Direct detection and solar capture of dark matter with momentum and velocity dependent elastic scattering

We explore the momentum and velocity dependent elastic scattering between the dark matter (DM) particles and the nuclei in detectors and the Sun. In terms of the non-relativistic effective theory, we phenomenologically discuss ten kinds of momentum and velocity dependent DM-nucleus interactions and recalculate the corresponding upper limits on the spin-independent DM-nucleon scattering cross section from the current direct detection experiments. The DM solar capture rate is calculated for each interaction. Our numerical results show that the momentum and velocity dependent cases can give larger solar capture rate than the usual contact interaction case for almost the whole parameter space. On the other hand, we deduce the Super-Kamiokande's constraints on the solar capture rate for eight typical DM annihilation channels. In contrast to the usual contact interaction, the Super-Kamiokande and IceCube experiments can give more stringent limits on the DM-nucleon elastic scattering cross section than the current direct detection experiments for several momentum and velocity dependent DM-nucleus interactions. In addition, we investigate the mediator mass's effect on the DM elastic scattering cross section and solar capture rate.Comment: 18 pages, 4 figures, 2 tables. minor changes and a reference added, published in Nuclear Physics

Metal-Free Flat Lens Using Negative Refraction by Nonlinear Four-wave Mixing

A perfect lens with unlimited resolution has always posed a challenge to both theoretical and experimental physicists. Recent developments in optical meta-materials promise an attractive approach towards perfect lenses using negative refraction to overcome the diffraction limit, improving resolution. However, those artificially engineered meta-materials usually company by high losses from metals and are extremely difficult to fabricate. An alternative proposal using negative refraction by four-wave mixing has attracted much interests recently, though most of existing experiments still require metals and none of them has been implemented for an optical lens. Here we experimentally demonstrate a metal-free flat lens for the first time using negative refraction by degenerate four-wave mixing with a thin glass slide. We realize optical lensing effect utilizing a nonlinear refraction law, which may have potential applications in microscopy

Empowerment and Entrepreneurship on WeChat: A Focus on Shared Stories of Muslim Women Entrepreneurs in China

New media entrepreneurship is already the most popular business model today. The purpose of this study is to demonstrate the motivation and strategies of Muslim women entrepreneurship on WeChat. Design/ Methods/ Methodology - Using a qualitative research design, the data for our survey was obtained from 8 female entrepreneurs in Yiwu City. The authors conduct in-depth interviews methods to enable women to express their stories and experience voluntarily and truly in entrepreneurship activities. The interview data was analyzed using thematic analysis. The study found that factors such to increase family income, intention to experience into entrepreneurial activities, and the ease of new media technology, have prompted Muslim women to start an online business. Furthermore, using WeChat, entrepreneurs and customers establish emotional connections to promote business development. Another key factor was also elaborated in this study where Muslim women strive to balance the relationship between family and their business. Implications and conclusion were also described in this research