## 2021 Vol. 45, No. 12

Display Method: |

2021, 45(12): 123101. doi: 10.1088/1674-1137/ac2359

**Abstract:**

We investigate the semi-inclusive production of hidden-charm exotic states, including the

2021, 45(12): 123102. doi: 10.1088/1674-1137/ac23d2

**Abstract:**

We thoroughly investigate both transverse momentum and threshold resummation effects on scalar-pseudoscalar pair production via quark-antiquark annihilation at the

2021, 45(12): 123103. doi: 10.1088/1674-1137/ac28f2

**Abstract:**

We construct a non-renormalizable gauge

2021, 45(12): 123104. doi: 10.1088/1674-1137/ac2a1a

**Abstract:**

In this study, the first radial excited heavy pseudoscalar and vector mesons (

2021, 45(12): 123105. doi: 10.1088/1674-1137/ac2a1d

**Abstract:**

In this study, we investigate the

2021, 45(12): 123106. doi: 10.1088/1674-1137/ac2a1e

**Abstract:**

We present the analytic calculation of two-loop master integrals that are relevant for

*tW*production at hadron colliders. We focus on the integral families with only one massive propagator. After selecting a canonical basis, the differential equations for the master integrals can be transformed into the

*d*ln form. The boundaries are determined by simple direct integrations or regularity conditions at kinematic points without physical singularities. The analytical results in this work are expressed in terms of multiple polylogarithms, and have been checked via numerical computations.

2021, 45(12): 124001. doi: 10.1088/1674-1137/ac24f6

**Abstract:**

We perform a systematic study on the effect of non-uniform track efficiency correction in higher-order cumulant analysis in heavy-ion collisions. Through analytical derivation, we find that the true values of cumulants can be successfully reproduced by the efficiency correction with an average of the realistic detector efficiency for particles with the same charges within each single phase space. The theoretical conclusions are supported by a toy model simulation by tuning the non-uniformity of the efficiency employed in the track-by-track efficiency correction method. The valid averaged efficiency is found to suppress the statistical uncertainties of the reproduced cumulants dramatically. Thus, usage of the averaged efficiency requires a careful study of phase space dependence. This study is important for carrying out precision measurements of higher-order cumulants in heavy-ion collision experiments at present and in future.

2021, 45(12): 124002. doi: 10.1088/1674-1137/ac256b

**Abstract:**

The flux-weighted average cross sections of

^{nat}Cd(γ,

*xn*)

^{115g,m,111m,109,107,105,104}Cd and

^{nat}Cd(γ,

*x*)

^{113g,112,111g,110m}Ag reactions were measured at the bremsstrahlung end-point energies of 50 and 60 MeV. The activation and off-line γ-ray spectrometric technique was carried out using the 100 MeV electron linear accelerator at the Pohang Accelerator Laboratory, Korea. The

^{nat}Cd(γ,

*xn*) reaction cross sections as a function of photon energy were theoretically calculated using the TALYS-1.95 and the EMPIRE-3.2 Malta codes. Then, the flux-weighted average cross sections were obtained from the theoretical values of mono-energetic photons. These values were compared with the flux-weighted values from the present study and were found to be in general agreement. The measured experimental reaction cross-sections and integral yields were described for cadmium and silver isotopes in the

^{nat}Cd(γ,

*xn*)

^{115g,m,111m,109,107,105,104}Cd and

^{nat}Cd(γ,

*x*)

^{113g,112,111g,110m}Ag reactions. The isomeric yield ratio (IR) of

^{115g,m}Cd in the

^{nat}Cd(γ,

*xn*) reaction was determined for the two bremsstrahlung end-point energies. The measured isomeric yield ratios of

^{115g,m}Cd in the

^{nat}Cd(γ,

*xn*) reaction were also compared with the theoretical values of the nuclear model codes and previously published literature data of the

^{116}Cd(γ,

*n*) and

^{116}Cd(

*n*, 2

*n*) reactions. It was found that the IR value increases with increasing projectile energy, which demonstrates the characteristic of excitation energy. However, the higher IR value of

^{115g,m}Cd in the

^{116}Cd(

*n*, 2

*n*) reaction compared to that in the

^{116}Cd(γ,

*n*) reaction indicates the role of compound nuclear spin alongside excitation energy.

2021, 45(12): 124101. doi: 10.1088/1674-1137/ac23d3

**Abstract:**

A systematic survey of the accurate measurements of heavy-ion fusion cross sections at extreme sub-barrier energies is performed using the coupled-channels (CC) theory that is based on the proximity formalism. This work theoretically explores the role of the surface energy coefficient and energy-dependent nucleus-nucleus proximity potential in the mechanism of the fusion hindrance of 14 typical colliding systems with negative

^{11}B+

^{197}Au,

^{12}C+

^{198}Pt,

^{16}O+

^{208}Pb,

^{28}Si+

^{94}Mo,

^{48}Ca+

^{96}Zr,

^{28}Si+

^{64}Ni,

^{58}Ni+

^{58}Ni,

^{60}Ni+

^{89}Y,

^{12}C+

^{204}Pb,

^{36}S+

^{64}Ni,

^{36}S+

^{90}Zr,

^{40}Ca+

^{90}Zr,

^{40}Ca+

^{40}Ca, and

^{48}Ca+

^{48}Ca, as well as five typical colliding systems with positive

^{12}C+

^{30}Si,

^{24}Mg+

^{30}Si,

^{28}Si+

^{30}Si,

^{36}S+

^{48}Ca, and

^{40}Ca+

^{48}Ca. It is shown that the outcomes based on the proximity potential along with the above-mentioned physical effects achieve reasonable agreement with the experimentally observed data of the fusion cross sections

Influence of different fields of mesons on the pseudospin symmetry in single-neutron resonant states

2021, 45(12): 124102. doi: 10.1088/1674-1137/ac23d4

**Abstract:**

In the framework of the relativistic mean field theory combined with the complex momentum representation method, we elucidate the pseudospin symmetry in the single-neutron resonant states and its dependence on the

2021, 45(12): 124103. doi: 10.1088/1674-1137/ac23d5

**Abstract:**

Hundreds of thousands of experimental data sets of nuclear reactions have been systematically collected, and their number is still growing rapidly. The data and their correlations compose a complex system, which underpins nuclear science and technology. We model the nuclear reaction data as weighted evolving networks for the purpose of data verification and validation. The networks are employed to study the growing cross-section data of a neutron induced threshold reaction (

*n*,2

*n*) and photoneutron reaction. In the networks, the nodes are the historical data, and the weights of the links are the relative deviation between the data points. It is found that the networks exhibit small-world behavior, and their discovery processes are well described by the Heaps law. What makes the networks novel is the mapping relation between the network properties and the salient features of the database: the Heaps exponent corresponds to the exploration efficiency of the specific data set, the distribution of the edge-weights corresponds to the global uncertainty of the data set, and the mean node weight corresponds to the uncertainty of the individual data point. This new perspective to understand the database will be helpful for nuclear data analysis and compilation.

2021, 45(12): 124104. doi: 10.1088/1674-1137/ac2421

**Abstract:**

In this work, we systematically study the two-proton (

2021, 45(12): 124105. doi: 10.1088/1674-1137/ac2425

**Abstract:**

A unified fission model is extended to study two-proton radioactivity of the ground states of nuclei, and a good agreement between the experimental and calculated half-lives is found. The two-proton radioactivity half-lives of the ground states of some probable candidates are predicted within this model by inputting the released energies taken from the AME2020 table. It is shown that the predictive accuracy of the half-lives is comparable to those of other models. Then, two-proton radioactivity of the excited states of

^{14}O,

^{17,18}Ne,

^{22}Mg,

^{29}S, and

^{94}Ag is discussed within the unified fission model and two analytical formulas. It is found that the experimental half-lives of the excited states are reproduced better within the unified fission model. Furthermore, the two formulas are not suitable for the study of two-proton radioactivity of excited states because their physical appearance deviates from the mechanism of quantum tunneling, and the parameters involved are obtained without including experimental data from the excited states.

2021, 45(12): 124106. doi: 10.1088/1674-1137/ac28f3

**Abstract:**

A systematic study on the

*α*-decay half-lives of nuclei in the range

*α*-decay processes in this region are categorized as even-even, odd A, and odd-odd nuclei. Second, they are grouped into two transitions: ground state to ground state and ground state to isomeric states. Owing to the comparison of their root-mean-square deviations (RMSD's),

2021, 45(12): 124107. doi: 10.1088/1674-1137/ac28f9

**Abstract:**

The Bayesian neural network approach has been employed to improve the nuclear magnetic moment predictions of odd-

*A*nuclei. The Schmidt magnetic moment obtained from the extreme single-particle shell model makes large root-mean-square (rms) deviations from data, i.e., 0.949

*A*nuclei with rms deviations of 0.036

2021, 45(12): 124108. doi: 10.1088/1674-1137/ac29a3

**Abstract:**

Potential energy surfaces and fission barriers of superheavy nuclei are analyzed in a macroscopic-microscopic model. The Lublin-Strasbourg Drop (LSD) model is used to obtain the macroscopic part of the energy, whereas the shell and pairing energy corrections are evaluated using the Yukawa-folded potential; a standard flooding technique is utilized to determine barrier heights. A Fourier shape parametrization containing only three deformation parameters is shown to effectively reproduce the nuclear shapes of nuclei approaching fission. In addition, a non-axial degree of freedom is taken into account to better describe the structure of nuclei around the ground state and in the saddle region. In addition to the symmetric fission valley, a new highly asymmetric fission mode is predicted in most superheavy nuclei. The fission fragment mass distributions of the considered nuclei are obtained by solving 3D Langevin equations.

2021, 45(12): 125101. doi: 10.1088/1674-1137/ac2660

**Abstract:**

We propose that fast radio bursts (FRBs) can be used as probes to constrain the possible anisotropic distribution of baryon matter in the Universe. Monte Carlo simulations show that 400 (800) FRBs are sufficient to detect the anisotropy at a 95% (99%) confidence level if the dipole amplitude has an order of magnitude of 0.01. However, more FRBs are required to tightly constrain the dipole direction. Even 1000 FRBs are insufficient to constrain the dipole direction within the angular uncertainty

2021, 45(12): 125102. doi: 10.1088/1674-1137/ac2946

**Abstract:**

We explore the theoretical possibility that dark energy density is derived from massless scalar bosons in vacuum and present a physical model for dark energy. By assuming massless scalar bosons fall into the horizon boundary of the cosmos with the expansion of the universe, we can deduce the uncertainty in the relative position of scalar bosons based on the quantum fluctuation of space-time and the assumption that scalar bosons satisfy

*P*-symmetry under the parity transformation

**ISSN** 1674-1137 **CN** 11-5641/O4

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