Search for mixing of D0 and its antiparticle using neural networks

Mixing is a process in which a particle spontaneously turns into its antiparticle. The Standard Model of particle physics at the box diagram level predicts that mixing of a D0 should occur approximately once every ten billion decays, while other theories predict much larger mixing rates. Measurement of the mixing rate of the D0 is an important test of the Standard Model. If mixing rates are larger than what the Standard Model predicts, this could be evidence of physics beyond the Standard Model and would be a major physics discovery. Since the D0 has zero electric charge and a lifetime of only 4×10-13 seconds, limitations in current elementary particle detector technology require examination of the decay products of the D0. Some other processes have decay products that are similar to the decay products resulting from the mixing of a D0, so it is necessary to distinguish these processes. In this analysis neural networks are used to help determine whether a D0 decay involved mixing or another process. Neural networks are models of complicated functions that, given a number of inputs, will attempt to predict the value of one or more outputs. In this study, the inputs consist of observables measured by the BaBar detector at the Stanford Linear Accelerator Center. The neural network output is binary, with 1 representing the signal candidates and 0 representing all background events. The signal mode is a D0 decaying into K+, an electron, and an antineutrino, while the D0 normally decays into K-, a positron, and a neutrino. In this study we use the neural network computer program MLPfit. MLPfit requires training data which is used to develop the neural network. This training data consists of inputs that are known to produce a certain output. These neural networks were trained with MLPfit using Monte Carlo simulation data from the BaBar experiment. The goal is to produce a neural network that will provide a cleaner data sample with fewer background events than the neural network that is currently being used in the experiment. Comparisons show neural networks trained by MLPfit are comparable to the neural network that is currently being used in the experiment. Advisor: Richard D. KassSigma XiArts and Sciences Undergraduate Research Scholarshi

Survivorship and Growth of Seedlings and Saplings in Urban Forests

Research in 1993, 2003, and 2013 showed high rates of tree mortality and low rates of recruitment (new trees) in Portland, Oregon’s Forest Park. To determine if the lack of young trees was an urban phenomenon, we added three control sites in the Mount Hood National Forest in 2013. Last summer, seedlings and saplings were measured at all sites in Forest Park, the Ancient Forest Preserve, and at the control sites. Seedlings are trees less than 2 meters tall, and saplings are trees greater than 2 meters tall but having a dbh of less than 10cm. The 2018 data was compared to that collected in 2013. We measured dbh (diameter at breast height) of saplings and the basal area for seedlings, as well as the tree height and the height of the lowest living branch. In 2018, the control sites had significantly more live trees, more coniferous trees, more shade tolerant trees, and more seedlings and saplings. We also found that the seedlings and saplings in 2018 had a greater diameter at the control sites than the urban sites. We found significantly more dead trees in 2018 than 2013 in Forest Park

The Apparent Velocity and Acceleration of Relativistically Moving Objects

Although special relativity limits the actual velocity of a particle to $c$, the velocity of light, the observed velocity need not be the same as the actual velocity as the observer is only aware of the position of a particle at the time in the past when it emits the detected signal. We consider the apparent speed and acceleration of a particle in two cases, one when the particle is moving with a constant speed and the other when it is moving with a constant acceleration. One curious feature of our results is that in both cases, if the actual velocity of the particle approaches $c$, then the apparent velocity approaches infinity when it is moving toward the observer and $c/2$ when it is moving away from the observer.Comment: 9 pages, LaTeX forma

Weak Coulomb blockade effect in quantum dots

We develop the general non-equilibrium theory of transport through a quantum dot, including Coulomb Blockade effects via a 1/N expansion, where N is the number of scattering channels. At lowest order we recover the Landauer formula for the current plus a self-consistent equation for the dot potential. We obtain the leading corrections and compare with earlier approaches. Finally, we show that to leading and next leading order in 1/N there is no interaction correction to the weak localization, in contrast to previous theories, but consistent with experiments by Huibers et al. [Phys. Rev. Lett. 81, 1917 (1998)], where N=4.Comment: 4 pages, 2 figures. Published versio

A river of salt

Author Posting. © The Oceanography Society, 2015. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 28, no. 1 (2015): 40-45, doi:10.5670/oceanog.2015.04.Terrestrial rivers are a well-known part of the global water cycle, and there has been recent discussion of “atmospheric rivers” that transport vast quantities of moisture from the tropical ocean to mid-latitudes in transient weather systems. Complementary “salt rivers” within the ocean are an equally important part of the global water cycle. They help define the ocean’s methods of returning water to where it is needed to maintain sea level and the global water cycle. One part of the Salinity Processes in the Upper-ocean Regional Study (SPURS) focused on the North Atlantic surface salinity maximum, where high evaporation rates remove freshwater from the ocean surface and leave dissolved salts behind. Much of the effort is devoted to understanding how that salty water disperses through lateral and vertical mixing processes. One important exit path is simple advection within the general circulation, which in the central Atlantic means the wind-driven “Sverdrup” circulation. Evaporation results in high salinity within the flow, marking a subsurface salt river within the ocean. Here, we examine the river’s structure as revealed in the average salinity field of the North Atlantic. Mid-ocean salinity maxima provide a unique opportunity to use an isohaline control volume approach for analyzing the mixing processes that disperse the high-salinity plume.RWS was supported by grants NNX12AF59G from NASA and 1129646 from the National Science Foundation. AB was supported by a Summer Student Fellowship from the Woods Hole Oceanographic Institution

Pride and Prejudice: Annotated with Reading Strategies

This book contains Jane Austen\u27s entire classic Pride and Prejudice with the addition of over 200 reading strategy experiences to help readers with BEFORE, DURING, and AFTER reading strategies that students can practice and learn with. Each chapter has multiple strategies embedded within the chapter to assist readers to become more active and purposeful readers. Additional resources such as links to free audio versions and online tools are also provided along with suggestions on how to use versions for electronic book readers to improve the reading experience and access information. This public domain story was first published as a book in 1813, and even today is on many reading lists for High Schools and Colleges. Students and teachers can use this text to assist readers needing extra guidance with their purposeful reading strategies or just an instructional or practice resource.https://digitalcommons.unf.edu/secondary_resources/1002/thumbnail.jp

From dual-unitary to biunitary: a 2-categorical model for exactly-solvable many-body quantum dynamics

Dual-unitary brickwork circuits are an exactly-solvable model for many-body chaotic quantum systems, based on 2-site gates which are unitary in both the time and space directions. Prosen has recently described an alternative model called 'dual-unitary interactions round-a-face', which we here call 'clockwork', based on 2-controlled 1-site unitaries composed in a non-brickwork structure, yet with many of the same attractive global properties. We present a 2-categorical framework that simultaneously generalizes these two existing models, and use it to show that brickwork and clockwork circuits can interact richly, yielding new types of generalized heterogeneous circuits. We show that these interactions are governed by quantum combinatorial data, which we precisely characterize. These generalized circuits remain exactly-solvable and we show that they retain the attractive features of the original models such as single-site correlation functions vanishing everywhere except on the causal light-cone. Our presented framework allows us to directly extend the notion of solvable initial states to these biunitary circuits, which are shown to result in maximal entanglement growth and exact thermalization after finitely many time steps under biunitary circuit dynamics.Comment: 29 page