9,579 research outputs found
Formation of ultracold LiRb molecules by photoassociation near the Li (2s 2S1/2) + Rb (5p 2P1/2) asymptote
We report the production of ultracold 7Li85Rb molecules by photoassociation
(PA) below the Li (2s 2S1/2) + Rb (5p 2P1/2) asymptote. We perform PA
spectroscopy in a dual-species 7Li-85Rb magneto-optical trap (MOT) and detect
the PA resonances using trap loss spectroscopy. We observe several strong PA
resonances corresponding to the last few bound states, assign the lines and
derive the long range C6 dispersion coefficients for the Li (2s 2S1/2) + Rb (5p
2P1/2) asymptote. We also report an excited-state molecule formation rate
(P_LiRb) of ~10^7 s^-1 and a PA rate coefficient (K_PA) of ~4x10^-11 cm^3/s,
which are both among the highest observed for heteronuclear bi-alkali
molecules. These suggest that PA is a promising route for the creation of
ultracold ground state LiRb molecules.Comment: 6 page
Superspace Formulation in a Three-Algebra Approach to D=3, N=4,5 Superconformal Chern-Simons Matter Theories
We present a superspace formulation of the D=3, N=4,5 superconformal
Chern-Simons Matter theories, with matter supermultiplets valued in a
symplectic 3-algebra. We first construct an N=1 superconformal action, and then
generalize a method used by Gaitto and Witten to enhance the supersymmetry from
N=1 to N=5. By decomposing the N=5 supermultiplets and the symplectic 3-algebra
properly and proposing a new super-potential term, we construct the N=4
superconformal Chern-Simons matter theories in terms of two sets of generators
of a (quaternion) symplectic 3-algebra. The N=4 theories can also be derived by
requiring that the supersymmetry transformations are closed on-shell. The
relationship between the 3-algebras, Lie superalgebras, Lie algebras and
embedding tensors (proposed in [E. A. Bergshoeff, O. Hohm, D. Roest, H.
Samtleben, and E. Sezgin, J. High Energy Phys. 09 (2008) 101.]) is also
clarified. The general N=4,5 superconformal Chern-Simons matter theories in
terms of ordinary Lie algebras can be rederived in our 3-algebra approach. All
known N=4,5 superconformal Chern-Simons matter theories can be recovered in the
present superspace formulation for super-Lie-algebra realization of symplectic
3-algebras.Comment: 37 pages, minor changes, published in PR
Bending crystals: Emergence of fractal dislocation structures
We provide a minimal continuum model for mesoscale plasticity, explaining the
cellular dislocation structures observed in deformed crystals. Our dislocation
density tensor evolves from random, smooth initial conditions to form
self-similar structures strikingly similar to those seen experimentally -
reproducing both the fractal morphologies and some features of the scaling of
cell sizes and misorientations analyzed experimentally. Our model provides a
framework for understanding emergent dislocation structures on the mesoscale, a
bridge across a computationally demanding mesoscale gap in the multiscale
modeling program, and a new example of self-similar structure formation in
non-equilibrium systems.Comment: 4 pages, 4 figures, 5 movies (They can be found at
http://www.lassp.cornell.edu/sethna/Plasticity/SelfSimilarity.html .) In
press at Phys. Rev. Let
Characterization of the dynamic mechanical properties of low-iron float glass through Split-Hopkinson-Pressure-Bar tests
A critical review on sustainable biochar system through gasification: energy and environmental applications
This review lays great emphasis on production and characteristics of biochar through gasification. Specifically, the physicochemical properties and yield of biochar through the diverse gasification conditions associated with various types of biomass were extensively evaluated. In addition, potential application scenarios of biochar through gasification were explored and their environmental implications were discussed. To qualitatively evaluate biochar sustainability through the gasification process, all gasification products (i.e., syngas and biochar) were evaluated via life cycle assessment (LCA). A concept of balancing syngas and biochar production for an economically and environmentally feasible gasification system was proposed and relevant challenges and solutions were suggested in this review
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