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Full-Text Articles in Physics
Probing A Panoply Of Curvaton-Decay Scenarios Using Cmb Data, Tristan L. Smith, D. Grin
Probing A Panoply Of Curvaton-Decay Scenarios Using Cmb Data, Tristan L. Smith, D. Grin
Physics & Astronomy Faculty Works
In the curvaton scenario, primordial curvature perturbations are produced by a second field that is subdominant during inflation. Depending on how the curvaton decays [possibly producing baryon number, lepton number, or cold dark matter (CDM)], mixtures of correlated isocurvature perturbations are produced, allowing the curvaton scenario to be tested using cosmic microwave background (CMB) data. Here, a full range of 27 curvaton-decay scenarios is compared with CMB data, placing limits on the curvaton fraction at decay, rD, and the lepton asymmetry, ξlep. If baryon number is generated by curvaton decay and CDM before (or vice versa), these limits imply specific …
Pinning Susceptibility: The Effect Of Dilute, Quenched Disorder On Jamming, Amy Lisa Graves, Samer B. Nashed , '15, Elliot S. Padgett , '13, C. P. Goodrich, A. J. Liu, J. P. Sethna
Pinning Susceptibility: The Effect Of Dilute, Quenched Disorder On Jamming, Amy Lisa Graves, Samer B. Nashed , '15, Elliot S. Padgett , '13, C. P. Goodrich, A. J. Liu, J. P. Sethna
Physics & Astronomy Faculty Works
We study the effect of dilute pinning on the jamming transition. Pinning reduces the average contact number needed to jam unpinned particles and shifts the jamming threshold to lower densities, leading to a pinning susceptibility, χp. Our main results are that this susceptibility obeys scaling form and diverges in the thermodynamic limit as χp∝|ϕ−ϕ∞c|−γp where ϕ∞c is the jamming threshold in the absence of pins. Finite-size scaling arguments yield these values with associated statistical (systematic) errors γp=1.018±0.026(0.291) in d=2 and γp=1.534±0.120(0.822) in d=3. Logarithmic corrections raise the exponent in d=2 to close to the d=3 value, although the systematic errors …
Tunable Depletion Potentials Driven By Shape Variation Of Surfactant Micelles, M. D. Gratale, T. Still, C. Matyas, Z. S. Davidson, S. Lobel, Peter J. Collings, A. G. Yodh
Tunable Depletion Potentials Driven By Shape Variation Of Surfactant Micelles, M. D. Gratale, T. Still, C. Matyas, Z. S. Davidson, S. Lobel, Peter J. Collings, A. G. Yodh
Physics & Astronomy Faculty Works
Depletion interaction potentials between micron-sized colloidal particles are induced by nanometer-scale surfactant micelles composed of hexaethylene glycol monododecyl ether (C12E6), and they are measured by video microscopy. The strength and range of the depletion interaction is revealed to arise from variations in shape anisotropy of the surfactant micelles. This shape anisotropy increases with increasing sample temperature. By fitting the colloidal interaction potentials to theoretical models, we extract micelle length and shape anisotropy as a function of temperature. This work introduces shape anisotropy tuning as a means to control interparticle interactions in colloidal suspensions, and it shows how the interparticle depletion …
Possible Signatures Of Dissipation From Time-Series Analysis Techniques Using A Turbulent Laboratory Magnetohydrodynamic Plasma, D. A. Schaffner, Michael R. Brown, Ariel B. Rock , '16
Possible Signatures Of Dissipation From Time-Series Analysis Techniques Using A Turbulent Laboratory Magnetohydrodynamic Plasma, D. A. Schaffner, Michael R. Brown, Ariel B. Rock , '16
Physics & Astronomy Faculty Works
The frequency spectrum of magnetic fluctuations as measured on the Swarthmore Spheromak Experiment is broadband and exhibits a nearly Kolmogorov 5/3 scaling. It features a steepening region which is indicative of dissipation of magnetic fluctuation energy similar to that observed in fluid and magnetohydrodynamic turbulence systems. Two non-spectrum based time-series analysis techniques are implemented on this data set in order to seek other possible signatures of turbulent dissipation beyond just the steepening of fluctuation spectra. Presented here are results for the flatness, permutation entropy, and statistical complexity, each of which exhibits a particular character at spectral steepening scales which can …
Gravitational-Wave Cosmology Across 29 Decades In Frequency, P. D. Lasky, C. M.F. Mingarelli, Tristan L. Smith, J. T. Giblin Jr., E. Thrane, D. J. Reardon, R. Caldwell, M. Bailes, N.D. R. Bhat, S. Burke-Spolaor, S. Dai, J. Dempsey, G. Hobbs, M. Kerr, Y. Levin, R. N. Manchester, S. Osłowski, V. Ravi, P. A. Rosado, R. M. Shannon, R. Spiewak, W. Van Straten, L. Toomey, J. Wang, L. Wen, X. You, X. Zhu
Gravitational-Wave Cosmology Across 29 Decades In Frequency, P. D. Lasky, C. M.F. Mingarelli, Tristan L. Smith, J. T. Giblin Jr., E. Thrane, D. J. Reardon, R. Caldwell, M. Bailes, N.D. R. Bhat, S. Burke-Spolaor, S. Dai, J. Dempsey, G. Hobbs, M. Kerr, Y. Levin, R. N. Manchester, S. Osłowski, V. Ravi, P. A. Rosado, R. M. Shannon, R. Spiewak, W. Van Straten, L. Toomey, J. Wang, L. Wen, X. You, X. Zhu
Physics & Astronomy Faculty Works
Quantum fluctuations of the gravitational field in the early Universe, amplified by inflation, produce a primordial gravitational-wave background across a broad frequency band. We derive constraints on the spectrum of this gravitational radiation, and hence on theories of the early Universe, by combining experiments that cover 29 orders of magnitude in frequency. These include Planck observations of cosmic microwave background temperature and polarization power spectra and lensing, together with baryon acoustic oscillations and big bang nucleosynthesis measurements, as well as new pulsar timing array and ground-based interferometer limits. While individual experiments constrain the gravitational-wave energy density in specific frequency bands, …