The stransverse mass, MT2, in special cases

This document describes some special cases in which the stransverse mass, MT2, may be calculated by non-iterative algorithms. The most notable special case is that in which the visible particles and the hypothesised invisible particles are massless -- a situation relevant to its current usage in the Large Hadron Collider as a discovery variable, and a situation for which no analytic answer was previously known. We also derive an expression for MT2 in another set of new (though arguably less interesting) special cases in which the missing transverse momentum must point parallel or anti parallel to the visible momentum sum. In addition, we find new derivations for already known MT2 solutions in a manner that maintains manifest contralinear boost invariance throughout, providing new insights into old results. Along the way, we stumble across some unexpected results and make conjectures relating to geometric forms of M_eff and H_T and their relationship to MT2.Comment: 11 pages, no figures. v2 corrects minor typos. v3 corrects an incorrect statement in footnote 8 and inserts a missing term in eq (3.9). v4 and v5 correct minor typos spotted by reader

Higgs-Mediated tau -> 3 mu in the Supersymmetric Seesaw Model

Recent observations of neutrino oscillations imply non-zero neutrino masses and flavor violation in the lepton sector, most economically explained by the seesaw mechanism. Within the context of supersymmetry, lepton flavor violation (LFV) among the neutrinos can be communicated by renormalization group flow to the sleptons and from there to the charged leptons. We show that LFV can appear in the couplings of the neutral Higgs bosons, an effect that is strongly enhanced at large tan(beta). In particular, we calculate the branching fraction for tau -> 3 mu and mu -> 3 e mediated by Higgs and find that they can be as large as 10^{-7} and 5x10^{-14} respectively. These modes, along with B^0 -> mu mu, can provide important evidence for supersymmetry before direct discovery of supersymmetric partners occurs. Along with tau -> mu gamma and mu -> e gamma, they can also provide key insights into the form of the neutrino Yukawa mass matrix.Comment: 9 pages LaTeX, 2 figures. Added a discussion of mu -> 3e and its ramifications for probing neutrino mass matrix. Also added references, fixed typos, and made one notational chang

The Ingram Vessel 38CT204: Intensive Survey & Excavation of an Upland Rivercraft at Cheraw, South Carolina

In 1993 and 1994 the Underwater Archaeology Division of the South Carolina Institute of Archaeology and Anthropology conducted an intensive survey of the remains of a small, wooden hulled craft in the Great Pee Dee River near Cheraw, South Carolina. The project was sponsored in part by the Cheraw Historical Society and partially funded by a grant from the South Carolina Humanities Council. The Ingram Vessel (38CT204), named after its discoverer Miller Ingram, lay overturned and largely buried beneath the river sediments and protected by a large mushroom-shaped rock just upstream of the site. The site was partially excavated and the hull remains mapped in situ. The investigation revealed a shallow draught, keeled vessel, built entirely of Southern Yellow Pine. The site is tentatively dated to the late 18th-early 19th century. Overall dimensions are estimated to have been approximately 15.5m (50ft, l0 in) in length, with a maximum beam of 4.6m (15ft, lin). This report details the research on the site and places the vessel within a regional maritime historical context. The vessel is, to date, the only ship-built hull excavated in an uplands context near the head of navigation of a South Carolina river.https://scholarcommons.sc.edu/archanth_books/1198/thumbnail.jp

Elevated immune gene expression is associated with poor reproductive success of urban blue tits

Urban and forest habitats differ in many aspects that can lead to modifications of the immune system of wild animals. Altered parasite communities, pollution, and artificial light at night in cities have been associated with exacerbated inflammatory responses, with possibly negative fitness consequences, but few data are available from free-living animals. Here, we investigate how urbanization affects major immune pathways and experimentally test potentially contributing factors in blue tits (Cyanistes caeruleus) from an urban and forest site. We first compared breeding adults by quantifying the mRNA transcript levels of proteins associated with anti-bacterial, anti-malarial (TLR4, LY86) and anti-helminthic (Type 2 transcription factor GATA3) immune responses. Adult urban and forest blue tits differed in gene expression, with significantly increased TLR4 and GATA3, but not LY86, in the city. We then experimentally tested whether these differences were environmentally induced by cross-fostering eggs between the sites and measuring mRNA transcripts in nestlings. The populations differed in reduced reproductive success, with a lower fledging success and lower fledgling weight recorded at the urban site. This mirrors the findings of our twin study reporting that the urban site was severely resource limited when compared to the forest. Because of low urban survival, robust gene expression data were only obtained from nestlings reared in the forest. Transcript levels in these nestlings showed no (TLR4, LY86), or weak (GATA3), differences according to their origin from forest or city nests, suggesting little genetic or maternal contribution to nestling immune transcript levels. Lastly, to investigate differences in parasite pressure between urban and forest sites, we measured the prevalence of malaria in adult and nestling blood. Prevalence was invariably high across environments and not associated with the transcript levels of the studied immune genes. Our results support the hypothesis that inflammatory pathways are activated in an urban environment and suggest that these differences are most likely induced by environmental factors

Percolation of Ion-Irradiation-Induced Disorder in Complex Oxide Interfaces

Mastery of order-disorder processes in highly non-equilibrium nanostructured oxides has significant implications for the development of emerging energy technologies. However, we are presently limited in our ability to quantify and harness these processes at high spatial, chemical, and temporal resolution, particularly in extreme environments. Here we describe the percolation of disorder at the model oxide interface LaMnO$_3$ / SrTiO$_3$, which we visualize during in situ ion irradiation in the transmission electron microscope. We observe the formation of a network of disorder during the initial stages of ion irradiation and track the global progression of the system to full disorder. We couple these measurements with detailed structural and chemical probes, examining possible underlying defect mechanisms responsible for this unique percolative behavior.Comment: 32 pages, 14 figure

Age Differences in Recovery After Sport-Related Concussion: A Comparison of High School and Collegiate Athletes

Younger age has been hypothesized to be a risk factor for prolonged recovery after sport-related concussion, yet few studies have directly evaluated age differences in acute recovery