Prospects for γγ→H\gamma \gamma \to H and γγ→W+W−\gamma \gamma \to W^{+}W^{-} measurements at the FCC-ee

We study the possibilities for the measurement of two-photon production of the Higgs boson (in the $b \bar{b}$ decay channel), and of $W^{+}W^{-}$ pairs (decaying into four jets) in $e^{+}e^{-}$ collisions at the the Future Circular Collider (FCC-ee). The processes are simulated with the PYTHIA and MADGRAPH 5 Monte Carlo codes, using the effective photon approximation for the $e^{+}e^{-}$ photon fluxes, at center-of-mass energies $\sqrt{s} =$ 160 GeV and 240 GeV. The analyses include electron-positron tagging, realistic acceptance and reconstruction efficiencies for the final-state jets, and selection criteria to remove the backgrounds. Observation of both channels is achievable with the expected few ab$^{-1}$ integrated luminosities at FCC-ee.Comment: Proceedings of the conference PHOTON 2015: International Conference on the Structure and the Interactions of the Photon including the 21th International Workshop on Photon-Photon Collisions and the International Workshop on High Energy Photon Colliders, held at Budker Institute of Nuclear Physics (BINP), Siberian Branch of Russian Academy of Science, Novosibirsk, Russia, from 15 to 19 June, 201

Charged exctions in two-dimensional transition-metal dichalcogenides - semiclassical calculation of Berry-curvature effects

We theoretically study the role of the Berry curvature on neutral and charged excitons in two-dimensional transition-metal dichalcogenides. The Berry curvature arises due to a strong coupling between the conduction and valence bands in these materials that can to great extent be described within the model of massive Dirac fermions. The Berry curvature lifts the degeneracy of exciton states with opposite angular momentum. Using an electronic interaction that accounts for non-local screening effects, we find a Berry-curvature induced splitting of $\sim 17$ meV between the 2$p_{-}$ and 2$p_{+}$ exciton states in WS$_2$, consistent with experimental findings. Furthermore, we calculate the trion binding energies in WS$_2$ and WSe$_2$ for a large variety of screening lenghts and different dielectric constants for the environment. Our approach indicates the prominent role played by the Berry curvature along with non-local electronic interactions in the understanding of the energy spectra of neutral and charged excitons in transition-metal dichalcogenides and in the the interpretation of their optical properties.Comment: 11 pages, 3 figure

Breaking the Tire Cycle Advocacy Campaign

WiLDCOAST, an environmental nonprofit on the United States-Mexico border has a program that focuses on the flow of used tires into California from Mexico was a huge burden on local communities. This program was the basis for this advocacy campaign which focuses on a legislative fix to break the tire cycle, and reduce the associated economic, public health, and environmental impacts that these tires cause. This project became state law.https://digital.sandiego.edu/npi-bpl-advocacy/1001/thumbnail.jp