Chinese Physics C

An improved semi-empirical relationship for cluster radioactivity

Yanzhao Wang, Fengzhu Xing, Yang Xiao, Jianzhong Gu

Published:

Abstract:
An improved semi-empirical relationship for cluster radioactivity half-lives is proposed by introducing an accurate charge radius formula and an analytic expression of the preformation probability. Then, the cluster radioactivity half-lives for the daughter nuclei around ²⁰⁸Pb or its neighbors and the ¹²C radioactivity half-life of ¹¹⁴Ba are calculated within the improved semi-empirical relationship. It is shown that the accuracy of the new relationship is improved significantly compared to its predecessor. In addition, the cluster radioactivity half-lives that are experimentally unavailable for the trans-lead and trans-tin nuclei are predicted by the new semi-empirical formula. These predictions might be useful for searching for the new cluster emitters of the two islands in future experiments.

Dynamics of k-essence in loop quantum cosmology

Jiali Shi, Jian-Pin Wu

Published:

Abstract:
In this paper, we study the dynamics of k-essence in loop quantum cosmology (LQC). The study indicates that the loop quantum gravity (LQG) effect plays a key role only in the early epoch of the universe and is diluted at the later stage. The fixed points in LQC are basically consistent with that in standard Friedmann-Robertson-Walker (FRW) cosmology. For most of the attractor solutions, the stability conditions in LQC are in agreement with that for the standard FRW universe. But for some special fixed point, more tighter constraints are imposed thanks to the LQG effect.

Higgsino asymmetry and direct-detection constraints of light dark matter in the NMSSM with non-universal Higgs masses

Kun Wang, Jingya Zhu, Quanlin Jie

Published: , doi: 10.1088/1674-1137/**/*/******

Abstract:
In this work, we study the direct-detection constraints of light dark matter in the next-to minimal supersymmetric standard model (NMSSM) with non-universal Higgs masses (NUHM), especially the correlation between higgsino asymmetry and spin-dependent (SD) cross section. Finally, we get the following conclusions: (i) The SD cross section is proportional to the square of higgsino asymmetry in dark matter

\begin{document}$\tilde{\chi}^0_1$\end{document}

in the NMSSM-NUHM, thus is small for highly singlino-dominated dark matter. (ii) The higgsino-mass parameter

\begin{document}$\mu_{\rm{eff}}$\end{document}

is smaller than about

\begin{document}$335\;{\rm{GeV}}$\end{document}

in the NMSSM-NUHM due to the current muon g-2 constraint, but our scenario with light dark matter can still be alive under current constraints including the direct detection of dark matter in the spin-dependent channel. (iii) With a sizeable higgsino component in the light dark matter, the higgsino asymmetry and SD cross section can be sizeable, but dark matter relic density is always small, thus it can escape the direct detections. (iv) Light dark matter in the

\begin{document}$h_2$\end{document}

- and Z-funnel annihilation channels with sufficient relic density can be covered by future LUX-ZEPLIN (LZ) 7-ton in SD detections. (v) The spin-independent (SI) cross section is dominated by

\begin{document}$h_1$\end{document}

- and

\begin{document}$h_2$\end{document}

-exchanging channels, which can even cancel with each other for some samples, leaving SI cross section smaller by a few magnitudes than that of individual one channel.

Polarized light-by-light scattering at the CLIC induced by axion-like particles

S.C. İnan, A.V. Kisselev

Published:

Abstract:
The light-by-light (LBL) scattering with initial polarized Compton backscattered photons at the CLIC, induced by axion-like particles (ALPs), is investigated. The total cross sections are calculated, assuming CP-even coupling of the pseudoscalar ALP to photons. The 95% C.L. exclusion region for the ALP mass

\begin{document}$m_a$\end{document}

and its coupling constant f is presented. The results are compared with previously obtained CLIC bounds for the unpolarized case. It is shown that the bounds on f for the polarized beams in the region

\begin{document}$m_a = 1000 - 2000 \;{\rm{GeV}}$\end{document}

, with the collision energy 3000 GeV and integrated luminosity 4000 fb

\begin{document}$^{-1}$\end{document}

, are on average 1.5 times stronger than the bounds for the unpolarized beams. Herewith, our CLIC bounds are stronger than all current exclusion regions for

\begin{document}$m_a > 80$\end{document}

GeV. In particular, they are more restrictive than the limits which follow from the ALP-mediated LBL scattering at the LHC.

Production of super-heavy nuclei in cold fusion reactions

V. Yu. Denisov, I. Yu. Sedykh

Published:

Abstract:
The model for the cold-fusion reactions related to the synthesis of super-heavy nuclei in collisions of heavy projectile-nuclei with ²⁰⁸Pb target nucleus is discussed. In the framework of this model the production of the compound nucleus by two paths through, the di-nuclear system and the fusion way, are taken into account simultaneously. The formation of the compound nucleus in the framework of the di-nuclear system is related to the transfer of nucleons from the light nucleus to the heavy one. The fusion way is linked to the sequential evolution of the nuclear shape from the system of contacting nuclei to the compound nucleus. It is shown that the compound nucleus is mainly formed by the fusion way in the cold-fusion reactions. The landscape of the potential energy related to the fusion path is discussed in detail. This landscape for very heavy nucleus-nucleus systems has the intermediate state, which is linked to the formation of both the compound nucleus and the quasi-fission fragments. The decay of the intermediate state is taken into account in the calculation of the compound nucleus production cross sections and the quasi-fission cross sections. The values of the cold-fusion cross sections obtained in the model are well agreed with the experimental data.

α-decay study of ²¹⁸Ac and ²²¹Th in ⁴⁰Ar+¹⁸⁶W reaction

Wei HUA, Zhiyuan ZHANG, Long MA, Zaiguo GAN, Huabin YANG, Minghui HUANG, Chunli YANG, Mingming ZHANG, Yulin TIAN, Xiaohong ZHOU, Cenxi Yuan, Caiwan SHEN, Long ZHU

Published:

Abstract:
The ²¹⁸Ac and ²²¹Th nuclide were produced via the heavy-ion induced fusion evaporation reaction ⁴⁰Ar + ¹⁸⁶W. Their decay properties were studied with the help of the gas-filled recoil spectrometer SHANS and the digital data acquisition system. The cross section ratio between ²²²Pa and ²¹⁸Ac was extracted to be 0.69(9) experimentally. Two new possible α decay branches were suggested to ²²¹Th. The valence neutron configurations for the daughter ²¹⁷Ra were discussed by the hindrance factors.

Study of the dinuclear system for ²⁹⁶119 superheavy compound nucleus in the fusion reactions

J. Mohammadi, O. N. Ghodsi

Published:

Abstract:
This investigation seeks to find an appropriate dinuclear system for the formation of

\begin{document}${}^{296}$\end{document}

119 superheavy compound nucleus. By studying driving potential and measuring the capture cross section of the reactions, the evolution of the dinuclear system can be understood. In this study, we have obtained capture, fusion and evaporation residue cross section and the survival probability at energies near the Coulomb barrier for four reactions consists of:

\begin{document}$^{45}$\end{document}

Sc +

\begin{document}$^{251}$\end{document}

Cf,

\begin{document}$^{42}$\end{document}

Ca +

\begin{document}$^{254}$\end{document}

Es,

\begin{document}$^{39}$\end{document}

K +

\begin{document}$^{257}$\end{document}

Fm, and

\begin{document}$^{38}$\end{document}

Ar +

\begin{document}$^{258}$\end{document}

Md. Our calculations show that the reaction

\begin{document}$^{38}$\end{document}

Ar +

\begin{document}$^{258}$\end{document}

Md is a suitable choice for the formation of an element with 119 protons among the studied reactions from the theoretical viewpoint.

A comparison of condensate mass of QCD vacuum between Wilson line approach and Schwinger effect

Sara Tahery, Xurong Chen, Liping Zou

Published:

Abstract:
By duality approach, we study condensate mass of QCD vacuum via dilaton wall background in presence of parameter

\begin{document}$ c $\end{document}

which represents the condensation in holographic set up. First from Wilson line calculation we find

\begin{document}$ m_0^2 $\end{document}

(condensate parameter in mixed non-local condensation) whose behavior mimics that of QCD. The value of

\begin{document}$ m_0^2 $\end{document}

that we find by this approach, is in agreement with QCD data. In the second step we consider produced mass

\begin{document}$ m $\end{document}

via Schwinger effect mechanism in presence of parameter

\begin{document}$ c $\end{document}

. We show that generally vacuum condensation contribute mass dominantly and produced mass via Schwinger effect is suppressed by

\begin{document}$ m_0 $\end{document}

.

Thermodynamics of warped anti-de Sitter black holes under scattering of scalar field

Bogeun Gwak

Published:

Abstract:
We investigate the thermodynamics and stability of the horizons in warped anti-de Sitter black holes of the new massive gravity under the scattering of a massive scalar field. Under scattering, conserved quantities can be transferred from the scalar field to the black hole, which change the state of the black hole. We determine that the changes in the black hole are well coincident with the laws of thermodynamics. In particular, the Hawking temperature of the black hole cannot be zero in the process as per the third law of thermodynamics. Furthermore, the black hole cannot be overspun beyond the extremal condition under the scattering of any mode of the scalar field.

Weak decays of doubly heavy baryons: $ {\cal B}_{cc}\to {\cal B} D^{(*)} $

Run-Hui Li, Juan-Juan Hou, Bei He, Ya-Ru Wang

Published:

Abstract:
The discovery of

\begin{document}$ \Xi_{cc}^{++} $\end{document}

inspires the new interest in studying the doubly heavy baryons. In this paper the weak decays of a doubly charm baryons

\begin{document}$ {\cal B}_{cc} $\end{document}

to a light baryon

\begin{document}$ {\cal B} $\end{document}

and a charm meson

\begin{document}$ D^{(*)} $\end{document}

(either a pseudoscalar or a vector one) are calculated. Following our previous work, we calculate the short distance contributions under the factorization hypothesis and the long distance contributions are modeled as the final state interactions which are calculated with the one particle exchange model. We find that the

\begin{document}$ {\cal B}_{cc}\to {\cal B} D^{*} $\end{document}

decays' branching ratios are obviously larger, since they receive contributions of more polarization states. Among the decays we investigated, the following ones have the largest branching fractions.

\begin{document}$ {\cal BR}(\Xi_{cc}^{++}\rightarrow\Sigma^{+}D^{*+}) \in [0.46 \%, 3.33 \%] $\end{document}

estimated with

\begin{document}$ \tau_{\Xi_{cc}^{++}} = 256 $\end{document}

fs,

\begin{document}$ {\cal BR}(\Xi_{cc}^{+}\rightarrow\Lambda D^{*+}) \in [0.38 \%, 2.63 \%] $\end{document}

and

\begin{document}$ {\cal BR}(\Xi_{cc}^{+}\rightarrow\Sigma^{0} D^{*+}) \in [0.45 \%, 3.16 \%] $\end{document}

with

\begin{document}$ \tau_{\Xi_{cc}^+} = 45 $\end{document}

fs,

\begin{document}${\cal BR}(\Omega_{cc}^{+}\rightarrow \Xi^{0} D^{*+}) \in [0.27 \%, 1.03 \%]$\end{document}

,

\begin{document}$ {\cal BR}(\Omega_{cc}^{+}\rightarrow\Xi^{0} D^{+}) \in [0.07 \%, 0.44 \%] $\end{document}

and

\begin{document}$ {\cal BR}(\Omega_{cc}^{+}\rightarrow\Sigma^{0} D^{*+}) \in [0.06 \%, 0.45 \%] $\end{document}

with

\begin{document}$ \tau_{\Omega_{cc}^+} = 75 $\end{document}

fs. Comparing the decay widths of pure color commensurate channels with those of pure bow-tie ones, we find that the bow-tie mechanism plays an important role in charm decays.

Confinement and the global SU(3) color symmetry

Ying Chen

Published:

Abstract:
The global

\begin{document}$ SU(3) $\end{document}

color symmetry and its physical consequences are discussed. The Nöther current is actually governed by the conserved matter current of color charges if the color field generated by this charge is properly polarized. The color field strength of a charge can have a uniform part due to the nontrivial QCD vacuum field and the nonzero gluon condensate, which implies that the self-energy of a system with a net color charge is infinite and thereby cannot exist as a free state. This is precisely what the color confinement means. Accordingly, the Cornell type potential with the feature of the Casimir scaling is derived for a color singlet system composed of a static color charge and an anti-charge. The uniform color field also implies that a hadron has a minimal size and a minimal energy. Furthermore, the global

\begin{document}$ SU(3) $\end{document}

color symmetry requires that the minimal irreducible color singlet systems can only be

\begin{document}$ q\bar{q} $\end{document}

,

\begin{document}$ qqq $\end{document}

,

\begin{document}$ gg $\end{document}

,

\begin{document}$ ggg $\end{document}

,

\begin{document}$ q\bar{q}g $\end{document}

,

\begin{document}$ qqqg $\end{document}

and

\begin{document}$ \bar{q}\bar{q}\bar{q}g $\end{document}

, etc., as such a multi-quark systems can only exist as a molecular configurations if there are no other binding mechanisms.

Proton radioactivity half-lives with nuclear asymmetry factor

A. Soylu, F. Koyuncu, G. Gangopadhyay, V. Dehghani, S. A. Alavi

Published:

Abstract:
The dependence of the proton decay half-lives on nuclear asymmetry parameter has been investigated using WKB method and two types of empirical formulas. Using single-folding formalism with asymmetry dependent nuclear radius and surface diffuseness of nuclear matter, the nuclear potential and consequently the half-life are functions of the asymmetry factor. Despite small values of asymmetry in neutron deficient proton emitters, noticeable changes in half-lives are observed. Addition of an asymmetry parameter term to the two forms of empirical formulas leads to a reduction in the rms error for ground state and isomeric transitions. Noticeable reduction of about 43% is obtained for isomeric transition in the second form of empirical formula. Considering ground state transitions in two categories, odd-even and odd-odd emitters, and adopting deformation and asymmetry dependent empirical formulas, the rms decreases remarkably. The lowest values of rms errors, viz. 0.1492, 0.2312, and 0.1999, are obtained for the mentioned empirical formulas of ground state transitions of odd-even and odd-odd emitters and all isomeric transitions, respectively.

Observational constraint on the dark energy scalar field

Ming-Jian Zhang, Hong Li

Published:

Abstract:
In this paper, we study three scalar fields, quintessence field, phantom field and tachyon field, to explore the source of dark energy via the Gaussian processes method from the background and perturbation growth rate data. The corresponding reconstructions all suggest that the dark energy should be dynamical. Moreover, the quintom field, a combination between quintessence field and phantom field, is powerfully favored by the reconstruction. Their mean values indicate that the potential

\begin{document}$ V(\phi) $\end{document}

in the quintessence field is a double Exponential function,

\begin{document}$ V(\phi) $\end{document}

in phantom field is a double Gaussian function. This reconstruction can provide an important reference on the scalar field study. The two types of data both reveal that the tachyon field is at a disadvantage to describe the cosmic acceleration.

Exotic ΩΩ dibaryon states in a molecular picture

Xiao-Hui Chen, Qi-Nan Wang, Wei Chen, Hua-Xing Chen

Published:

Abstract:
We investigate the exotic

\begin{document}$\Omega\Omega$\end{document}

dibaryon states with

\begin{document}$J^P=0^+$\end{document}

and

\begin{document}$2^+$\end{document}

in a molecular picture. We construct a tensor

\begin{document}$\Omega$\end{document}

molecular interpolating current and calculate the two-point correlation function within the method of QCD sum rules. Our calculations indicate that the masses of the scalar and tensor dibaryon states are

\begin{document}$m_{\Omega\Omega, \, 0^+}=(3.33\pm 0.51) \,{\rm{GeV}}$\end{document}

and

\begin{document}$m_{\Omega\Omega,\, 2^+}=(3.15\pm0.33)\, {\rm{GeV}}$\end{document}

respectively, which are below the

\begin{document}$2m_\Omega$\end{document}

threshold. Within errors, these results are not against the existence of the loosely bound molecular

\begin{document}$\Omega\Omega$\end{document}

dibaryon states. These exotic strangeness

\begin{document}$S=-6$\end{document}

and doubly-charged

\begin{document}$\Omega\Omega$\end{document}

dibaryons, if exist, may be identified in the heavy-ion collision processes in future.

Probing tqZ anomalous couplings in the trilepton signal at the HL-LHC, HE-LHC and FCC-hh

Yao-Bei Liu, Stefano Moretti

Published:

Abstract:
We investigate the prospects for discovering the Flavour Changing Neutral Current (FCNC)

\begin{document}$ tqZ $\end{document}

couplings via two production processes yielding trilepton signals: top quark pair production

\begin{document}$ pp\to t\bar{t} $\end{document}

with one top decaying to the Z boson and one light jet and the anomalous single top plus Z boson production process

\begin{document}$ pp\to tZ $\end{document}

. We study these channels at various successors of the Large Hadron Collider (LHC), i.e., the approved High-Luminosity LHC (HL-LHC) as well as the proposed High-Energy LHC (HE-LHC) and Future Circular Collider in hadron-hadron mode (FCC-hh). We perform a full simulation for the signals and the relevant Standard Model (SM) backgrounds and obtain limits on the Branching Ratios (BRs) of

\begin{document}$ t\to qZ\; (q = u,c) $\end{document}

, eventually yielding a trilepton final state through the decay modes

\begin{document}$ t\to b W^{+}\to b\ell^{+}\nu_{\ell} $\end{document}

and

\begin{document}$ Z\to \ell^{+}\ell^{-} $\end{document}

. The upper limits on these FCNC BRs at 95% Confidence Level (CL) are obtained at the HL-LHC with

\begin{document}$ \sqrt s = 14 $\end{document}

TeV and 3 ab⁻¹, at the HE-LHC with

\begin{document}$ \sqrt s = 27 $\end{document}

TeV and 15 ab⁻¹ as well as at the FCC-hh with

\begin{document}$ \sqrt s = 100 $\end{document}

TeV and 30 ab⁻¹.

Diagonal reflection symmetries and universal four-zero texture

Masaki J. S. Yang

Published:

Abstract:
In this paper, we consider a set of new symmetry in the SM, diagonal reflection symmetries

\begin{document}$R \, m_{u,\nu}^{*} \, R = m_{u,\nu}, m_{d,e}^{*} = m_{d,e}$\end{document}

with

\begin{document}$R =$\end{document}

diag

\begin{document}$(-1,1,1)$\end{document}

. These generalized

\begin{document}$CP$\end{document}

symmetries predict the Majorana phases to be

\begin{document}$\alpha_{2,3} /2 = 0$\end{document}

or

\begin{document}$\pi /2$\end{document}

. A realization of diagonal reflection symmetries implies a broken chiral

\begin{document}$U(1)_{\rm{PQ}}$\end{document}

symmetry only for the first generations. The axion scale is suggested to be

\begin{document}$\langle {\theta_{u,d}} \rangle \sim \Lambda_{\rm{GUT}} \, \sqrt{m_{u,d} \, m_{c,s}} / v \sim 10^{12} $\end{document}

[GeV]. By combining the symmetries with the four-zero texture, the mass eigenvalues and mixing matrices of quarks and leptons are well reproduced. This scheme predicts the normal hierarchy, the Dirac phase

\begin{document}$\delta _{CP} \simeq 203^{\circ},$\end{document}

and

\begin{document}$|m_{1}| \simeq 2.5$\end{document}

or

\begin{document}$6.2 $\end{document}

[meV]. In this scheme, the type-I seesaw mechanism and a given neutrino Yukawa matrix

\begin{document}$Y_{\nu}$\end{document}

completely determine the structure of right-handed neutrino mass

\begin{document}$M_{R}$\end{document}

. An

\begin{document}$u-\nu$\end{document}

unification predicts mass eigenvalues to be

\begin{document}$ (M_{R1} \, , M_{R2} \, , M_{R3}) = (O (10^{5}) \, , O (10^{9}) \, , O (10^{14})) $\end{document}

[GeV].

Anisotropic stellar structures in the f(T) theory of gravity with quintessence via embedding approach

Allah Ditta, Mushtaq Ahmad, Ibrar Hussain, G. Mustafa

Published:

Abstract:
This work suggests a new quintessence anisotropic compact stars model in the

\begin{document}$f(T)$\end{document}

gravity by using the off-diagonal tetrad and the power-law as

\begin{document}$f(T)=\beta T^n$\end{document}

, where T being the scalar torsion and

\begin{document}$\beta$\end{document}

and n are some real constants. The acquired field equations incorporating the anisotropic matter source along with the quintessence field, in the

\begin{document}$f(T)$\end{document}

gravity, are investigated by making use of the specific character of the scalar torsion T for the observed stars

\begin{document}${\rm{PSRJ1614}}-2230$\end{document}

,

\begin{document}$4U 1608-52$\end{document}

,

\begin{document}${\rm{Cen}} X-3$\end{document}

,

\begin{document}${\rm{EXO1785}}-248$\end{document}

, and

\begin{document}$SMC X-1$\end{document}

. It is suggested that all the stellar structures under examination are advantageously independent of any central singularity and are stable. Diverse physical features which are crucially important for the emergence of the stellar structures are conferred with comprehensive graphical analysis.

Longitudinal Dynamics from Hydrodynamics with an Order Parameter

Shu Lin, Gezheng Zhou

Published:

Abstract:
We study coupled dynamics of hydrodynamic fields and order parameter in the presence of nontrivial longitudinal flow using the chiral fluid dynamics model. We find the longitudinal expansion provides an effective relaxation for the order parameter, which equilibrates in an oscillatory fashion. Similar oscillations are also visible in hydrodynamic degrees of freedom through coupled dynamics. The oscillations are reduced when dissipation is present. We also find the quark density initially peaked at the boundary of boost invariant region moves toward forward rapidity with the peak velocity correlated with velocity of longitudinal expansion. The peak gets broadened during the evolution. The corresponding chemical potential rises due to simultaneous dropping of density and temperature. We compare the cases with and without dissipation for the order parameter, and also the standard hydrodynamics without order parameter. We find the corresponding effect on temperature and chemical potential can be understood from the conservation laws and different speed of equilibration of order parameter in the three cases.

Origin of the hardening in AMS-02 nuclei spectra at a few hundred GV

Jia-Shu Niu

Published:

Abstract:
Many experiments have confirmed the spectral hardening in a few hundred GV of cosmic ray (CR) nuclei spectra, and 3 different origins have been proposed: the primary source acceleration, the propagation, and the superposition of different kinds of sources. In this work, the break power law has been employed to fit each of the AMS-02 nuclei spectra directly when the rigidity greater than 45 GV. The fitting results of the break rigidity and the spectral index differences less and greater than the break rigidity show complicated relationships among different nuclei species, which could not been reproduced naturally by a simple primary source scenario or a propagation scenario. However, with a natural and simple assumption, the superposition of different kinds of sources could have the potential to explain the fitting results successfully. CR nuclei spectra from one single experiment in future (such as DAMPE) will provide us the opportunity to do cross checks and reveal the properties of the different kinds of sources.

Just Accepted