arXiv subjects

Daniel A. Dwyer

Publications and source records attributed to Daniel A. Dwyer.

3 recordsLinked to original sources

arXiv2017

Estimation of reactor neutrino fluxes

Reactor antineutrinos have been indispensable for our understanding of neutrino mass and mixing. At the same time, discrepancies between the observed and predicted reactor $\overlineν_{e}$ rate and energy spectra have grown as the precision of these measurements has improved. Measurements of the electrons emitted following fission result in the most precise predictions for the corresponding $\overlineν_{e}$ flux, and our understanding of the potential systematic differences between the fission $e^-$ and $\overlineν_{e}$ fluxes has improved. Measurements of individual fission daughter isotopes and their decays are fraught with uncertainties, yet still provide insight into these discrepancies. Detailed comparisons of $\overlineν_{e}$ measurements among reactors are also shedding new light on this topic.

nucl-ex↗

arXiv2013

The Improved Measurement of Electron-antineutrino Disappearance at Daya Bay

With 2.5x the previously reported exposure, the Daya Bay experiment has improved the measurement of the neutrino mixing parameter sin^2(2theta_13) = 0.089+-0.010(stat)+-0.005(syst). Reactor anti-neutrinos were produced by six 2.9 GW(th) commercial power reactors, and measured by six 20-ton target-mass detectors of identical design. A total of 234,217 anti-neutrino candidates were detected in 127 days of exposure. An anti-neutrino rate of 0.944+-0.007(stat)+-0.003(syst) was measured by three detectors at a flux-weighted average distance of 1648 m from the reactors, relative to two detectors at 470 m and one detector at 576 m. Detector design and depth underground limited the background to 5+-0.3% (far detectors) and 2+-0.2% (near detectors) of the candidate signals. The improved precision confirms the initial measurement of reactor anti-neutrino disappearance, and continues to be the most precise measurement of theta_13.

hep-ex↗

arXiv2000

Collision-Induced Decay of Metastable Baby Skyrmions

Many extensions of the standard model predict heavy metastable particles which may be modeled as solitons (skyrmions of the Higgs field), relating their particle number to a winding number. Previous work has shown that the electroweak interactions admit processes in which these solitons decay, violating standard model baryon number. We motivate the hypothesis that baryon-number-violating decay is a generic outcome of collisions between these heavy particles. We do so by exploring a 2+1 dimensional theory which also possesses metastable skyrmions. We use relaxation techniques to determine the size, shape and energy of static solitons in their ground state. These solitons could decay by quantum mechanical tunneling. Classically, they are metastable: only a finite excitation energy is required to induce their decay. We attempt to induce soliton decay in a classical simulation by colliding pairs of solitons. We analyze the collision of solitons with varying inherent stabilities and varying incident velocities and orientations. Our results suggest that winding-number violating decay is a generic outcome of collisions. All that is required is sufficient (not necessarily very large) incident velocity; no fine-tuning of initial conditions is required.

hep-ph↗