Conformal Sector in D=6D=6 Quantum Gravity

We discuss the conformal factor dynamics in $D=6$. Accepting the proposal that higher-derivative dimensionless terms in the anomaly-induced effective action may be dropped, we obtain a superrenormalizable (like in $D=4$) effective theory for the conformal factor. The one-loop analysis of this theory gives the anomalous scaling dimension for the conformal factor and provides a natural mechanism to solve the cosmological constant problem.Comment: 9 pages, Oct 27 199

Zeta-Regularization of the O(N) Non-Linear Sigma Model in D dimensions

The O(N) non-linear sigma model in a $D$-dimensional space of the form ${\bf R}^{D-M} \times {\bf T}^M$, ${\bf R}^{D-M} \times {\bf S}^M$, or ${\bf T}^M \times {\bf S}^P$ is studied, where ${\bf R}^M$, ${\bf T}^M$ and ${\bf S}^M$ correspond to flat space, a torus and a sphere, respectively. Using zeta regularization and the $1/N$ expansion, the corresponding partition functions and the gap equations are obtained. Numerical solutions of the gap equations at the critical coupling constants are given, for several values of $D$. The properties of the partition function and its asymptotic behaviour for large $D$ are discussed. In a similar way, a higher-derivative non-linear sigma model is investigated too. The physical relevance of our results is discussed.Comment: 26 page

Electrical switching and interferometry of massive Dirac particles in topological insulators constrictions

We investigate the electrical switching of charge and spin transport in a topological insulator nanoconstriction in a four terminal device. The switch of the edge channels is caused by the coupling between edge states which overlap in the constriction and by the tunneling effects at the contacts and therefore can be manipulated by tuning the applied voltages on the split-gate or by geometrical etching. The switching mechanism can be conveniently studied by electron interferometry involving the measurements of the current in different configurations of the side gates, while the applied bias from the external leads can be tuned to obtain pure charge or pure spin currents (charge- and spin- bias configurations). Relevant signatures of quantum confinement effects, quantum size effects and energy gap are evident in the Fabry-Perot physics of the device allowing for a full characterization of the charge and spin currents. The proposed electrical switching behavior offers an efficient tool to manipulate topological edge state transport in a controllable way.Comment: 10 pages; 14 figure

Parasitic pumping currents in an interacting quantum dot

We analyze the charge and spin pumping in an interacting dot within the almost adiabatic limit. By using a non-equilibrium Green's function technique within the time-dependent slave boson approximation, we analyze the pumped current in terms of the dynamical constraints in the infinite-U regime. The results show the presence of parasitic pumping currents due to the additional phases of the constraints. The behavior of the pumped current through the quantum dot is illustrated in the spin-insensitive and in the spin-sensitive case relevant for spintronics applications

Lesson Plan, 11th Grade

TEKS (Texas Essential Knowledge and Skills): History 5B,5C Culture 26A Lesson objective(s): 1. Students will identify the similarities/differences between the NAACP platform and the Harlingen Convention. 2. Student relates movement of people and how push/pull factors drive human migration, including in the area of South Texas. 3.Students can describe the roles of reform leaders such as W.E.B. Dubois and J.T. Canales and their impact on American society. Differentiation strategies to meet diverse learner needs: - Multi sensory approach: Video, music, images, Power point presentation. - Class discussion, Q and A - Illustratio

Lesson Plan, World History, High School

TEKS (Texas Essential Knowledge and Skills): - APUSH Key Concept 1.1 Lesson objective(s): 1.Identify the Olmec and Anasazi civilizations. 2.Describe the achievements of the two civilizations. 3.Evaluate the similarities and differences of the Olmec and Anasazi. Differentiation strategies to meet diverse learner needs: -Teacher will model and explain the visual resources. -Students will create and personalize their venn diagrams