Heavy Color-Octet Particles at the LHC

Many new-physics models, especially those with a color-triplet top-quark partner, contain a heavy color-octet state. The "naturalness" argument for a light Higgs boson requires that the color-octet state be not much heavier than a TeV, and thus it can be pair-produced with large cross sections at high-energy hadron colliders. It may decay preferentially to a top quark plus a top-partner, which subsequently decays to a top quark plus a color-singlet state. This singlet can serve as a WIMP dark-matter candidate. Such decay chains lead to a spectacular signal of four top quarks plus missing energy. We pursue a general categorization of the color-octet states and their decay products according to their spin and gauge quantum numbers. We review the current bounds on the new states at the LHC and study the expected discovery reach at the 8-TeV and 14-TeV runs. We also present the production rates at a future 100-TeV hadron collider, where the cross sections will be many orders of magnitude greater than at the 14-TeV LHC. Furthermore, we explore the extent to which one can determine the color octet's mass, spin, and chiral couplings. Finally, we propose a test to determine whether the fermionic color octet is a Majorana particle.Comment: 20 pages, 9 figures; journal versio

An Exploration of Activities, Reasons, and Barriers of Using Social Media for Food Allergy Management

Managing food allergies can be overwhelming for affected individuals. Social media (SoMe) may serve as a platform for individuals with food allergies to access and share useful information. This study investigates SoMe use among adults with food allergies. Fifty individuals with food allergies answered a series of open-ended questions related to their SoMe use behaviors. The answers were used to develop an online anonymous survey, which was completed by 319 individuals with food allergies. Results indicate that SoMe users mainly use SoMe to gather updated information about food allergies and hear somebody else’s experiences and advices about food allergies. Lack of privacy, concerns about reliability of the information, and lack of efficiency were barriers to the use of SoMe. Those who were younger, had an allergic reaction in restaurants in the past, and who were newly diagnosed with food allergy were more likely to engage in SoMe use for food allergy related purposes. SoMe administrators may seek strategies to remove barriers and share information from credible resources to benefit those in need of such information

Direct Observation of Long-Term Durability of Superconductivity in YBa2_2Cu3_3O7_7-Ag2_2O Composites

We report direct observation of long-term durability of superconductivity of several YBa$_2$Cu$_3$O$_7$-Ag$_2$O composites that were first prepared and studied almost 14 years ago [J. J. Lin {\it et al}., Jpn. J. Appl. Phys. {\bf 29}, 497 (1990)]. Remeasurements performed recently on both resistances and magnetizations indicate a sharp critical transition temperature at 91 K. We also find that such long-term environmental stability of high-temperature superconductivity can only be achieved in YBa$_2$Cu$_3$O$_7$ with Ag$_2$O addition, but not with pure Ag addition.Comment: to be published in Jpn. J. Appl. Phy