2021 Vol. 45, No. 8
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This analysis evaluates the possibility of the search for Dark Matter (DM) particles using events with a Z
In this study, we utilize a potentially versatile Bayesian parameter approach to compute the value of the pion charge radius and quantify its uncertainty from several experimental
A perturbative method of computing the total travel time of both null and lightlike rays in arbitrary static spherically symmetric spacetimes in the weak field limit is proposed. The resultant total time takes a quasi-series form of the impact parameter. The coefficient of this series at a certain order n is shown to be determined by the asymptotic expansion of the metric functions to the order
This paper presents the impact of the lepton transverse momentum
Excited states in the odd-A nucleus 71Ga have been studied via the 70Zn(7Li,
A multi-nucleon transfer and cluster decay experiment,
The isoscaling parameters
A systematic analysis on experimental data of the half-lives of nuclear double-
The isospin effects of projectile fragmentation at intermediate energies are investigated using an isospin-dependent Boltzmann-Langevin model. The collisions of mass-symmetric reactions including 58Fe, 58Ni + 58Fe, and 58Ni at intermediate energies, in the 30 to 100 MeV/A range, are studied for different symmetry energies. Yield ratios of the isotopic, isobaric, and isotonic pairs of fragments from the intermediate-mass region using three symmetry energies are extracted as functions of the N/Z ratio of the composite systems in the entrance channel and the incident energies. It is found that the yield ratios are sensitive to symmetry energies, especially for neutron-rich systems, and the calculations using soft symmetry energy are closer to the experimental data. The isospin effect is stronger for the soft symmetry energy, owing to the competition of the repulsive Coulomb force and the symmetry energy attractive force on the proton. For the first time, the splits are presented, revealing a transition from the isospin equilibrium at lower energies to translucency at intermediate energies. The results show a degree of transparency in that intermediate mass fragments undergo a transition from dependence on the composite systems in the entrance channel to reliance on the projectile and target nuclei.
A rovibrational model, including anharmonic, centrifugal, and Coriolis corrections, is used to calculate π, K, N, and Ʃ orbital and radial resonances. The four orbital excitations of the π meson correspond to the b(1235), π2(1670), b3(2030), and π4(2250) resonances. Its first four radial excitations correspond to the π(1300), π(1800), π(2070), and π(2360) resonances. The orbital excitations of the K meson are interpreted as the K1(1270), K2(1770), K3(2320), and K4(2500) resonances; its radial excitations correspond to the K(1460) and K(1830) resonances. The N orbital excitations are identified with the N(1520), N(1680), N(2190), N(2220), and N(2600) resonances. The first four radial excitations of the N family correspond to the N(1440), N(1880), N(2100), and N(2300) resonances. The orbital excitations of the Ʃ baryon are associated with the Ʃ(1670), Ʃ(1915), Ʃ(2100), and Ʃ(2250) resonances, whereas its radial excitations are identified with the Ʃ(1660), Ʃ(1770), and Ʃ(1880) resonances. The proposed rovibrational model calculations show a good agreement with the corresponding experimental values and allow for the prediction of hadron resonances, thereby proving to be useful for the interpretation of excited hadron spectra.
We present a preliminary study of charge exchange heavy ion induced reactions based on the constrained molecular dynamics (CoMD) model. The purpose is to test the capability of the model in predicting the occurrence of single charge exchange (SCE) and double charge exchange (DCE) exit channels for three different entrance channels at the same laboratory incident energy. The nuclear reaction dynamics and nuclear interaction within the CoMD approach are the only ingredients that have given, at this stage, promising results for SCE and DCE cross section calculations. The obtained results suggest an upgrade and possible future employment of the model for studies relating to the production of exotic nuclei through charge exchange reactions or DCE reactions and their connection with neutrinoless double beta decay.
A scheme to solve the Hamiltonian in the interacting boson-fermion model in terms of the SU(3) coupling basis is introduced, through which the effects of an odd particle on shape phase transitions (SPTs) in odd-A nuclei are examined by comparing the critical behaviors of some selected quantities in odd-even and even-even systems. The results indicate that the spherical to prolate (U(5)-SU(3)) SPT and spherical to
The dynamics of high-energy proton-induced spallation reactions on target nuclides of 56Fe, 58Ni, 107Ag, 112Cd, 184W, 181Ta, 197Au, and 208Pb are investigated with the quantum molecular dynamics transport model motivated by the China initiative Accelerator Driven System (CiADS) in Huizhou and the China Spallation Neutron Source (CSNS) in Dongguan. The production mechanism of light nuclides and fission fragments is thoroughly analyzed, and the results obtained thereby are compared with available experimental data. The statistical code GEMINI is employed in conjunction with a transport model for describing the decay of primary fragments. For the treatment of cluster emission during the preequilibrium stage, a surface coalescence model is implemented into the model. It is found that the available data in terms of total fragment yields are well reproduced in the combined approach for spallation reactions both on the heavy and light targets. The energetic light nuclides (deuteron, triton, helium isotopes etc) mainly created during the preequilibrium stage are treated within the framework of surface coalescence, whereas their evaporation is described in the conventional manner by the GEMINI code. With this combined approach, a good overall description of light clusters and neutron emission is obtained, and some discrepancies with the experimental data are discussed. Possible production of radioactive isotopes in the spallation reactions is also analyzed, i.e., the 6,8He energy spectra.
Proton capture reactions on Mg isotopes are significant in the Mg-Al cycle in stellar H-burning. In particular, the resonance strengths and branching ratios of low-energy resonances in 25Mg(
In our previous studies [Phys. Rev. C 97, 044619 (2018); Phys. Rev. C 103, 044610 (2021)], a universal odd-even staggering (OES) has been observed in extensive cross sections of isotopes not far from stability, measured for different fragmentation and spallation reactions. Four OES relations have been proposed on the basis of this OES universality. However, it is still unclear whether this OES universality and OES relations are applicable to many isotopes near the drip-lines. Here, the OES in recent experimental cross sections of very neutron-rich nuclei approaching the drip-line (from
The chiral phase transition and equation of state are studied within a novel self-consistent mean-field approximation of the two-flavor Nambu-Jona-Lasinio model. In this newly developed model, modifications to the chemical μ and chiral chemical
Extensive Air Showers (EAS) induced by cosmic ray particles of very low energies, owing to the significantly steep cosmic ray energy spectrum, dominate the secondary particle flux measured by single detectors and small shower arrays. Such arrays connected in extended networks can be used to determine potentially interesting spatial correlations between showers, which may shed new light on the nature of ultra high-energy cosmic rays. The quantitative interpretation of showers recorded by small local arrays requires a methodology that differs from that used by ordinary large EAS arrays operating in the "knee" region and above. We present "small EAS generator," a semi-analytical method for integrating cosmic ray spectra over energies of interest and summing over the mass spectra of primary nuclei in arbitrary detector configurations. Furthermore, we provide results on the EAS electron and muon fluxes and particle density spectra.
The first Water Cherenkov detector of the LHAASO experiment (WCDA-1) has been operating since April 2019. The data for the first year have been analyzed to test its performance by observing the Crab Nebula as a standard candle. The WCDA-1 achieves a sensitivity of 65 mCU per year, with a statistical threshold of 5
In this study, we investigate the Hawking radiation in higher dimensional Reissner-Nordström black holes as received by an observer located at infinity. The frequency-dependent transmission rates, which deform the thermal radiation emitted in the vicinity of the black hole horizon, are evaluated numerically. In addition to those in four-dimensional spacetime, the calculations are extended to higher dimensional Reissner-Nordström metrics, and the results are observed to be sensitive to the spacetime dimension to an extent. Generally, we observe that the transmission coefficient practically vanishes when the frequency of the emitted particle approaches zero. It increases with frequency and eventually saturates to a certain value. For four-dimensional spacetime, the above result is demonstrated to be mostly independent of the metric's parameter and the orbital quantum number of the particle, when the location of the event horizon,
This study addresses the formation of anisotropic compact star models in the background of
We calculate photon sphere
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