Nonmagnetic Impurity Resonances as a Signature of Sign-Reversal Pairing in the FeAs-based Superconductors

The low energy band structure of the FeAs based superconductors is fitted by a tight binding model with two Fe ions per unit cell and two degenerate orbitals per Fe ion. Based on this, superconductivity with extended s-wave pairing symmetry of the form $\cos k_x +\cos k_y$ is examined. The local density of states near an impurity is also investigated by using T-matrix approach. For the nonmagnetic scattering potential, we found that there exist two major resonances inside the gap. The height of the resonance peaks depends on the strength of the impurity potential. These in-gap resonances are originated in the Andreev's bound states due to the quasiparticle scattering between the hole Fermi surfaces around $\Gamma$ point with positive order parameter and the electron Fermi surfaces around $M$ point with negative order parameter.Comment: 5 pages, 5 figure

China's Proposal for the Eastern Mediterranean Conflict Resolution: A "Developmental Peace"

The Eastern Mediterranean is one of the epicenters of Middle Eastern conflicts ranging from internal and bilateral to multilateral disputes. Outside powers adhere to diverse outlooks of peace initiatives. The western liberalists highlight "democratic peace", emphasizing that "democracy deficit" causes conflict. China favors the "developmental peace" proposal and argues that conflicting parties can achieve peace through domestic and regional development. China dispatched peacekeeping forces to Lebanon for humanitarian rescues for the Republic in 2020, offered developmental aid and economic assistance to Lebanon, Syria and Palestine to improve their capacity with key infrastructure and livelihood projects as the centerpiece, and participated in post-war reconstruction in the three war-torn countries as well. The "developmental peace" argument is based on China's four-decade-long Reform and Opening-up experience, a potentially new scenario for the Eastern Mediterranean conflict resolution