## 2019 Vol. 43, No. 6

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2019, 43(6): 063101. doi: 10.1088/1674-1137/43/6/063101

**Abstract:**

Within the framework of the Dyson-Schwinger equations and by means of Multiple Reflection Expansion, we study the effect of finite volume on the chiral phase transition in a sphere, and discuss in particular its influence on the possible location of the critical end point (CEP). According to our calculations, when we take a sphere instead of a cube, the influence of finite volume on phase transition is not as significant as previously calculated. For instance, as the radius of the spherical volume decreases from infinite to 2 fm, the critical temperature

2019, 43(6): 063102. doi: 10.1088/1674-1137/43/6/063102

**Abstract:**

One of the main problems in particle physics is to understand the origin and nature of dark matter. An exciting possibility is to consider that dark matter belongs to a new complex but hidden sector. In this paper, we assume the existence of a strongly interacting dark sector consisting of a new scalar doublet and new vector resonances, in accordance with the model recently proposed by our group. Since it was found in the previous work that it is very challenging to find the new vector resonances at the LHC, here we study the possibility of finding them at the future Compact Linear Collider (CLIC) running at

2019, 43(6): 064001. doi: 10.1088/1674-1137/43/6/064001

**Abstract:**

The potential-driving model is used to describe the driving potential distribution and to calculate the pre-neutron emission mass distributions for different incident energies in the

2019, 43(6): 064101. doi: 10.1088/1674-1137/43/6/064101

**Abstract:**

The Faddeev AGS equations for the coupled-channels

*I*= 1/2 and

*S*= 0 are solved. Using separable potentials for the

2019, 43(6): 064102. doi: 10.1088/1674-1137/43/6/064102

**Abstract:**

The Efimov (Thomas) trimers in excited

^{12}C nuclei, for which no observation exists yet, are discussed by means of analyzing the experimental data of

^{70(64)}Zn(

^{64}Ni) +

^{70(64)}Zn(

^{64}Ni) reactions at the beam energy of E/A = 35 MeV/nucleon. In heavy ion collisions,

^{8}Be and

^{12}C. For the 3

^{12}C. The interaction between any two of the 3

^{8}Be. Their interfering levels are clearly seen in the minimum relative energy distributions. Events with the three

^{8}Be are observed with the decrease of the instrumental error for the reconstructed 7.458 MeV excitation level in

^{12}C, which was suggested as the Efimov (Thomas) state.

2019, 43(6): 064103. doi: 10.1088/1674-1137/43/6/064103

**Abstract:**

Significant enhancements of

2019, 43(6): 064104. doi: 10.1088/1674-1137/43/6/064104

**Abstract:**

Within an effective Lagrangian approach and resonance model, we study the

2019, 43(6): 064105. doi: 10.1088/1674-1137/43/6/064105

**Abstract:**

The multinucleon transfer reaction in the collisions of

^{40}Ca+

^{124}Sn at

^{40}Ca +

^{112}Sn,

^{58}Ni +

^{112}Sn,

^{106}Cd +

^{112}Sn, and

^{48}Ca +

^{112}Sn are also studied. This demonstrates that the combinations of neutron-deficient projectile and target are advantageous for the production of exotic neutron-deficient nuclei near

*N*,

*Z*= 50. The charged particles' emission plays an important role at small impact parameters in the de-excitation processes of the system. The production cross sections of the exotic neutron-deficient nuclei in multinucleon transfer reactions are much larger than those measured in the fragmentation and fusion-evaporation reactions. Several new neutron-deficient nuclei can be produced in the

^{106}Cd +

^{112}Sn reaction. The corresponding production cross sections for the new neutron-deficient nuclei,

^{101, 112}Sb,

^{103}Te, and

^{106, 107}I, are 2.0 nb, 4.1 nb, 6.5 nb, 0.4

2019, 43(6): 064106. doi: 10.1088/1674-1137/43/6/064106

**Abstract:**

The newly observed isomer and ground-state band in the odd-

*Z*neutron-rich rare-earth nucleus

^{163}Eu are investigated by using the cranked shell model (CSM), with pairing treated by the particle-number conserving (PNC) method. This is the first time detailed theoretical investigations are performed of the observed 964(1) keV isomer and ground-state rotational band in

^{163}Eu. The experimental data are reproduced very well by the theoretical results. The configuration of the 964(1) keV isomer is assigned as the three-particle state

^{163}Eu. Due to its significant effect on the nuclear mean field, the high-order

^{162}Sm and

^{164}Gd, there is a 10%~15% increase of

^{163}Eu. This is explained by the pairing reduction due to the blocking of the nucleon on the proton

^{163}Eu.

2019, 43(6): 064107. doi: 10.1088/1674-1137/43/6/064107

**Abstract:**

In this study, we investigate the ion-ball screening model (model (I)), focused on the screening electrostatic potential per electron under the Wigner-Seitz approximation and the

*Q*-value correction. By considering the changes of the Coulomb free energy and the effects of strong electron screening (SES) on the

*Q*-value and the Coulomb chemical potential, we discuss the linear-response screening model (model (II)). We also analyze the influence of the SES on the

*Q*-value, the electron chemical potential, and electron energy, as well as the shell and pair effects. The antineutrino energy loss rate is found to increase by two orders of magnitude (e.g., the SES enhancement factor reaches 651.9 for model (II)) due to the SES effect.

2019, 43(6): 064108. doi: 10.1088/1674-1137/43/6/064108

**Abstract:**

Nuclear matrix elements (NME) and phase space factors (PSF) entering the half-life formulas of the double-beta decay (DBD) process are two key quantities whose accurate computation still represents a challenge. In this study, we propose a new approach of calculating these, namely the direct computation of their product as an unique formula. This procedure allows a more coherent treatment of the nuclear approximations and input parameters appearing in both quantities and avoids possible confusion in the interpretation of DBD data due to different individual expressions adopted for PSF and NME (and consequently their reporting in different units) by different authors. Our calculations are performed for both two neutrino (

2019, 43(6): 064109. doi: 10.1088/1674-1137/43/6/064109

**Abstract:**

In our previous study, the deduced Langevin equation has been applied to investigate the isoscalar giant monopole resonance. In the current study, the framework is extended to study the isovector giant dipole resonance (IVGDR). The potential well in the IVGDR is calculated by separating the neutron and proton densities based on the Hartree-Fock ground state. Subsequently, the Langevin equation is solved self-consistently, resulting in the centroid energy of the IVGDR without width. The symmetry energy around the density of 0.02 fm

^{−3}contributes the most to the potential well in the IVGDR. By comparison with the updated experimental data of IVGDR energies in spherical nuclei, the calculations within 37 sets of Skyrme functionals suggest the symmetry energy to be in the range of 8.13-9.54 MeV at a density of 0.02 fm

^{−3}.

2019, 43(6): 064110. doi: 10.1088/1674-1137/43/6/064110

**Abstract:**

A production representation of partial-wave

*S*matrix is utilized to construct low-energy elastic pion-nucleon scattering amplitudes from cuts and poles on complex Riemann sheets. Among them, the contribution of left-hand cuts is estimated using the

*S*

_{11}and

*P*

_{11}channels, as conjectured in our previous paper [Eur. Phys. J. C, 78(7): 543 (2018)], are firmly established. Specifically, the pole mass of the

*S*

_{11}hidden resonance is determined to be (895±81)−(164±23)i MeV, whereas, the virtual pole in the

*P*

_{11}channel locates at (966±18) MeV. It is found that analyses at the

*S*- and

*P*-wave channels.

2019, 43(6): 064111. doi: 10.1088/1674-1137/43/6/064111

**Abstract:**

The interaction of the pseudoscalar meson and the baryon octet is investigated by solving the Bethe-Salpeter equation in the unitary coupled-channel approximation. In addition to the Weinberg-Tomozawa term, the contribution of the

*S*-wave approximation are taken into account. In the sector of isospin

2019, 43(6): 065101. doi: 10.1088/1674-1137/43/6/065101

**Abstract:**

We propose a novel mechanism for the production of gravitational waves in the early Universe that originates from the relaxation processes induced by the QCD phase transition. While the energy density of the quark-gluon mean-field is monotonously decaying in real time, its pressure undergoes a series of violent oscillations at the characteristic QCD time scales that generate a primordial multi-peaked gravitational waves signal in the radio frequencies’ domain. The signal is an echo of the QCD phase transition that is accessible by planned measurements at the FAST and SKA telescopes.

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

Original research articles, Ietters and reviews Covering theory and experiments in the fieids of

- Particle physics
- Nuclear physics
- Particle and nuclear astrophysics
- Cosmology

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