N beam with a large isomeric ratio is large compared to that obtained with another beam with a small isomeric state. This result suggests that the \(^{16}\) N isomeric state is considered to have a neutron-halo-like structure.
PubDate: 2022-03-21
- Structure of $$\pmb K\pmb K\pmb K^{\pmb {bar}}$$ K K K bar – $$K{\pmb
{\pi }}{\pmb {\pi }}$$ K π π – $$K{\pmb {\pi }}{\pmb {\eta }}$$ K π
η Three-Body Resonance and Partial Decay Widths of $${\pmb K}(\pmb
{1460})$$ K ( 1460 )-
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Abstract: Abstract Using the complex-scaling method, we discuss the coupled-channel \(KKK^{bar}\) – \(K\pi \pi \) – \(K\pi \eta \) three-body resonance and determine the resonance pole with KK, \(KK^{bar}\) – \(\pi \pi \) , \(KK^{bar}\) – \(\pi \eta \) and \(K\pi \) two-body potentials describing two-body scattering properties and \(f^0\) and \(a^0\) resonances. It is shown that the three-body resonance can be interpreted as K(1460). To estimate the partial decay widths of this three-body resonance, we calculate the partial-wave components in the resonance wave function and evaluate roughly the partial decay widths in \(K^*\pi \) , \(\varepsilon K\) and \(\rho K\) modes. We find that additional p-wave components are needed to explain the experimental partial decay widths of K(1460).
PubDate: 2022-03-19
- Residual Cut-Off Dependence and Power Counting: The Deuteron as a Case
Study-
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Abstract: Abstract Effective field theories (EFTs) require regularization and renormalization to gain predictive power. While regularization is inconsequential from the point of view of the observable predictions of EFT—in a renormalized theory predictions are regulator-independent once the cutoff is removed—the particular details of regulator dependence might provide interesting insights into the inner workings of an EFT. In fact, the analysis of regulator dependence has been frequently suggested as a tool to study the ordering scheme or power counting of EFTs. We show here the quantitative differences betweeen inferred residual cutoff dependence from different regulators, thereby showing that cutoff variations might provide limited information about uncertainties and power counting (at least in practical settings).
PubDate: 2022-03-15
- Study on the $${\pmb {2}}^{\pmb +}_{\pmb 2}$$ 2 2 + Resonance in $$^{\pmb
6}$$ 6 He via Analysis of $$^{\pmb 6}$$ 6 He( $${\pmb p}$$ p , $${\pmb
p'}$$ p ′ ) Reactions-
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Abstract: Abstract \(^6\) He is known as two-neutron halo nuclei and has a Borromean structure in which there is no bound state in the binary subsystems. To explore resonances of unstable nuclei, the (p, \(p'\) ) reaction with the inverse kinematics has been often used. The \(2^{+}_{2}\) state has been investigated via various structural calculations and experimental studies. Unfortunately, the contribution of this state in the energy spectrum does not show a shape structure. Thus, the resonant energy and decay width of the \(2^{+}_{2}\) state have never been clear. To clarify the properties, it is required an accurate analysis of treating not only resonant contributions but also nonresonant contributions in energy spectra. In this study, we investigated the \(2^{+}_{2}\) resonant state via the analysis of \(^6\) He(p, \(p'\) ) reaction by using the continuum-discretized coupled-channels method. To describe the resonant and nonresonant state components, we also applied the complex scaling method to the analysis.
PubDate: 2022-03-15
- Electromagnetic Transitions in the Spectrum of a Confined Hydrogen Atom
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Abstract: Abstract Transition probabilities per time unit in the spectrum of the hydrogen atom confined in a spherical cavity are studied with the Dirac equation. The calculations are performed with simple and accurate expansions of the Dirac components provided by the Lagrange-mesh method with small numbers of scaled Jacobi mesh points. The initial and final states as well as intermediate states occurring in two-photon transitions are described with a single Lagrange mesh. With this simplification, accurate matrix elements are easily computed with the Gauss quadrature associated with the Lagrange–Jacobi mesh. One-photon transitions are considered from the \(n = 2\) and 3 levels. Most transition probabilities increase as a negative power of the confinement radius when it becomes small. The two-photon \(2s_{1/2}-1s_{1/2}\) transition stops being the main deexcitation channel of the \(2s_{1/2}\) level when the confinement radius decreases below about 15 atomic units. The \(2p_{1/2}\) and \(2p_{3/2}\) levels come below the \(2s_{1/2}\) level and allow a faster one-photon deexcitation.
PubDate: 2022-03-14
- Masses, Radii and Regge Trajectories of $$\Sigma _{u}^{-}$$ Σ u -
State Hybrid Charmonium-
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Abstract: Abstract In this paper, masses, radii and \(E_1\) radiative transitions of \(\Sigma ^-_u\) state hybrid charmonium mesons for radial and orbital excitations are calculated by numerically solving the Schrödinger equation with non-relativistic potential model. Results for calculated masses of \(\Sigma ^-_{u}\) states charmonium hybrid mesons are found to be close to the results obtained through lattice simulations. Calculated masses are used to construct Regge trajectories. It is found that the trajectories are almost linear and parallel.
PubDate: 2022-03-13
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