6,729 research outputs found
A Quadrillion Standard Models from F-theory
We present an explicit construction of globally
consistent string compactifications that realize the exact chiral spectrum of
the Standard Model of particle physics with gauge coupling unification in the
context of F-theory. Utilizing the power of algebraic geometry, all global
consistency conditions can be reduced to a single criterion on the base of the
underlying elliptically fibered Calabi--Yau fourfolds. For toric bases, this
criterion only depends on an associated polytope and is satisfied for at least
bases, each of which defines a distinct compactification.Comment: 7 pages, double column; v3: improved and expanded discussion,
technical details deferred to an added appendi
High-throughput intensity diffraction tomography with a computational microscope
We demonstrate a motion-free intensity diffraction tomography technique that enables direct inversion of 3D phase and absorption from intensity-only measurements for weakly scattering samples. We derive a novel linear forward model, featuring slice-wise phase and absorption transfer functions using angled illumination. This new framework facilitates flexible and efficient data acquisition, enabling arbitrary sampling of the illumination angles. The reconstruction algorithm performs 3D synthetic aperture using a robust, computation and memory efficient slice-wise deconvolution to achieve resolution up to the incoherent limit. We demonstrate our technique with thick biological samples having both sparse 3D structures and dense cell clusters. We further investigate the limitation of our technique when imaging strongly scattering samples. Imaging performance and the influence of multiple scattering is evaluated using a 3D sample consisting of stacked phase and absorption resolution targets. This computational microscopy system is directly built on a standard commercial microscope with a simple LED array source add-on, and promises broad applications by leveraging the ubiquitous microscopy platforms with minimal hardware modifications
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