Multi-frequency test of dark matter annihilation into long-lived particles in Sirius

New long-lived particles produced at the colliders may escape from conventional particle detectors. Using satellites or ground telescopes, we can detect the photons generated from the annihilation of the star-captured dark matter into a pair of long-lived particles. When the propagation length of these long-lived particles surpasses the interplanetary distance between the Sun and Jupiter, it becomes unfeasible to detect such dark matter signals originating from the Sun or Jupiter on Earth. Our analysis of the dark matter-induced photons produced by prompt radiation, inverse Compton scattering, and synchrotron radiation mechanisms reveals that a decay length of about $10^{-3}$ pc for long-lived particles is required for maximum detectability. We investigate the parameters that allow the long-lived particle's lifetime to be consistent with Big Bang nucleosynthesis while also allowing it to escape the confines of our solar system. The Sirius system is proposed as a promising target for the indirect detection of such long-lived particles. Utilizing the prompt, inverse Compton scattering, and synchrotron radiation, upper limits on the dark matter-proton spin-independent and spin-dependent cross section are estimated with the Fermi-LAT null-signal observation and the capabilities of the upcoming Square Kilometre Array radio telescope.Comment: 30 pages, 6 figures, JCAP accepte

Mirror QCD phase transition as the origin of the nanohertz Stochastic Gravitational-Wave Background detected by the Pulsar Timing Arrays

Recent independent announcements by several collaborations have shown strong evidence of a Stochastic Gravitational-Wave Background (SGWB) detected through Pulsar Timing Arrays (PTAs). In this study, we investigate the implications of a first-order phase transition occurring within the early universe's dark quantum chromodynamics (dQCD) epoch, specifically within the framework of the mirror twin Higgs dark sector model. Our analysis indicates a distinguishable SGWB signal originating from this phase transition, which can explain the measurements obtained by PTAs. Remarkably, a significant portion of the parameter space within the mirror twin Higgs model that accounts for the SGWB signal also effectively resolves the existing tensions in both the $H_0$ and $S_8$ measurements in Cosmology. This intriguing correlation suggests a possible common origin for these three phenomena. Furthermore, the parameter region, $0.2 < \Delta N_{\rm eff} < 0.5$, where the mirror dark matter component constitutes less than $30\%$ of the total dark matter abundance, can accommodate all current cosmological observations and PTA measurements.Comment: 6 pages, 3 figure

Exploring Mirror Twin Higgs Cosmology with Present and Future Weak Lensing Surveys

We explore the potential of precision cosmological data to study non-minimal dark sectors by updating the cosmological constraint on the mirror twin Higgs model (MTH). The MTH model addresses the Higgs little hierarchy problem by introducing dark sector particles. In this work, we perform a Bayesian global analysis that includes the latest cosmic shear measurement from the DES three-year survey and the Planck CMB and BAO data. In the early Universe, the mirror baryon and mirror radiation behave as dark matter and dark radiation, and their presence modifies the Universe's expansion history. Additionally, the scattering between mirror baryon and photon generates the dark acoustic oscillation process, suppressing the matter power spectrum from the cosmic shear measurement. We demonstrate how current data constrain these corrections to the $\Lambda$CDM cosmology and find that for a viable solution to the little hierarchy problem, the proportion of MTH dark matter cannot exceed about $30\%$ of the total dark matter density, unless the temperature of twin photon is less than $30\%$ of that of the standard model photon. While the MTH model is presently not a superior solution to the observed $H_0$ tension compared to the $\Lambda$CDM+$\Delta N_{\rm eff}$ model, we demonstrate that it has the potential to alleviate both the $H_0$ and $S_8$ tensions, especially if the $S_8$ tension persists in the future and approaches the result reported by the Planck SZ (2013) analysis. In this case, the MTH model can relax the tensions while satisfying the DES power spectrum constraint up to $k \lesssim 10~h\rm {Mpc}^{-1}$. If the MTH model is indeed accountable for the $S_8$ and $H_0$ tensions, we show that the future China Space Station Telescope (CSST) can determine the twin baryon abundance with a $10\%$ level precision.Comment: 32 pages, 12 figures, 4 table

Genetic analysis of walnut cultivars from southwest China:Implications for germplasm improvement

Walnuts are highly valued for their rich nutritional profile and wide medicinal applications. This demand has led to the intensification of breeding activities in major walnut production areas such as southwest China, in order to develop more superior cultivars. With the increasing number of cultivars, accurate identification becomes fundamental to selecting the right cultivar for grafting, industrial processing or development of new cultivars. To ensure proper identification of cultivars and understand the genetic structure of wild and cultivated material, we genotyped 362 cultivated and wild individuals of walnut trees from southwest China (with two additional populations from Xinjiang, plus three cultivars from Canada, France and Belgium) using 36 polymorphic microsatellite loci. We found relatively low indices of genetic diversity (H(O) = 0.570, H(E) = 0.404, N(A) = 2.345) as well as a high level of clonality (>85% of cultivars), indicating reliance on genetically narrow sources of parental material for breeding. Our STRUCTURE and PCoA analyses generally delineated the two species, though considerable levels of introgression were also evident. More significantly, we detected a distinct genetic group of cultivated Juglanssigillata, which mainly comprised individuals of the popular ‘Yangbidapao’ landrace. Finally, a core set of 18 SSR loci was selected, which was capable of identifying 32 cultivars. In a nutshell, our results call for more utilization of genetically disparate material, including wild walnut trees, as parental sources to breed for more cultivars. The data reported herein will significantly contribute towards the genetic improvement and conservation of the walnut germplasm in southwest China

The Sloan Digital Sky Survey Reverberation Mapping Project: Technical Overview

The Sloan Digital Sky Survey Reverberation Mapping project (SDSS-RM) is a dedicated multi-object RM experiment that has spectroscopically monitored a sample of 849 broad-line quasars in a single 7 deg$^2$ field with the SDSS-III BOSS spectrograph. The RM quasar sample is flux-limited to i_psf=21.7 mag, and covers a redshift range of 0.1<z<4.5. Optical spectroscopy was performed during 2014 Jan-Jul dark/grey time, with an average cadence of ~4 days, totaling more than 30 epochs. Supporting photometric monitoring in the g and i bands was conducted at multiple facilities including the CFHT and the Steward Observatory Bok telescopes in 2014, with a cadence of ~2 days and covering all lunar phases. The RM field (RA, DEC=14:14:49.00, +53:05:00.0) lies within the CFHT-LS W3 field, and coincides with the Pan-STARRS 1 (PS1) Medium Deep Field MD07, with three prior years of multi-band PS1 light curves. The SDSS-RM 6-month baseline program aims to detect time lags between the quasar continuum and broad line region (BLR) variability on timescales of up to several months (in the observed frame) for ~10% of the sample, and to anchor the time baseline for continued monitoring in the future to detect lags on longer timescales and at higher redshift. SDSS-RM is the first major program to systematically explore the potential of RM for broad-line quasars at z>0.3, and will investigate the prospects of RM with all major broad lines covered in optical spectroscopy. SDSS-RM will provide guidance on future multi-object RM campaigns on larger scales, and is aiming to deliver more than tens of BLR lag detections for a homogeneous sample of quasars. We describe the motivation, design and implementation of this program, and outline the science impact expected from the resulting data for RM and general quasar science.Comment: 25 pages, submitted to ApJS; project website at http://www.sdssrm.or

Graphene-Based Nanocomposites for Energy Storage

Since the first report of using micromechanical cleavage method to produce graphene sheets in 2004, graphene/graphene-based nanocomposites have attracted wide attention both for fundamental aspects as well as applications in advanced energy storage and conversion systems. In comparison to other materials, graphene-based nanostructured materials have unique 2D structure, high electronic mobility, exceptional electronic and thermal conductivities, excellent optical transmittance, good mechanical strength, and ultrahigh surface area. Therefore, they are considered as attractive materials for hydrogen (H2) storage and high-performance electrochemical energy storage devices, such as supercapacitors, rechargeable lithium (Li)-ion batteries, Li–sulfur batteries, Li–air batteries, sodium (Na)-ion batteries, Na–air batteries, zinc (Zn)–air batteries, and vanadium redox flow batteries (VRFB), etc., as they can improve the efficiency, capacity, gravimetric energy/power densities, and cycle life of these energy storage devices. In this article, recent progress reported on the synthesis and fabrication of graphene nanocomposite materials for applications in these aforementioned various energy storage systems is reviewed. Importantly, the prospects and future challenges in both scalable manufacturing and more energy storage-related applications are discussed

Measurement of branching fractions of Λc+\Lambda_{c}^{+} decays to Σ+K+K−\Sigma^{+} K^{+} K^{-}, Σ+ϕ\Sigma^{+}\phi and Σ+K+π−(π0)\Sigma^{+} K^{+} \pi^{-}(\pi^{0})

Based on 4.5 fb$^{-1}$ data taken at seven center-of-mass energies ranging from 4.600 to 4.699 GeV with the BESIII detector at the BEPCII collider, we measure the branching fractions of $\Lambda_{c}^{+}\rightarrow\Sigma^{+}+hadrons$ relative to $\Lambda_{c}^{+}\rightarrow \Sigma^+ \pi^+ \pi^-$. Combining with the world average branching fraction of $\Lambda_{c}^{+}\rightarrow \Sigma^+ \pi^+ \pi^-$, their branching fractions are measured to be $(0.377\pm0.042\pm0.018\pm0.021)\%$ for $\Lambda_{c}^{+}\rightarrow\Sigma^{+} K^{+} K^{-}$, $(0.200\pm0.023\pm0.010\pm0.011)\%$ for $\Lambda_{c}^{+}\rightarrow\Sigma^{+} K^{+} \pi^{-}$, $(0.414\pm0.080\pm0.029\pm0.023)\%$ for $\Lambda_{c}^{+}\rightarrow\Sigma^{+}\phi$ and $(0.197\pm0.036\pm0.008\pm0.011)\%$ for $\Lambda_{c}^{+}\rightarrow\Sigma^{+}K^{+} K^{-}$(non-$\phi$). In all the above results, the first uncertainties are statistical, the second are systematic and the third are from external input of the branching fraction of $\Lambda_{c}^{+}\rightarrow \Sigma^+ \pi^+ \pi^-$. Since no signal for $\Lambda_{c}^{+}\rightarrow\Sigma^{+} K^{+} \pi^{-}\pi^{0}$ is observed, the upper limit of its branching fraction is determined to be 0.11\% at the 90$\%$ confidence level

Measurement of the cross section of e+e−→Ξ−Ξˉ+e^+e^-\rightarrow\Xi^{-}\bar\Xi^{+} at center-of-mass energies between 3.510 and 4.843 GeV

Using $e^+e^-$ collision data corresponding to a total integrated luminosity of 12.9 $fb^{-1}$ collected with the BESIII detector at the BEPCII collider, the exclusive Born cross sections and the effective form factors of the reaction $e^+e^-\rightarrow\Xi^{-}\bar\Xi^{+}$ are measured via the single baryon-tag method at 23 center-of-mass energies between 3.510 and 4.843 GeV. Evidence for the decay $\psi(3770)\rightarrow\Xi^{-}\bar\Xi^{+}$ is observed with a significance of 4.5$\sigma$ by analyzing the measured cross sections together with earlier BESIII results. For the other charmonium(-like) states $\psi(4040)$, $\psi(4160)$, $Y(4230)$, $Y(4360)$, $\psi(4415)$, and $Y(4660)$, no significant signal of their decay to $\Xi^-\bar \Xi^+$ is found. For these states, upper limits of the products of the branching fraction and the electronic partial width at the 90% confidence level are provided.Comment: 18 pages, 10 pages, 4 table

Observation of the Singly Cabibbo-Suppressed Decay Λc+→Σ−K+π+\Lambda_{c}^{+}\to \Sigma^{-}K^{+}\pi^{+}

The singly Cabibbo-suppressed decay $\Lambda_{c}^{+}\to \Sigma^{-}K^{+}\pi^{+}$ is observed for the first time with a statistical significance of $6.4\sigma$ by using 4.5 fb$^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies between 4.600 and 4.699 GeV with the BESIII detector at BEPCII. The absolute branching fraction of $\Lambda_{c}^{+}\to \Sigma^{-}K^{+}\pi^{+}$ is measured to be $(3.8\pm1.3_{\rm stat}\pm0.2_{\rm syst})\times 10^{-4}$ in a model-independent approach. This is the first observation of a Cabibbo-suppressed $\Lambda_{c}^{+}$ decay involving $\Sigma^-$ in the final state. The ratio of branching fractions between $\Lambda_{c}^{+}\to \Sigma^{-}K^{+}\pi^{+}$ and the Cabibbo-favored decay $\Lambda_{c}^{+}\to \Sigma^- \pi^+\pi^+$ is calculated to be $(0.4 \pm 0.1)s_{c}^{2}$, where $s_{c} \equiv \sin\theta_c = 0.2248$ with $\theta_c$ the Cabibbo mixing angle. This ratio significantly deviates from $1.0s_{c}^{2}$ and provides important information for the understanding of nonfactorization contributions in $\Lambda_{c}^{+}$ decays.Comment: 8 pages, 2 figure