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2024 No.4
Some remarks on compositeness of ${{\boldsymbol T}^{\bf +}_{\boldsymbol{cc}}} $
Chang Chen, Ce Meng, Zhiguang Xiao, Han-Qing Zheng
2024, 48(4): 043102. doi: 10.1088/1674-1137/ad1a0b
Abstract:
Recently, the LHCb experimental group found an exotic state $ T^+_{cc} $ from the $ pp \to D^0D^0\pi^+ + X $ process. A key question is whether it is just a molecule or may have a confined tetraquark ingredient. To investigate this, different methods were used, including a two-channel ($ D^{*+}D^0 $ and $ D^{*0}D^+ $) K-matrix unitarization and a single-channel Flatté-like parametrization method analyzed utilizing the pole counting rule and spectral density function sum rule. These analyses demonstrated that $ T^+_{cc} $ is a molecular state, although the possibility that there may exist an elementary ingredient cannot be excluded, according to an approximate analysis of its production rate.
Tensor force impact on shell evolution in neutron-rich Si and Ni isotopes
S.V. Sidorov, A.S. Kornilova, T.Yu. Tretyakova
2024, 48(4): 044101. doi: 10.1088/1674-1137/ad20d4
Abstract:
The influence of the tensor interaction of nucleons on the characteristics of neutron-rich silicon and nickel isotopes was studied in this work. Tensor forces are considered within the framework of the Hartree-Fock approach with the Skyrme interaction. The addition of a tensor component of interaction is shown to improve the description of the splittings between different single-particle states and decrease nucleon-nucleon pairing correlations in silicon and nickel nuclei. Special attention was directed toward the role of isovector tensor forces relevant to the interaction of like nucleons.
Reconstruction of aether scalar tensor theory for variouscosmological scenarios
Qi-Ming Fu, Meng-Ci He, Tao-Tao Sui, Xin Zhang
2024, 48(4): 045105. doi: 10.1088/1674-1137/ad2360
Abstract:
In this paper, we present several explicit reconstructions for the aether scalar tensor (AeST) theory derived from the background of the Friedmann-Lemaître-Robertson-Walker cosmological evolution. It is shown that the Einstein-Hilbert Lagrangian with a positive cosmological constant is the only Lagrangian capable of accurately replicating the exact expansion history of the Λ cold dark matter (ΛCDM) universe filled solely with dust-like matter. However, the ΛCDM-era can be produced within the framework of the AeST theory for some other fluids, including a perfect fluid with $ p=-(1/3)\rho $, multifluids, and nonisentropic perfect fluids. Moreover, we demonstrate that the ΛCDM-era can be replicated with no real matter field for the AeST theory. The cosmic evolution resulting from both the power-law and de-Sitter solutions can also be obtained.
Leptonic di-flavor and di-number violation processes at high energy ${{ {\boldsymbol\mu}^{\bf\pm}}{\boldsymbol\mu}^{\bf\pm}} $ colliders
Jin-Lei Yang, Chao-Hsi Chang, Tai-Fu Feng
2024, 48(4): 043101. doi: 10.1088/1674-1137/ad17b0
Abstract:
The leptonic di-flavor violation (LFV) processes $ \mu^\pm \mu^\pm \rightarrow e^\pm e^\pm $ and $ \mu^\pm \mu^\pm \rightarrow \tau^\pm \tau^\pm $ and leptonic di-number violation (LNV) processes $ \mu^\pm \mu^\pm \rightarrow W^\pm _iW^\pm _j $ ($ i,\;j=1,\;2 $) at same-sign high energy $ \mu^\pm \mu^\pm $ colliders are studied. The new physics (NP) factors that may play roles in these processes are highlighted by cataloging them into three types. Taking into account the experimental constraints, the processes at $ \mu^\pm\mu^\pm $ colliders are computed, and the results are presented properly. The results lead to the conclusion that observing the NP factors through the LFV and LNV processes at TeV-energy $ \mu^\pm\mu^\pm $ colliders has significant advantages that cannot be achieved elsewhere. Therefore, once the techniques for muon acceleration and collision are developed successfully, the option of building same-sign high energy muon colliders should be seriously considered.
Higgs inflation model with non-minimal coupling in hybrid Palatini approach
Brahim Asfour, Aatifa Bargach, Ahmed Errahmani, Taoufik Ouali
2024, 48(4): 045104. doi: 10.1088/1674-1137/ad1dcd
Abstract:
In this paper, we propose a hybrid metric Palatini approach in which the Palatini scalar curvature is non minimally coupled to the scalar field. We derive Einstein's field equations, i.e., the equations of motion of the scalar field. Furthermore, the background and perturbative parameters are obtained by means of Friedmann equations in the slow roll regime. The analysis of cosmological perturbations allowed us to obtain the main inflationary parameters, e.g., the scalar spectral index$ n_s $and tensor to scalar ratio r. From this perspective, as an application of our analysis, we consider the Higgs field with quartic potential, which plays the inflaton role, and show that predictions of Higgs hybrid inflation are in good agreement with recent observational data [Astron. Astrophys. 641, 61 (2020)].
Simulating gamma-ray production from cosmic rays interacting with the solar atmosphere in the presence of coronal magnetic fields
Zhe Li, Kenny C. Y. Ng, Songzhan Chen, Yuncheng Nan, Huihai He
2024, 48(4): 045101. doi: 10.1088/1674-1137/ad1cda
Abstract:
Cosmic rays can interact with the solar atmosphere and produce a slew of secondary messengers, making the Sun a bright gamma-ray source in the sky. Detailed observations with Fermi-LAT have shown that these interactions must be strongly affected by solar magnetic fields in order to produce a wide range of observational features, such as a high flux and hard spectrum. However, the detailed mechanisms behind these features are still a mystery. In this study, we tackle this problem by performing particle-interaction simulations in the solar atmosphere in the presence of coronal magnetic fields using the potential field source surface (PFSS) model. We find that low-energy (~ GeV) gamma-ray production is significantly enhanced by the coronal magnetic fields, but the enhancement decreases rapidly with energy. The enhancement directly correlates with the production of gamma rays with large deviation angles relative to the input cosmic-ray direction. We conclude that coronal magnetic fields are essential for correctly modeling solar disk gamma rays below 10 GeV, but above that, the effect of coronal magnetic fields diminishes. Other magnetic field structures are needed to explain the high-energy disk emission.
Rastall gravity: accretion disk image in the context of radiation fields and visual transformations compared to Reissner-Nordström black hole
Yu-Xiang Huang, Sen Guo, Yu Liang, Yu-Hao Cui, Qing-Quan Jiang, Kai Lin
2024, 48(4): 045102. doi: 10.1088/1674-1137/ad1feb
Abstract:
In this study, we investigated the astronomical implications of Rastall gravity, particularly its behavior amidst a radiation field compared to Reissner-Nordström (RN) black holes. We found a crucial correlation between the dynamics of the accretion disk and the parameters Q and $ N_{\rm{r}} $, which properly reflect the influence of spacetime metrics on the disk’s appearance. Elevated electric charge Q causes contraction in the disk’s orbit due to enhanced gravitational effects, while higher $ N_{\rm{r}} $ values lead to outward expansion, influenced by the attributes of the radiation field. Interestingly, the charged black holes surrounded by radiation fields exhibit distinct visual disparities from RN black holes. Brightness decreases and expansion occurs within the innermost stable circular orbit of the accretion disk with rising $ N_{\rm{r}} $ values. Our study also reveals the process by which the accretion disk transitions from a conventional disk-like structure to a hat-like form at different observation angles, with the redshift effect gradually intensifying. Moreover, the results of the considered Rastall gravity radiation field are consistent with the constraints of the gravitational lensing of the host galaxy on Rastall gravity parameters, thereby enhancing the consistency between theoretical predictions and actual observations.
Radiative capture of proton through the 14N(p,γ)15O reaction at low energy
B.F. Irgaziev, Abdul Kabir, Jameel-Un Nabi
2024, 48(4): 045103. doi: 10.1088/1674-1137/ad1b3c
Abstract:
The CNO cycle is the main source of energy in stars more massive than our Sun. This process defines the energy production, the duration of which can be used to determine the lifetime of massive stars. The cycle is an important tool for determining the age of globular clusters. Radiative proton capture via $ p + {^{14}\rm{N}}\rightarrow {^{15}\rm{O}+{\gamma}} $, at energies of astrophysical interest, is an important process in the CNO cycle. In this project, we apply a potential model to describe both non-resonant and resonant reactions in the channels where radiative capture occurs through electric $ E1 $ transitions. We employed the R-matrix method to describe the ongoing reactions via $ M1 $ resonant transitions, when it was not possible to correctly reproduce the experimental data using the potential model. The partial components of the astrophysical S-factor are calculated for all possible electric and magnetic dipole transitions in 15O. The linear extrapolated S-factor at zero energy (S(0)) agrees well with earlier reported values for all transition types considered in this work. Based on the value of the total astrophysical S-factor, depending on the collision energy, we calculate the nuclear reaction rates for $ p + {^{14}\rm{N}}\rightarrow {^{15}\rm{O}+{\gamma}} $. The computed rates agree well with the results reported in the NACRE II Collaboration and most recent existing measurements.