Electrophilic dark matter with dark photon: from DAMPE to direct detection

The electron-positron excess reported by the DAMPE collaboration recently may be explained by an electrophilic dark matter (DM). A standard model singlet fermion may play the role of such a DM when it is stablized by some symmetries, such as a dark $U(1)_X^{}$ gauge symmetry, and dominantly annihilates into the electron-positron pairs through the exchange of a scalar mediator. The model, with appropriate Yukawa couplings, can well interpret the DAMPE excess. Naively one expects that in this type of models the DM-nucleon cross section should be small since there is no tree-level DM-quark interactions. We however find that at one-loop level, a testable DM-nucleon cross section can be induced for providing ways to test the electrophilic model. We also find that a $U(1)$ kinetic mixing can generate a sizable DM-nucleon cross section although the $U(1)_X^{}$ dark photon only has a negligible contribution to the DM annihilation. Depending on the signs of the mixing parameter, the dark photon can enhance/reduce the one-loop induced DM-nucleon cross section.Comment: 4 pages, typos are corrected, references are added as well as more discussions on direct detectio

Leptogenesis parametrized by lepton mass matrices

The conventional seesaw-leptogenesis can simultaneously explain the suppression of neutrino masses and the generation of cosmic baryon asymmetry, but usually cannot predict an unambiguous relation between these two sectors. In this work we shall demonstrate a novel left-right symmetric scenario, motivated to solve the strong CP problem by parity symmetry, where the present baryon asymmetry is determined by three charged lepton masses and a seesaw-suppressed hermitian Dirac neutrino mass matrix up to an overall scale factor. To produce the observed baryon asymmetry, this scenario requires that the neutrinos must have a normal hierarchical mass spectrum and their mixing matrix must contain a sizable Dirac CP phase. Our model can be tested in neutrino oscillation and neutrinoless double beta decay experiments.Comment: 5 pages, 2 figures. Typos are correcte

Kinematical limit analysis for a slope reinforced with one row of stabilizing piles

Stabilizing piles are commonly used to improve slope stability. The load that a pile should sustain and the associated slip surface under a prescribed factor of safety are two critical design parameters in practice. Based on the kinematically admissible failure mechanism, a limit analysis approach is introduced, which considers two potential slip surfaces that individually lie in the upslope and downslope of the piles. The explicit formulas for the upslope thrust force and downslope resistance on a pile are derived, which enables the calculation of the maximum load on a pile and the corresponding critical slip surfaces using a computer program. The maximum load and critical slip surfaces under a design factor of safety are mainly affected by soil properties and five other parameters: location of the pile row, dip angle of the slope face, action point and dip angle of the force, and improvement coefficient of the slope stability. The relevant quantitative calculation can be performed using the proposed method. Moreover, the possible failure with the upslope soil surpassing the pile top under a specified design factor of safety is significantly illustrated in the paper, which is helpful in the rational determination of the location of the pile row

A new structural wave number method to measure the dynamic characteristic parameters of viscoelastic damping material

For the viscoelastic damping material to possess excellent dissipating performance, it is crucial to obtain the dynamic characteristic parameters (DCP) of viscoelastic damping material exactly and effectively, and then to make it as input data for numerical analysis and design in the control of structural vibration. For this sake a new measurement method is presented to acquire the DCP of the viscoelastic damping material effectively in the manuscript. The properties of damping material can be achieved by substituting tested wave numbers or loss factor of composite viscoelastic damping beam (CVDB) into its inversion process of complex bending stiffness. In the present study, the loss factor of beam with unconstrained viscoelastic damping layer is measured by McDaniel and attenuation methods, respectively. And those results are compared with each other to certify the accuracy of test results firstly. Then influences of test conditions on loss factors derived from McDaniel method are studied to give some advices in the measurement. Finally the DCP of the viscoelastic damping material are obtained by the new method with complex wave number and compared with those obtained by using the resonance beam method. From the comparison it is concluded that the present proposed new approach can use limited samples to measure the DCP of the viscoelastic damping material in a wide range of frequencies effectively and conveniently

LHC Search of New Higgs Boson via Resonant Di-Higgs Production with Decays into 4W

Searching for new Higgs particle beyond the observed light Higgs boson h(125GeV) will unambiguously point to new physics beyond the standard model. We study the resonant production of a CP-even heavy Higgs state $H^0$ in the di-Higgs channel via, $gg\to H^0\to h^0h^0\to WW^*WW^*$, at the LHC Run-2 and the high luminosity LHC (HL-LHC). We analyze two types of the $4W$ decay modes, one with the same-sign di-leptons ($4W\to\ell^\pm\nu\ell^\pm\nu 4q$) and the other with tri-leptons ($4W\to\ell^\pm\nu\ell^\mp\nu\ell^\pm\nu 2q$). We perform a full simulation for the signals and backgrounds, and estimate the discovery potential of the heavy Higgs state at the LHC Run-2 and the HL-LHC, in the context of generical two-Higgs-doublet models (2HDM). We determine the viable parameter space of the 2HDM as allowed by the theoretical constraints and the current experimental limits. We systematically analyze the allowed parameter space of the 2HDM which can be effectively probed by the heavy Higgs searches of the LHC, and further compare this with the viable parameter region under the current theoretical and experimental bounds.Comment: v3: JHEP published version, 34pp, 10 Figs(36 plots) and 9 Tables. Only minor typos fixed, references added. v2: JHEP version. All results and conclusions un-changed, discussions and references added. (This update is much delayed due to author's traveling and flu.