The spin density matrix of top quark pairs produced in electron-positron annihilation including QCD radiative corrections

We calculate the spin density matrix of top quark pairs for the reaction $e^+e^-\to t\bar{t}X$ to order $\alpha_s$. As an application we show next-to-leading order results for a variety of spin observables for the $t\bar{t}$ system. These include the top quark and antiquark polarizations and $t\bar{t}$ spin-spin correlations as a function of the center-of-mass energy and of the top quark scattering angle for arbitrary longitudinal polarization of the electron/positron beam.Comment: 26 pages, 13 Postscript figures, uses REVTE

Polarization and spin correlations of top quarks at a future e+ e- linear collider

We discuss the polarization and spin correlations of top quarks produced above threshold at a future linear collider, including QCD radiative corrections.Comment: 11 pages (LaTeX), 16 Postscript figure. Contribution to the International Workshop on "Symmetry and Spin", PRAHA-SPIN99, Prague, Czech Republic, September 5 -12, 199

Effects of Higgs sector CP violation in top-quark pair production at the LHC

A striking manifestation of CP violation in the electroweak symmetry breaking sector would be the existence of neutral Higgs boson(s) with undefined CP parity. We analyse signatures of such a boson, with a mass of about 300 GeV or larger, produced in high energy proton-proton collisions at LHC energies in its top-quark antitop-quark decay channel. The large irreducible $t\bar t$ background is taken into account. We propose, both for the dilepton and the lepton + jets decay channels of $t\bar t$, several correlations and asymmetries with which (Higgs sector) CP violation can be traced. We show that for judiciously chosen cuts on the $t\bar t$ invariant mass these CP observables yield, for an LHC integrated luminosity of 100 $\rm{fb}^{-1}$, statistically significant signals for a range of Higgs boson masses and Yukawa couplings.Comment: 36 pages, 25 Postscript figure

Exploring local quantum many-body relaxation by atoms in optical superlattices

We establish a setting - atoms in optical superlattices with period 2 - in which one can experimentally probe signatures of the process of local relaxation and apparent thermalization in non-equilibrium dynamics without the need of addressing single sites. This opens up a way to explore the convergence of subsystems to maximum entropy states in quenched quantum many-body systems with present technology. Remarkably, the emergence of thermal states does not follow from a coupling to an environment, but is a result of the complex non-equilibrium dynamics in closed systems. We explore ways of measuring the relevant signatures of thermalization in this analogue quantum simulation of a relaxation process, exploiting the possibilities offered by optical superlattices.Comment: 4 pages, 3 figures, version to published in Physical Review Letter

Population Trends of Bighorn Sheep and Mountain Goats in the Greater Yellowstone Area

Bighorn sheep (Ovis canadensis) and mountain goats (Oreamnos americanus) are important components of the large mammal community in the Greater Yellowstone Area (GYA) and are of considerable public interest. However, foundational ecological research concerning these species is limited. We analyzed historic bighorn sheep and mountain goat population counts collected by management biologists using ln-linear regression to estimate herd growth rates (?). The analyzed dataset consisted of 538 bighorn sheep counts since 1971 and 120 mountain goat counts since 1966. Most mountain goat count units experienced a positive growth rate and increased their distributions over recent decades. Bighorn sheep growth rates were more variable among the 26 recognized herd units in the GYA. We used the historic count data to evaluate the hypothesis that sympatry of non-native mountain goats with bighorn sheep adversely affected bighorn sheep populations. This was accomplished by comparing the growth rates of sympatric herds with that of allopatric herds. There was no evidence that sympatric herd growth rates were significantly lower than allopatric herd growth rates. We caution, however, that many counts in consecutive years suggested larger changes in abundance than what would be reasonable to expect from biological processes. We suspect that variability in counts likely reflects varying detection probability and the overall difficulty of counting mountain ungulates. Therefore, conclusions derived from these data should be further evaluated with more detailed demographic studies in the future

QCD Corrections to Decay Distributions of Neutral Higgs Bosons with (In)definite CP Parity

We compute the order $\alpha_s$ QCD corrections to the density matrix for the decay of a neutral Higgs boson $\phi$ with (in)definite CP parity into a quark antiquark pair, respectively the QED corrections for the decay into a pair of charged leptons. We classify and calculate single spin asymmetries and spin-spin correlations which are generated by the scalar and pseudoscalar Yukawa couplings. These spin effects can be traced in $\phi \to \tau^-\tau^+$ and, for heavy Higgs bosons, in $\phi \to t\bar{t}$. We also calculate resulting correlations among the final states and estimate, for the respective decay modes, the number of events needed to measure the Yukawa couplings with these correlations at the 3 sigma level.Comment: 32 pages, REVTeX, uses: psfig,amssym,aps,preprint 14 ps figure

Bighorn Sheep Movements and Mineral Lick Use in Waterton-Glacier International Peace Park (Poster)

This study used bighorn sheep telemetry data collected in Glacier National Park, Waterton Lakes National Park, and the Blackfeet Reservation to examine bighorn sheep movements and use of known mineral licks.  Over 168,400 GPS locations were collected between 2002 and 2011 on 97 bighorn sheep individuals from 17 different social groups.  We examined the proximity of bighorn sheep telemetry data to 32 known mineral lick locations to describe timing and frequency of mineral lick use.  Fifty individuals had locations near known mineral licks, and most mineral lick visits took place between May and August.  We compared movements towards known mineral lick locations with general bighorn sheep movements.  After estimating bighorn sheep kernel home ranges, we evaluated how movement towards the lick, timing, and frequency of use varied depending on location of the lick relative to sheep home ranges.  We conducted a k-means cluster analysis of movement characteristics to identify potential locations of unknown mineral licks and movement pinch points.  We will discuss options for using these locations to monitor bighorn sheep health and population size

An intact signal peptide on dengue virus E protein enhances immunogenicity for CD8+ T cells and antibody when expressed from modified vaccinia Ankara

Dengue is a global public health concern and this is aggravated by a lack of vaccines or antiviral therapies. Despite the well-known role of CD8(+) T cells in the immunopathogenesis of Dengue virus (DENV), only recent studies have highlighted the importance of this arm of the immune response in protection against the disease. Thus, the majority of DENV vaccine candidates are designed to achieve protective titers of neutralizing antibodies, with less regard for cellular responses. Here, we used a mouse model to investigate CD8(+) T cell and humoral responses to a set of potential DENV vaccines based on recombinant modified vaccinia virus Ankara (rMVA). To enable this study, we identified two CD8(+) T cell epitopes in the DENV-3 E protein in C57BL/6 mice. Using these we found that all the rMVA vaccines elicited DENV-specific CD8(+) T cells that were cytotoxic in vivo and polyfunctional in vitro. Moreover, vaccines expressing the E protein with an intact signal peptide sequence elicited more DENV-specific CD8(+) T cells than those expressing E proteins in the cytoplasm. Significantly, it was these same ER-targeted E protein vaccines that elicited antibody responses. Our results support the further development of rMVA vaccines expressing DENV E proteins and add to the tools available for dengue vaccine development.Parts of this work were supported by the InstitutoNacional de Ciência e Tecnologia de Vacinas–INCTV (National Insti-tute of Science and Technology of Vaccines) and by a FAPEMIGPPM grant (CBB, PPM-00461-11). BRQ was a CAPES/PDSE fellow-ship recipient (8815-11-9). FGF is a CNPq fellowship recipient. DCTis an ARC Future Fellow (FT110100310)