Search

DarkSHINE is a newly proposed fixed-target experiment initiative to search for the invisible decay of Dark Photon via missing energy/momentum signatures, based on the high repetition rate electron beam to be deployed/delivered by the Shanghai High repetition rate XFEL and Extreme light facility (SHINE). This report elaborates the baseline design of DarkSHINE experiment by introducing the physics goals, experimental setups, details of each sub-detector system technical designs, signal and backgground modelings, expected search sensitivities and future prospects, which mark an important step towards the further prototyping and technical demonstrations.

In order to explore how the ubiquitous stochastic low-frequency (SLF) variability of O-type stars is related to various stellar characteristics, we compiled a sample of 150 O-type stars observed via ground-based spectroscopic surveys, alongside photometric data obtained from the Transiting Exoplanet Survey Satellite (TESS). We analyzed 298 light curves obtained from TESS sectors 1-65 for the stars in our sample. Leveraging the spectroscopic parameters, we used Bonnsai to determine masses, radii, fractional main sequence ages, and mass-loss rates for stars of our sample. Subsequently, we identified possible correlations between the fitted parameters of SLF variability and stellar properties. Our analysis unveiled four significant correlations between the amplitude and stellar parameters, including mass, radius, fractional main sequence ages, and mass-loss rate. For stars with $M \gtrsim 30 M_{\odot}$, we observed a decrease in characteristic frequency and steepness with increasing radius. Finally, we compared various physical processes that may account for the SLF variability with our results. The observed SLF variability may arise from the combined effects of FeCZ and IGWs, with IGWs potentially more dominant in the early stages of stellar evolution, and the contribution of FeCZ becoming more significant as stars evolve. Meanwhile, our results indicate that the SLF variability of O-type stars bears certain signatures of the line-driven wind instability and granulation., Comment: 40 pages, 12 figures,accepted by Astrophysical Journal Supplement Series

We analyze the frequencies of three known roAp stars, TIC 96315731, TIC 72392575, and TIC 318007796, using the light curves from the Transiting Exoplanet Survey Satellite (TESS). For TIC 96315731, the rotational and pulsational frequencies are $0.1498360\,\mathrm{d}^{-1}$ and $165.2609\,\mathrm{d}^{-1}$, respectively. In the case of TIC 72392575, the rotational frequency is $0.25551\,\mathrm{d}^{-1}$. We detect a quintuplet of pulsation frequencies with a center frequency of $135.9233\,\mathrm{d}^{-1}$, along with two signals within the second pair of rotational sidelobes of the quintuplet separated by the rotation frequency. These two signals may correspond to the frequencies of a dipole mode. In TIC 318007796, the rotational and pulsational frequencies are $0.2475021\,\mathrm{d}^{-1}$, $192.73995\,\mathrm{d}^{-1}$, and $196.33065\,\mathrm{d}^{-1}$, respectively. Based on the oblique pulsator model, we calculate the rotation inclination $\left( i \right)$ and magnetic obliquity angle $\left( \beta \right)$ for the stars, which provides the geometry of the pulsation modes. Combining the phases of the frequency quintuplets, the pulsation amplitude and phase modulation curves, and the results of spherical harmonic decomposition, we conclude that the pulsation modes of frequency quintuplets in TIC 96315731, TIC 72392575, and TIC 318007796 correspond to distorted dipole mode, distorted quadrupole mode, and distorted dipole mode, respectively.

Gravitational echoes can be used to probe the structure of spacetime. In this paper, we investigate the gravitational echoes in different braneworld models in five-dimensional spacetime. We derive the gravitational perturbation equations of these models, and obtain the time-dependent evolution equations of the extra-dimensional and radial components. Using a Gaussian wave packet as initial data, we study the time evolution of the gravitational perturbation. By monitoring the evolution of the Gaussian wave packet, the gravitational echoes are observed whether the wave packet is generated from inside or outside the braneworld. Furthermore, we can restrict the parameters of the braneworld by calculating the strength of the first gravitational echo and using the current gravitational wave data., Comment: 29 pages, 19 figures, 1 table

Magnetic hot stars refer to the stars, which effective temperatures approximately in the range from 7,000 to 50,000 K, and with large-scale globally organized magnetic fields. These magnetic fields exhibit strengths ranging from tens of Gauss to tens of kilo-Gauss. They are key in understanding the effects caused by magnetic fields in the stellar evolution. However, there are only three magnetic hot stars studied via a combination of spectropolarimetric and asteroseismic modeling. Combined with $Transiting\;Exoplanet\;Survey\;Satellite\;(TESS)$ 1-56 sectors data sets, we provided a photometric variability and stochastic low frequency (SLF) variability study of 118 magnetic hot stars. 9 new rotating variable stars are identified. Using the Bayesian Markov Chain Monte Carlo (MCMC) framework, we fitted the morphologies of SLF variability for magnetic hot stars. Our analysis reveals that the magnetic hot stars in our sample have $\gamma < 5.5$ with the vast majority having $1 \leq \gamma \leq 3$. The $\nu_{\rm char}$ is primarily in the ranges of $0\;\text{d}^{-1} < \nu_{\rm char} < 6.3\;\text{d}^{-1}$. The amplitude of SLF variability, log$\alpha_{\rm 0}$, shows a dominant distribution ranging from 0.8 to 3. No significant correlations are observed between the luminosity and fitting parameters, suggesting no clear dependence of SLF variability on stellar mass for our sample of magnetic hot stars with masses between approximately $1.5 M_{\odot}< M < 20 M_{\odot}$. We found a significant negative correlation between the $B_{\rm p}$ and $\nu_{char}$. This suppression effect of magnetic fields on $\nu_{\rm char}$ may be a result of their inhibition of macroturbulence., Comment: 46 pages, 25 figures, Accepted by ApJ

In this work, we investigate numerical evolution of massive Kaluza-Klein (KK) modes of a Dirac field on a thick brane. We deduce the Dirac equation in five-dimensional spacetime, and obtain the time-dependent evolution equation and Schr\"odinger-like equation of the extra-dimensional component. We use the Dirac KK resonances as the initial data and study the corresponding dynamics. By monitoring the decay law of the left- and right-chiral KK resonances, we compute the corresponding lifetimes and find that there could exist long-lived KK modes on the brane. Especially, for the lightest KK resonance with a large coupling parameter and a large three momentum, it will have an extremely long lifetime., Comment: 26 pages, 12 figures

In this paper, we consider the problem of clustering graph nodes and sparsifying graph edges over distributed graphs, when graph edges with possibly edge duplicates are observed at physically remote sites. Although edge duplicates across different sites appear to be beneficial at the first glance, in fact they could make the clustering and sparsification more complicated since potentially their processing would need extra computations and communications. We propose the first communication-optimal algorithms for two well-established communication models namely the message passing and the blackboard models. Specifically, given a graph on $n$ nodes with edges observed at $s$ sites, our algorithms achieve communication costs $\tilde{O}(ns)$ and $\tilde{O}(n+s)$ ($\tilde{O}$ hides a polylogarithmic factor), which almost match their lower bounds, $\Omega(ns)$ and $\Omega(n+s)$, in the message passing and the blackboard models respectively. The communication costs are asymptotically the same as those under non-duplication models, under an assumption on edge distribution. Our algorithms can also guarantee clustering quality nearly as good as that of centralizing all edges and then applying any standard clustering algorithm. Moreover, we perform the first investigation of distributed constructions of graph spanners in the blackboard model. We provide almost matching communication lower and upper bounds for both multiplicative and additive spanners. For example, the communication lower bounds of constructing a $(2k-1)$-spanner in the blackboard with and without duplication models are $\Omega(s+n^{1+1/k}\log s)$ and $\Omega(s+n^{1+1/k}\max\{1,s^{-1/2-1/(2k)}\log s\})$ respectively, which almost match the upper bound $\tilde{O}(s+n^{1+1/k})$ for both models., Comment: This is the full version of an article published in the Proceedings of CIAC 2023

Graph sparsification is a powerful tool to approximate an arbitrary graph and has been used in machine learning over homogeneous graphs. In heterogeneous graphs such as knowledge graphs, however, sparsification has not been systematically exploited to improve efficiency of learning tasks. In this work, we initiate the study on heterogeneous graph sparsification and develop sampling-based algorithms for constructing sparsifiers that are provably sparse and preserve important information in the original graphs. We have performed extensive experiments to confirm that the proposed method can improve time and space complexities of representation learning while achieving comparable, or even better performance in subsequent graph learning tasks based on the learned embedding., Comment: Accepted and to appear in IEEE BIBM 2022 Workshop

We first present the multicolor photometry results of the rapidly rotating magnetic star HD 345439 using the Nanshan One-meter Wide-field Telescope. From the photometric observations, we derive a rotational period of 0.7699\pm0.0014 day. The light curves of HD 345439 are dominated by the double asymmetric S-wave feature that arises from the magnetic clouds. Pulsating behaviors are not observed in Sector 41 of the Transiting Exoplanet Survey Satellite. No evidence is found of the occurrence of centrifugal breakout events neither in the residual flux nor in the systematic variations at the extremum of the light curve. Based on the hypothesis of the Rigidly Rotating Magnetosphere model, we restrict the magnetic obliquity angle {$\beta$} and the rotational inclination angle $i$ so that they satisfy the approximate relation {$\beta + i \approx 105^{\circ}$}. The colour excess, extinction, and luminosity are determined to be $E_{(B-V)}=0.745\pm0.016\,$mag, $A_{V}=2.31\pm0.05\,$mag, and $\rm log\,(L/L_{\odot})=3.82\pm0.1 $dex, respectively. Furthermore, we derive the effective temperature as $T$$\rm _{eff}=22\pm1 $kK and the surface gravity as log$g=4.00\pm0.22$. The mass$ M=7.24_{-1.24}^{+1.75}\rm M_{\odot}$, radius$ R=4.44_{-1.93}^{+2.68}\rm R_{\odot}$, and age$\rm \tau_{age}=23.62\,_{-21.97}^{+4.24} $Myr are estimated from the Hertzsprung--Russell Diagram

In this work, we investigate numerical evolution of massive Kaluza-Klein (KK) modes of a scalar field in a thick brane. We derive the Klein-Gordon equation in five dimensional spacetime, and obtain the evolution equation and the Schr\"odinger-like equation. With the resonances of the scalar KK modes as the initial data, the scalar field is evolved with the maximally dissipative boundary condition. The results show that there are scalar KK resonant particles with long life on the brane, which indicates that these resonances might be viewed as one of the candidates for dark matter., Comment: 10 pages, 5 figures. improved version