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Full-Text Articles in Physics

Ultraviolet Luminosity Density Of The Universe During The Epoch Of Reionization, Ketron Mitchell-Wynne, Asantha Cooray, Yan Gong, Matthew Ashby, Timothy Dolch, Henry Ferguson, Steven Finkelstein, Norman Grogin, Dale D. Kocevski, Anton Koekemoer, Joel Primack, Joseph Smidt Sep 2015

Ultraviolet Luminosity Density Of The Universe During The Epoch Of Reionization, Ketron Mitchell-Wynne, Asantha Cooray, Yan Gong, Matthew Ashby, Timothy Dolch, Henry Ferguson, Steven Finkelstein, Norman Grogin, Dale D. Kocevski, Anton Koekemoer, Joel Primack, Joseph Smidt

Physics and Astronomy Faculty Publications

The spatial fluctuations of the extragalactic background light trace the total emission from all stars and galaxies in the Universe. A multiwavelength study can be used to measure the integrated emission from first galaxies during reionization when the Universe was about 500 million years old. Here we report arcmin-scale spatial fluctuations in one of the deepest sky surveys with the Hubble Space Telescope in five wavebands between 0.6 and 1.6 μm. We model-fit the angular power spectra of intensity fluctuation measurements to find the ultraviolet luminosity density of galaxies at redshifts greater than 8 to be log ρUV = …


Imaging Of Alignment And Structural Changes Of Carbon Disulfide Molecules Using Ultrafast Electron Diffraction, Jie Yang, Joshua Beck, Cornelis J. Uiterwaal, Martin Centurion Sep 2015

Imaging Of Alignment And Structural Changes Of Carbon Disulfide Molecules Using Ultrafast Electron Diffraction, Jie Yang, Joshua Beck, Cornelis J. Uiterwaal, Martin Centurion

Martin Centurion Publications

Imaging the structure of molecules in transient-excited states remains a challenge due to the extreme requirements for spatial and temporal resolution. Ultrafast electron diffraction from aligned molecules provides atomic resolution and allows for the retrieval of structural information without the need to rely on theoretical models. Here we use ultrafast electron diffraction from aligned molecules and femtosecond laser mass spectrometry to investigate the dynamics in carbon disulfide following the interaction with an intense femtosecond laser pulse. We observe that the degree of alignment reaches an upper limit at laser intensities below the ionization threshold, and find evidence of structural deformation, …


Resonant 𝜋⁺𝜸 → 𝜋⁺𝜋⁰ Amplitude From Quantum Chromodynamics, Raúl A. Briceño, Jozef J. Dudek, Robert G. Edwards, Christian J. Shultz, Christopher E. Thomas, David J. Wilson Jan 2015

Resonant 𝜋⁺𝜸 → 𝜋⁺𝜋⁰ Amplitude From Quantum Chromodynamics, Raúl A. Briceño, Jozef J. Dudek, Robert G. Edwards, Christian J. Shultz, Christopher E. Thomas, David J. Wilson

Physics Faculty Publications

We present the first ab initio calculation of a radiative transition of a hadronic resonance within quantum chromodynamics (QCD). We compute the amplitude for 𝜋𝜋→𝜋𝜸, as a function of the energy of the 𝜋𝜋 pair and the virtuality of the photon, in the kinematic regime where 𝜋𝜋 couples strongly to the unstable ρ resonance. This exploratory calculation is performed using a lattice discretization of QCD with quark masses corresponding to mπ ≈ 400  MeV. We obtain a description of the energy dependence of the transition amplitude, constrained at 48 kinematic points, that we can analytically continue …