Dark Matter from Strong Dynamics: The Minimal Theory of Dark Baryons

As a simple model for dark matter, we propose a QCD-like theory based on $\rm{SU}(2)$ gauge theory with one flavor of dark quark. The model is confining at low energy and we use lattice simulations to investigate the properties of the lowest-lying hadrons. Compared to QCD, the theory has several peculiar differences: there are no Goldstone bosons or chiral symmetry restoration when the dark quark becomes massless; the usual global baryon number symmetry is enlarged to $\rm{SU}(2)_B$, resembling isospin; and baryons and mesons are unified together in $\rm{SU}(2)_B$ iso-multiplets. We argue that the lightest baryon, a vector boson, is a stable dark matter candidate and is a composite realization of the hidden vector dark matter scenario. The model naturally includes a lighter state, the analog of the $\eta^\prime$ in QCD, for dark matter to annihilate into to set the relic density via thermal freeze-out. Dark matter baryons may also be asymmetric, strongly self-interacting, or have their relic density set via $3 \to 2$ cannibalizing transitions. We discuss some experimental implications of coupling dark baryons to the Higgs portal.Comment: 26 pages, 16 figure

Megagauss 2.0 : a 10 capacitor system for production of megagauss fields for laser plasma experiments

textHigh magnetic fields greater than 100 Tesla applied to laser generated plasmas can generate unique and interesting conditions. High power laser systems at the University of Texas in the Center for Higher Energy Density Sciences readily produce short lived fusion plasmas in cluster targets. A strong magnetic field could increase fusion neutron yield and plasma confinement while providing a unique plasma physics environment. For this purpose, Sandia National Laboratories in collaboration with the University of Texas designed and constructed a pulsed power device to produce more than 2 megaamperes. This current produces strong magnetic fields in small coils with duration on the order of microseconds. At the University of Texas, tests with this device determined the operational characteristics. I will describe the behavior of this device with currents of approximately a megaamp and magnetic fields of more than 60 Tesla. Emphasis is placed on understanding the behavior of the fields and coils.Physic

The Fourth Amendment in the Hallway: Do Tenants Have a Constitutionally Protected Privacy Interest in the Locked Common Areas of Their Apartment Buildings?

One afternoon, a police officer spots a man driving a Cadillac through a run·down neighborhood. His interest piqued, the officer decides to follow the vehicle. The Cadillac soon comes to rest in front of an apartment building, and the driver, Jimmy Barrios-Moriera, removes a shopping bag from the trunk and enters the building. The moment Barrios-Moriera disappears within the doorway, the officer sprints after him because he knows that the door to the apartment building will automatically lock when it closes. He manages to catch the door just in time and rushes in. Barrios-Moriera is already halfway up a flight of stairs in the common hallway and ignores the police officer when he identifies himself and indicates a desire to speak with him. Barrios-Moriera continues up the stairs and sets his shopping bag on the floor beside him as he hurriedly tries to open his door. The police officer sprints up the stairs after him and arrives before Barrios-Moriera can do so. He thrusts his hand into Barrios-Moriera\u27s bag and withdraws a rectangular-shaped object wrapped in tape. He then orders Barrios-Moriera to go into his apartment, where he arrests him for possession of cocaine with intent to distribute

Contrastive Decoding Improves Reasoning in Large Language Models

We demonstrate that Contrastive Decoding -- a simple, computationally light, and training-free text generation method proposed by Li et al 2022 -- achieves large out-of-the-box improvements over greedy decoding on a variety of reasoning tasks. Originally shown to improve the perceived quality of long-form text generation, Contrastive Decoding searches for strings that maximize a weighted difference in likelihood between strong and weak models. We show that Contrastive Decoding leads LLaMA-65B to outperform LLaMA 2, GPT-3.5 and PaLM 2-L on the HellaSwag commonsense reasoning benchmark, and to outperform LLaMA 2, GPT-3.5 and PaLM-540B on the GSM8K math word reasoning benchmark, in addition to improvements on a collection of other tasks. Analysis suggests that Contrastive Decoding improves over existing methods by preventing some abstract reasoning errors, as well as by avoiding simpler modes such as copying sections of the input during chain-of-thought. Overall, Contrastive Decoding outperforms nucleus sampling for long-form generation and greedy decoding for reasoning tasks, making it a powerful general purpose method for generating text from language models.Comment: 9 figures, 11 table

Open Access Panel Discussion

Bios: Ken N. Meadows is an educational researcher with the Teaching Support Centre and Adjunct Research Faculty in the Faculty of Education at Western University. He co-ordinates scholarship of teach­ing and learning initiatives, supports librarians and staff in their research and program evaluation endeavours, and serves as Managing Editor for The Canadian Journal for the Scholarship of Teaching and Learning. His research focuses on positive faculty and stu­dent development, the impact of educational development programs, and teaching cul­tures in post-secondary institutions. He completed his Ph.D. in Psychology at Western University in 2003. Sean Lewis is the Editor-in-Chief of the Western Journal of Legal Studies and a third-year law student at Western Law. In his time on the Journal, Sean was previously a Staff Editor and Managing Editor, and has worked with the Journal’s Executive to develop a new Blog, www.wjlschambers.com, a re-designed website, and a more structured review process for articles. Prior to attending law school Sean served on the Western undergraduate political science journal, The Social Contract, and the Graduate Journal for Political Science at York University, Problematique. Founded in 2011, the Western Journal of Legal Studies is an open-access law reviewing focusing on submissions that are novel, non-obvious, and useful. The Journal has been cited by the Supreme Court of Canada and recently published an article by Canada’s Chief Justice, Beverly McLachlin. For more information, please visit the Journal’s website at: http://ir.lib.uwo.ca/uwojls/. Kelly Hatch is a Research and Instructional Librarian at the Allyn & Betty Taylor Library. Along with several of her colleagues, they support the Schulich School of Medicine and Dentistry. As part of her instruction responsibilities, Kelly has delivered several sessions on Open Access including the Canadian Institutes of Health Research (CIHR), New Principal Investigators Meeting in 2014

Probing Protoplanetary Disk Upper Atmospheres for Heating and Dust Settling using Synthetic CO Spectra

CO emission is a useful probe of the warm gas distribution in the planet forming regions of disks around Herbig Ae/Be (HAeBe) stars. We model UV fluoresced and thermally excited CO in the circumstellar disks of several HAeBes. We find indications of dust settling in the upper atmospheres of HD 141569 and HD 97048 and a correlation between PAH luminosity and gas heating in these two systems