Chinese Physics C

Molecular picture for X₀(2900) and X₁(2900)

Jun He, Dian-Yong Chen

Published:

Abstract:
Inspired by the newly observed

\begin{document}$X_{0}(2900)$\end{document}

and

\begin{document}$X_1(2900)$\end{document}

at LHCb, the

\begin{document}$K^*\bar{D}^*$\end{document}

and

\begin{document}$K\bar{D}_1$\end{document}

interactions are studied in the quasipotential Bethe-Salpeter equation approach combined with the one-boson-exchange model. The bound and virtual states from the interactions are searched for as the poles in the complex energy plane of scattering amplitude. A bound state with

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

and a virtual state with

\begin{document}$0(1^-)$\end{document}

are produced from the

\begin{document}$K^*\bar{D}^*$\end{document}

interaction and

\begin{document}$K\bar{D}_1$\end{document}

interaction, and can be related to the

\begin{document}$X_{0}(2900)$\end{document}

and

\begin{document}$X_1(2900)$\end{document}

observed at LHCb, respectively. A bound state with

\begin{document}$I(J^P)=0(1^+)$\end{document}

and a virtual state with

\begin{document}$I(J^P)=0(2^+)$\end{document}

are also predicted from the

\begin{document}$K^*\bar{D}^*$\end{document}

interaction with the same

\begin{document}$\alpha$\end{document}

value to reproduce the

\begin{document}$X_{0,1}(2900)$\end{document}

, which can be searched in future experiments.

Rescattering mechanism of weak decays of double-charm baryons

Jia-Jie Han, Hua-Yu Jiang, Wei Liu, Zhen-Jun Xiao, Fu-Sheng Yu

Published: , doi: 10.1088/1674-1137/abec68

Abstract:
The doubly charmed baryon

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

was recently observed by LHCb via the decay processes of

\begin{document}$ \Xi_{cc}^{++}\to \Lambda_c^+ K^-\pi^+\pi^+ $\end{document}

and

\begin{document}$ \Xi_c^+\pi^+ $\end{document}

. These discovery channels were successfully predicted in the framework that the short-distance contributions are calculated under the factorization hypothesis and the long-distance contributions are estimated using the rescattering mechanism for the final-state-interaction effects. In this paper, we illustrate the above framework in details by systematic studies on the two-body baryonic decays

\begin{document}$ {\cal{B}}_{cc}\to{\cal{B}}_{c}P $\end{document}

involving the doubly charmed baryons

\begin{document}$ {\cal{B}}_{cc} = (\Xi_{cc}^{++} , \Xi_{cc}^+,\Omega_{cc}^+) $\end{document}

, the singly charmed baryons

\begin{document}$ {\cal{B}}_{c} = ({\cal{B}}_{\bar{3}}, {\cal{B}}_{6}) $\end{document}

and the light pseudoscalar mesons

\begin{document}$ P = (\pi,K,\eta_{1,8}) $\end{document}

.

Interpretation of the Galactic gamma-ray excess with the dark matter indicated by ⁸Be and ⁴He anomalous transitions

Lian-Bao Jia, Tong Li

Published:

Abstract:
The long-standing Galactic center gamma-ray excess could be explained by GeV dark matter (DM) annihilation, while the DM interpretation seems in tension with recent joint limits from different astronomical scale observations, such as dwarf spheroidal galaxies, the Milky Way halo and galaxy groups/clusters. Motivated by ⁸Be and ⁴He anomalous transitions with possible new interactions mediated by a vector boson X, we consider a small fraction of DM mainly annihilating into a pair of on-shell vector boson

\begin{document}$X X$\end{document}

followed by

\begin{document}$X \to e^+ e^-$\end{document}

in this paper. The Galactic center gamma-ray excess is explained by this DM cascade annihilation. The gamma rays are mainly from Inverse Compton Scattering emission, and the DM cascade annihilation could be compatible with joint astrophysical limits and meanwhile be allowed by the AMS-02 positron observation. The direct detection of this model is also discussed.

Change of the ⁷Be half-life in host media

Farshid Gholamian, Reza Sarhaddi, Mohammad Mehdi Firoozabadi

Published:

Abstract:
First-principle calculations within the density functional theory framework are used to study the probability of electron capture of the ⁷Be nucleus. For this purpose, electron density at the ⁷Be nucleus is computed in Al, Au, Pd, Pt, and Pb environments. Our results show that the half-life of ⁷Be has been changed by implanting ⁷Be in host environments. Electron affinity of the media and confinement effects are responsible for changing the half-life of ⁷Be nucleus. Moreover, electric potential at the ⁷Be nucleus is calculated. Results show that variations of the electric potential are usually consistent with electron density at the ⁷Be nucleus.

Phenomenological studies on the $\bar{B}^0\rightarrow [K^-\pi^+]_{S/V}[\pi^+\pi^-]_{V/S} \rightarrow K^-\pi^+\pi^+\pi^-$ decay

Jing-Juan Qi, Zhen-Yang Wang, Zhu-Feng Zhang, Xin-Heng Guo

Published: , doi: 10.1088/1674-1137/abeb06

Abstract:
Within the quasi-two-body decay model, we study the localized

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

violation and branching fraction of the four-body decay

\begin{document}$\bar{B}^0\rightarrow [K^-\pi^+]_{S/V}[\pi^+\pi^-]_{V/S} \rightarrow K^-\pi^+\pi^-\pi^+$\end{document}

when

\begin{document}$K^-\pi^+$\end{document}

and

\begin{document}$\pi^-\pi^+$\end{document}

pair invariant masses are

\begin{document}$0.35<m_{K^-\pi^+}<2.04 \; \mathrm{GeV}$\end{document}

and

\begin{document}$0<m_{\pi^-\pi^+}<1.06\; \mathrm{GeV}$\end{document}

, with the pairs being dominated by the

\begin{document}$\bar{K}^*_0(700)^0$\end{document}

,

\begin{document}$\bar{K}^*(892)^0$\end{document}

,

\begin{document}$\bar{K}^*(1410)^0$\end{document}

,

\begin{document}$\bar{K}^*_0(1430)$\end{document}

and

\begin{document}$\bar{K}^*(1680)^0$\end{document}

, and

\begin{document}$f_0(500)$\end{document}

,

\begin{document}$\rho^0(770)$\end{document}

,

\begin{document}$\omega(782)$\end{document}

and

\begin{document}$f_0(980)$\end{document}

resonances, respectively. When dealing with the dynamical functions of these resonances,

\begin{document}$f_0(500)$\end{document}

,

\begin{document}$\rho^0(770)$\end{document}

,

\begin{document}$f_0(980)$\end{document}

and

\begin{document}$\bar{K}^*_0(1430)$\end{document}

are modeled with the Bugg model, Gounaris-Sakurai function, Flatté formalism and LASS lineshape, respectively, while others are described by the relativistic Breit-Wigner function. Adopting the end point divergence parameters

\begin{document}$\rho_A\in[0,0.5]$\end{document}

and

\begin{document}$\phi_A\in[0,2\pi]$\end{document}

, our predicted results are

\begin{document}$\mathcal{A_{CP}}(\bar{B}^0\rightarrow K^-\pi^+\pi^+\pi^-)\in[-0.365,0.447]$\end{document}

and

\begin{document}$\mathcal{B}(\bar{B}^0\rightarrow K^-\pi^+\pi^+\pi^-)\in [6.11,185.32]\times10^{-8}$\end{document}

based on the hypothetical

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

structures for the scalar mesons in the QCD factorization approach. Meanwhile, we calculate the

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

violating asymmetries and branching fractions of the two-body decays

\begin{document}$\bar{B}^0\rightarrow SV(VS)$\end{document}

and all the individual four-body decays

\begin{document}$\bar{B}^0\rightarrow SV(VS) \rightarrow K^-\pi^+\pi^-\pi^+$\end{document}

, respectively. Our theoretical results for the two-body decays

\begin{document}$\bar{B}^0\rightarrow \bar{K}^*(892)^0$\end{document}

\begin{document}$f_0(980)$\end{document}

,

\begin{document}$\bar{B}^0\rightarrow \bar{K}^*_0(1430)^0$\end{document}

\begin{document}$\omega(782)$\end{document}

,

\begin{document}$\bar{B}^0\rightarrow \bar{K}^*(892)^0f_0(980)$\end{document}

,

\begin{document}$\bar{B}^0\rightarrow \bar{K}^*_0(1430)^0\rho$\end{document}

, and

\begin{document}$\bar{B}^0\rightarrow\bar{K}^*_0(1430)^0\omega$\end{document}

are consistent with the available experimental data, with the remaining predictions awaiting the tests in future examinations with high precision.

The effects of pre-equilibrium emission and secondary decay on the determination of freeze-out volume at intermediate energies

Hui-Xiao Duan, Dong-Hai Zhang, Fan Zhang, Hai-Shun Wu

Published: , doi: 10.1088/1674-1137/abec39

Abstract:
The effects of pre-equilibrium emission and secondary decay on the determination of freeze-out volume are investigated by using the isospin-dependent quantum molecular dynamics model accompanied by the statistical decay model GEMINI. Small-mass projectiles and large-mass targets with central collisions are studied at intermediate energies. It is found that the proton yields of pre-equilibrium emission are smaller than those of secondary decay. However, the determination of freeze-out volume from the proton yields is more easily affected by pre-equilibrium emission. It is also found that the percent of proton yields in freeze-out stage is approximately 50%.

Importance of the heavy-quarks longitudinal structure function measurements at future circular collider energies

G.R. Boroun

Published:

Abstract:
In this article, we consider the ratio of structure functions for heavy quark pair production at low values of

\begin{document}$ x $\end{document}

. The importance of this ratio for charm and beauty pair production is examined according to the Hadron Electron Ring Accelerator (HERA) data. The behavior of these ratios considers due to the hard-pomeron behavior of the gluon distribution function. The results are in good agreement with respect to the HERA data. Expanding this data to the range of new energies underscore the importance of these measurements for heavy quarks. The ratio of charm and beauty structure functions at the proposed Large Hadron electron Collider (LHeC) is considered as a function of invariant center-of-mass energy. For top pair production this ratio is extracted with known kinematics of the LHeC and Future Circular Collider electron-hadron (FCC-eh) colliders. Comparison of the results obtained for the ratio of top structure functions in LHeC and FCC-eh are proportional to the specified inelasticity

\begin{document}$ y $\end{document}

range.

Just Accepted