U-spin analysis of CP violation in B−B^- decays into three charged light pseudoscalar mesons

We carry out a $U$-spin symmetry analysis for CP violation in $B^-$ decays into three light $\pi^-\pi^-\pi^+$, $\pi^- K^-K^+$, $K^-K^-K^+$ and $K^- \pi^-\pi^+$ mesons. We clarify some subtle points in constructing decay amplitudes with $U=0$ formed by the two negatively charged light mesons in the final states. $U$-spin conserving momentum independent and momentum dependent decay amplitudes, and $U$-spin violating decay amplitudes due to quark mass difference are constructed.Comment: RevTex 12 pages wit no figur

Topological superconductivity at the edge of transition metal dichalcogenides

Time-reversal breaking topological superconductors are new states of matter which can support Majorana zero modes at the edge. In this paper, we propose a new realization of one-dimensional topological superconductivity and Majorana zero modes. The proposed system consists of a monolayer of transition metal dichalcogenides MX2 (M=Mo, W; X=S, Se) on top of a superconducting substrate. Based on first-principles calculations, we show that a zigzag edge of the monolayer MX2 terminated by metal atom M has edge states with strong spin-orbit coupling and spontaneous magnetization. By proximity coupling with a superconducting substrate, topological superconductivity can be induced at such an edge. We propose NbS2 as a natural choice of substrate, and estimate the proximity induced superconducting gap based on first-principles calculation and low energy effective model. As an experimental consequence of our theory, we predict that Majorana zero modes can be detected at the 120 degree corner of a MX2 flake in proximity with a superconducting substrate

The β\beta angle as the CP violating phase in the CKM matrix

The CKM matrix describing quark mixing with three generations can be parameterized by three Euler mixing angles and one CP violating phase. In most of the parameterizations, the CP violating phase chosen is not a directly measurable quantity and is parametrization dependent. In this work, we propose to use the most accurately measured CP violating angle $\beta$ in the unitarity triangleas the phase in the CKM matrix, and construct an explicit $\beta$ parameterization. We also derive an approximate Wolfenstein-like expression for this parameterization.Comment: RevTex 7 pages with one figure. Version to be published in Phys. Lett. B. arXiv admin note: substantial text overlap with arXiv:1204.123

The α\alpha, β\beta and γ\gamma parameterizations of CP violating CKM phase

The CKM matrix describing quark mixing with three generations can be parameterized by three mixing angles and one CP violating phase. In most of the parameterizations, the CP violating phase chosen is not a directly measurable quantity and is parametrization dependent. In this work, we propose to use experimentally measurable CP violating quantities, $\alpha$, $\beta$ or $\gamma$ in the unitarity triangle as the phase in the CKM matrix, and construct explicit $\alpha$, $\beta$ and $\gamma$ parameterizations. Approximate Wolfenstein-like expressions are also suggested.Comment: 14 page, 1 figur

Hazmats Transportation Network Design Model with Emergency Response under Complex Fuzzy Environment

A bilevel optimization model for a hazardous materials transportation network design is presented which considers an emergency response teams location problem. On the upper level, the authority designs the transportation network to minimize total transportation risk. On the lower level, the carriers first choose their routes so that the total transportation cost is minimized. Then, the emergency response department locates their emergency service units so as to maximize the total weighted arc length covered. In contrast to prior studies, the uncertainty associated with transportation risk has been explicitly considered in the objective function of our mathematical model. Specifically, our research uses a complex fuzzy variable to model transportation risk. An improved artificial bee colony algorithm with priority-based encoding is also applied to search for the optimal solution to the bilevel model. Finally, the efficiency of the proposed model and algorithm is evaluated using a practical case and various computing attributes