Naturalness in the Dark at the LHC

We revisit the Twin Higgs scenario as a "dark" solution to the little hierarchy problem, identify the structure of a minimal model and its viable parameter space, and analyze its collider implications. In this model, dark naturalness generally leads to Hidden Valley phenomenology. The twin particles, including the top partner, are all Standard-Model-neutral, but naturalness favors the existence of twin strong interactions -- an asymptotically-free force that confines not far above the Standard Model QCD scale -- and a Higgs portal interaction. We show that, taken together, these typically give rise to exotic decays of the Higgs to twin hadrons. Across a substantial portion of the parameter space, certain twin hadrons have visible and often displaced decays, providing a potentially striking LHC signature. We briefly discuss appropriate experimental search strategies.Comment: 64 pages, 10 figures; v2: minor changes, references adde

Evaluating Virtual Reality Use in Academic Library-Supported Course Integrations: Methodology and Initial Findings

This poster presents the methodology and initial findings of a mixed-methods research project currently underway at the University of Oklahoma Libraries, which evaluates how immersive virtual reality (VR) technology impacts student learning in the context of library-supported course integrations. It uses a combination of pre/post surveys, semi-structured interviews, and video review sessions to look at impact on student self-efficacy and their embodied practices of knowledge production with VR. Initial findings suggest that VR classroom activities should be designed keeping in mind how VR technology can enhance spatial cognitive tasks.N

Challenges and Strategies for Educational Virtual Reality

Virtual reality (VR) is a rich visualization and analytic platform that furthers the library’s mission of providing access to all forms of information and supporting pedagogy and scholarship across disciplines. Academic libraries are increasingly adopting VR technology for a variety of research and teaching purposes, which include providing enhanced access to digital collections, offering new research tools, and constructing new immersive learning environments for students. This trend suggests that positive technological innovation is flourishing in libraries, but there remains a lack of clear guidance in the library community on how to introduce these technologies in effective ways and make them sustainable within different types of institutions. In June 2018, the University of Oklahoma hosted the second of three forums on the use of 3D and VR for visualization and analysis in academic libraries, as part of the project Developing Library Strategy for 3D and Virtual Reality Collection Development and Reuse(LIB3DVR), funded by a grant from the Institute of Museum and Library Services. This qualitative study invited experts from a range of disciplines and sectors to identify common challenges in the visualization and analysis of 3D data, and the management of VR programs, for the purpose of developing a national library strategy

(How Much) Does a Private WAN Improve Cloud Performance?

The buildout of private Wide Area Networks (WANs) by cloud providers allows providers to extend their network to more locations and establish direct connectivity with end user Internet Service Providers (ISPs). Tenants of the cloud providers benefit from this proximity to users, which is supposed to provide improved performance by bypassing the public Internet. However, the performance impact of private WANs is not widely understood. To isolate the impact of a private WAN, we measure from globally distributed vantage points to a large cloud provider, comparing performance when using its worldwide WAN and when forcing traffic to instead use the public Internet. The benefits are not universal. While 40% of our vantage points saw improved performance when using the WAN, half of our vantage points did not see significant performance improvement, and 10% had better performance over the public Internet. We find that the benefits of the private WAN tend to improve with client-to-server distance, but that the benefits (or drawbacks) to a particular vantage point depend on specifics of its geographic and network connectivity

The Grizzly, February 28, 2008

Tragedy Strikes at Northern Illinois University • Safety at Ursinus College in Light of the NIU Massacre • Anti-HIV Gel Fails Clinical Trial, Opens Doors • Investigating the Seven-Day Itch • Great Wall vs. China Jade: Local Chinese Dining • Third Annual CoSA Celebration Hits Ursinus in April • Review of SPINTfest at UC • Opinions: NME Scandal: An Outsider\u27s Take; Why Kosovo\u27s Independence Matters • Strong Champs for UC Swim • Gymnastics Prepares for Nationalshttps://digitalcommons.ursinus.edu/grizzlynews/1757/thumbnail.jp

Strong field effects on emission line profiles: Kerr black holes and warped accretion disks

If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole.Comment: 22 pages, 8 figures. Accepted for publication in Ap

The Grizzly, April 10, 2008

Baby Dies from Lack of Medical Attention, Parents Charged • Relay is Here! • Dancing at Lughnasa Opens at UC • Yes, It\u27s a Positions Article • Airband\u27s 25th Raises $3100 for the Laurel House • Senior\u27s Helpful Hints for Class Registration • Glancing at the Future of Collegeville • Men\u27s Golf Swings into Season • Track Teams Win Goucher Classichttps://digitalcommons.ursinus.edu/grizzlynews/1761/thumbnail.jp

The Grizzly, February 7, 2008

Cafe Owner Advises Mindful Consumerism • More Money in Your Pocket? • Ledger\u27s Death Still Leaves Questions • NY Times Reporter Discusses Climate Issues at Focus the Nation • Arctic Mammals Battle Climate Change • Modern Menstruation Alternatives: The Menstrual Cup • Wismer Student Restaurant Welcomes New Turnstile • Things I Wish I Knew as a Freshman: Local Hot Spots • Satchmo\u27s: A Unique Sub Experience • Bringing Back the High Five • Endorse This!: How Important is a Political Backing? • Women\u27s Basketball Endures Tough Loss to Muleshttps://digitalcommons.ursinus.edu/grizzlynews/1754/thumbnail.jp

Gravastars must have anisotropic pressures

One of the very small number of serious alternatives to the usual concept of an astrophysical black hole is the "gravastar" model developed by Mazur and Mottola; and a related phase-transition model due to Laughlin et al. We consider a generalized class of similar models that exhibit continuous pressure -- without the presence of infinitesimally thin shells. By considering the usual TOV equation for static solutions with negative central pressure, we find that gravastars cannot be perfect fluids -- anisotropic pressures in the "crust" of a gravastar-like object are unavoidable. The anisotropic TOV equation can then be used to bound the pressure anisotropy. The transverse stresses that support a gravastar permit a higher compactness than is given by the Buchdahl--Bondi bound for perfect fluid stars. Finally we comment on the qualitative features of the equation of state that gravastar material must have if it is to do the desired job of preventing horizon formation.Comment: V1: 15 pages; 4 figures; uses iopart.cls; V2: 16 pages; added 3 references and brief discussio