物理最新文献

As an extension of the previous work on Solar System tests of an effective loop quantum black hole, and an attempt to find more stringent constraints on the loop quantum effect, we study its effects on physical experiments and astronomical observations conducted in the Solar System. By considering light deflection, time delay, and Cassini tracking experiments at the second post-Newtonian (2PN) order for light propagation, we find that the parametrized post-Newtonian (PPN) parameter (gamma ) in the black hole strictly equals 1. Using supplementary advances for Mercury taken from the EPM2011 and INPOP10a ephemerides, we derive much improved bounds on the black hole, which strengthen constraints on the loop quantum effect by ten times. Since such quantum effects are more likely to be observable in strong-field regimes, we estimate a preliminary bound on the loop quantum effect in these regimes based on results from EHT observations, discuss future prospects of other tests (e.g., extreme mass-ratio inspiral systems), and compare these strong-field constraints with those from the Solar System. It is worth noting that primordial black holes might provide a promising way to identify the loop quantum effect. Solar system experiments are probably not applicable for probing the quantum effect signal.

We report a feasibility study of the hyperon semileptonic decay (varLambda rightarrow pe^{-} {bar{nu }}_{e}) by using a fast simulation software package at STCF. With an anticipated integrated luminosity of 3.4 trillion (J/psi ) per year at a center-of-mass energy of 3.097 GeV, the statistical sensitivity of the branching fraction is determined to be 0.15%. The statistical sensitivities of form factors (g_{av}) and (g_w) are determined to be 0.4% and 2.15%, respectively. The projected sensitivity of (|V_{us}|) is obtained by combining this result with (g_1(0)) from Lattice QCD, to be 0.9%, including the systematic uncertainty from the LQCD input and the statistical uncertainties of input branching fraction and form factors. The precise measurement to be obtained at STCF will provide a rigorous test of the Standard Model.

In recent years, many optical industries have shown interest in employing diamond-like carbon (DLC) coatings in their products. DLC layers were successfully deposited using a low frequency pulsed magnetron sputtering system on glass substrates at room temperature. Post-thermal treatments were performed on the coated substrates at various temperatures of 150 C, 200 C and 250 C. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) revealed significant structural changes in the DLC layers as a result of the thermal post-treatment process. Additionally, the morphology of the layers was analyzed using field emission scanning electron microscopy (FESEM). Furthermore, UV-visible spectroscopy was utilized to investigate the optical properties of the films. The optical parameters of the deposited DLC layers were subsequently calculated. The results demonstrated that the optical properties of the coated DLC films could be effectively tuned through post-thermal treatment at relatively low temperatures.

This review summarizes the state of knowledge of the (^{12})C+(^{12})C fusion reaction and its impact on stellar carbon burning environments.

Photovoltaic arrays often operate in complex and harsh environments, making them susceptible to various types and severities of faults. To improve the diagnostic accuracy of PV array faults under adverse conditions, this paper proposes a fault diagnosis model integrating MIC feature selection with the MBKA-VMD-Transformer approach. Firstly, the MIC is employed to rank feature importance and conduct preliminary feature screening. Secondly, addressing the limitations of the traditional BKA in global exploration and local exploitation, several enhancements are introduced: SPM chaotic mapping, integration of sine–cosine algorithm, an adaptive inertia weight factor with cosine variation, and a tangent flight strategy. These modifications significantly enhance the optimization performance of the algorithm. Subsequently, the improved Black-winged Kite Algorithm is utilized to optimize the critical hyperparameters of VMD, using the ratio of Permutation Entropy to Mutual Information Entropy as the fitness function. The optimized VMD performs feature decomposition, and the intrinsic mode function with the highest energy is selected as the input to enhance feature representation. Finally, the MBKA-VMD-Transformer fault diagnosis model is constructed. Ablation and comparative experiments demonstrate that the model achieves a simulation diagnosis accuracy of 98.87% and a physical sample accuracy of 98.89%, representing significant performance improvements over the original Transformer model.

In this work, we study the E1 decay processes, (^3P_1) (rightarrow ) (^3S_1gamma ) and (^3S_1) (rightarrow ) (^3P_1gamma ), in the framework of Bethe–Salpeter equation and calculate their decay widths. We have used algebraic forms of the Salpeter wave functions obtained through the analytic solutions of the mass spectral equations for the ground and excited states of (^3S_1) and (^3P_1) equal mass charmonia in approximate harmonic oscillator basis to do analytic calculations of their decay widths. These decay widths have been compared with data and other models.

Taking the stable and neutron-rich oxygen and calcium isotopes as cores, we investigate the structure of multi-(Lambda ) hypernuclei with the Skyrme Hartree–Fock–Bogoliubov model. So far, the observed rare double-(Lambda ) hypernuclei events can only provide information for the S-wave (Lambda Lambda ) interaction, but not for the P-wave. Therefore, in this paper we perform several trials of the strength of P-wave (Lambda Lambda ) interaction, and discuss its effect on the properties for the multi-(Lambda ) hypernuclei. We find that different strengths of P-wave interaction will influence the (Lambda ) hyperon drip line in the neutron-rich hypernuclei, but not much in the hypernuclei with a stable core. The diffused (Lambda ) hyperon mean-field potential in the neutron-rich core makes the single (Lambda ) orbits more bound than in the stable core. Thus, the (Lambda ) continuum states are easier to be pulled down to be weakly bound states with attractive P-wave interaction strength as more (Lambda ) hyperons are added.

This work explores the connection between neural networks and cloaking systems. Specifically, it focuses on achieving bifunctional cloaking of thermal and electric fields using the wave equation and heat conduction equation. The parameters of neural networks, including the activation function, the bias function, and the weight functions, are incorporated to enhance the design of the bifunctional cloaking mechanism. The primary aim is to address various practical challenges, such as cloaking and shielding, by offering a novel approach to simplify and optimize bifunctional cloaking. A significant advantage of this principle is its ability to elucidate bifunctional cloaking for thermal and electric fields more effectively and efficiently than existing methods. To the best of our knowledge, this is the first approach to comprehensively address these challenges.

The stochastic gravitational-wave background originating from cosmic sources contains vital information about the early universe. In this work, we comprehensively study the cross-correlations between the energy-density anisotropies in scalar-induced gravitational waves and the temperature anisotropies and polarization in the cosmic microwave background. In our analysis of the angular power spectra for these cross-correlations, we consider all contributions of the local-type primordial non-Gaussianity (f_{textrm{NL}}) and (g_{textrm{NL}}) that can lead to large anisotropies. We show that the angular power spectra are highly sensitive to primordial non-Gaussianity. Furthermore, we project the sensitivity of future gravitational-wave detectors to detect such signals and, consequently, measure the primordial non-Gaussianity.

We compute all the leading-twist azimuthal spin asymmetries in the pion-proton induced Drell–Yan process. These spin asymmetries arise from convolutions of the leading-twist transverse-momentum-dependent parton distributions (TMDs) of both the incoming pion and the target proton. We employ the holographic light-front pion wave functions for the pion TMDs, while for the proton TMDs, we utilize a light-front quark-spectator model constructed by the soft-wall AdS/QCD. The gluon rescattering is crucial to predict nonzero time-reversal odd TMDs. We study the utility of a nonperturbative SU(3) gluon rescattering kernel, which extends beyond the typical assumption of perturbative U(1) gluons. Subsequently, we employ Collins–Soper scale evolution at Next-to-Leading Logarithmic precision for the TMDs evolution. Our predictions for the spin asymmetries are consistent with the available experimental data from COMPASS and other phenomenological studies. We also present the cross section for the pion-nucleus induced Drell–Yan process with the obtained pion TMDs supplemented by the TMDs of the target nucleus.