Simplified TeV leptophilic dark matter in light of DAMPE data

Using a simplified framework, we attempt to explain the recent DAMPE cosmic $e^+ + e^-$ flux excess by leptophilic Dirac fermion dark matter (LDM). The scalar ($\Phi_0$) and vector ($\Phi_1$) mediator fields connecting LDM and Standard Model particles are discussed. Under constraints of DM relic density, gamma-rays, cosmic-rays and Cosmic Microwave Background (CMB), we find that the couplings $P \otimes S$, $P \otimes P$, $V \otimes A$ and $V \otimes V$ can produce the right bump in $e^+ + e^-$ flux for a DM mass around 1.5 TeV with a natural thermal annihilation cross-section $\sim 3 \times 10^{-26} cm^3/s$ today. Among them, $V \otimes V$ coupling is tightly constrained by PandaX-II data (although LDM-nucleus scattering appears at one-loop level) and the surviving samples appear in the resonant region, $m_{\Phi_1} \simeq 2m_{\chi}$. We also study the related collider signatures, such as dilepton production $pp \to \Phi_1 \to \ell^+\ell^-$, and muon $g-2$ anomaly. Finally, we present a possible $U(1)_X$ realization for such leptophilic dark matter.Comment: discussions added, version accepted by JHE

Probing GeV-scale MSSM neutralino dark matter in collider and direct detection experiments

Given the recent constraints from the dark matter (DM) direct detections, we examine a light GeV-scale (2-30 GeV) neutralino DM in the alignment limit of the Minimal Supersymmetric Standard Model (MSSM). In this limit without decoupling, the heavy CP-even scalar $H$ plays the role of the Standard Model (SM) Higgs boson while the other scalar $h$ can be rather light so that the DM can annihilate through the $h$ resonance or into a pair of $h$ to achieve the observed relic density. With the current collider and cosmological constraints, we find that such a light neutralino DM above 6 GeV can be excluded by the XENON-1T (2017) limits while the survivied parameter space below 6 GeV can be fully covered by the future germanium-based light dark matter detections (such as CDEX), by the Higgs coupling precison measurements or by the production process $e^+e^- \to hA$ at an electron-positron collider (Higgs factory).Comment: 15 pages, 5 figures. Discussions and references added, version accepted by PL

Quantum chaotic scattering in graphene systems in the absence of invariant classical dynamics

Peer reviewedPublisher PD

3-Meth­oxy-4-[3-(2-methyl-4-nitro-1H-imidazol-1-yl)prop­oxy]benzaldehyde

In the title mol­ecule, C15H17N3O5, the dihedral angle between the benzene and imidazole rings is 3.69 (2)°. The crystal structure is stabilized by weak inter­molecular C—H⋯O hydrogen bonds and π–π stacking inter­actions with a centroid–centroid distance of 3.614 (1) Å

A Calculation Method of X-Ray Emitted Intensity in Multi-Layer Films by Monte Carlo Simulation

A calculation method of X-ray emitted intensity in multi-layer films is proposed in this paper. The method is based on the work developed by us: (1) a simplified physical model of electron scattering and Monte Carlo evaluations in a single medium and in multi-layer media and (2) the theories and the formulae for excitation, absorption and fluorescence of characteristic X-rays. The intensity ratio of X-rays for the known thickness films, Au/Cu/Si and Cr/Ni/Si, were calculated at 20, 25 and 30 keV. Calculated results are compared with experimental values of electron microprobe analysis for the multi-layer film specimens, and the correspondence is excellent. The work lays foundations for X-ray quantitative microanalysis of multi-layer specimens

An Analytical Method of Determining Thickness of Multi-Layer Films with Electron Microprobe

In the previous work we have developed a series of theoretical corrections for calculating the emitted X-ray intensity in multi-layer films. By the use of these theories, along with careful experimental operation of the electron probe microanalysis (EPMA) and Monte Carlo iteration calculation, the thickness of each layer in multi-layer films can be determined. To test the reliability of this method, the multi-layer film specimens Au/Cu/Si, Cu/Au/Si and Ag/Cr/Si of known thicknesses were analyzed at 20, 25, 30 and 35 keV. The percentage relative errors between the thicknesses determined using the correction procedures and those measured using nuclear backscattering are less than 10%, the average value of the errors is 4.6%. The method may be extended to the calculations of determining element concentrations for the multi-layer specimens of known thicknesses

2-Amino-4-(2-chloro­phen­yl)-7,7-di­methyl-5-oxo-5,6,7,8-tetra­hydro-4H-chromene-3-carbonitrile hemihydrate

The asymmetric unit of the title compound, C18H17ClN2O2·0.5H2O, contains two organic mol­ecules and one solvent water mol­ecule. In each organic mol­ecule, the cyclo­hexene ring adopts an envelope conformation with the C atom connecting the two methyl groups on the flap; the 4H-pyran ring is nearly planar [maximum deviation = 0.113 (3) Å in one mol­ecule and 0.089 (3) Å in the other mol­ecule] and is approximately perpendicular to the chloro­phenyl ring [dihedral angle = 86.43 (15)° in one mol­ecule and 89.73 (15)° in the other mol­ecule]. Inter­molecular N—H⋯N, N—H⋯O, O—H⋯O and O—H⋯Cl hydrogen bonding is present in the crystal

A Calculation Method for Quantitative X-Ray Microanalysis for Microparticle Specimens by Monte Carlo Simulation

A calculation method for quantitative X-ray microanalysis (QXMA) for microparticle specimens of a compound with various shapes is proposed in this paper. On the basis of a simplified physical model, the scattering of electrons in particles is calculated by Monte Carlo simulation. We have derived a series of evaluation formulae of the absorption and fluorescence of characteristic X-rays for the particles with regular shapes. With the use of these theories, along with an iteration calculation, compositions of microparticle specimens can be obtained from the measured X-ray intensity ratios. In order to examine the reliability of the method, a large number of electron probe experiments and analysis calculations were carried out for the microparticle specimens of a variety of geometric shapes, dimensions and compositions. Agreement of calculated concentrations using our method with known compositions of the analyzed particle specimens is fairly good. In practical work, calculation formulae for particle specimens with irregular shapes can be replaced by those of particles with approximate regular shapes