2,592 research outputs found
Baryogenesis at the Electroweak Phase Transition for a SUSY Model with a Gauge Singlet
SUSY models with a gauge singlet easily allow for a strongly first order
electroweak phase transition (EWPT). We discuss the wall profile, in particular
transitional CP violation during the EWPT. We calculate CP violating source
terms for the charginos in the WKB approximation and solve the relevant
transport equations to obtain the generated baryon asymmetry.Comment: 5 pages, 6 figures. To appear in the Proceedings of Strong and
Electroweak Matter 2000 (SEWM2000), Marseilles; a reference adde
Suppressing lepton flavor violation in a soft-wall extra dimension
A soft-wall warped extra dimension allows one to relax the tight constraints imposed by electroweak data in conventional Randall-Sundrum models. We investigate a setup, where the lepton flavor structure of the standard model is realized by split fermion locations. Bulk fermions with general locations are not analytically tractable in a soft-wall background, so we follow a numerical approach to perform the Kaluza-Klein reduction. Lepton flavor violation is induced by the exchange of Kaluza-Klein gauge bosons. We find that rates for processes such as muon-electron conversion are significantly reduced compared to hard-wall models, allowing for a Kaluza-Klein scale as low as 2 TeV. Accommodating small neutrino masses forces one to introduce a large hierarchy of scales into the model, making pressing the question of a suitable stabilization mechanism
New Estimates of State and Local Government Tangible Capital and Net Investment
Measures of the state and local government capital stock and investment are necessary inputs into several areas of economic analysis, including the measurement of national wealth and its growth. We estimate net investment and depreciation of state and local government nonresidential capital. In aggregate, we estimate a net state and local nonresidential capital stock of $1.8 trillion in 1985, 17% larger than that estimated by the Bureau of Economic Analysis. Net state and local government investment has exceeded the state and local deficit annually for the last forty-five years. While the fraction of state and local purchase of goods and services devoted to net investment has fallen, it has exceeded federal government net capital formation except during defense buildups and has averaged more than 40% of private fixed nonresidential net investment since 1951. Similar comparisons reveal that the state and local government net capital stock substantially exceeds state and local debt, and is about twice the federal government capital stock.
SWEEPFINDER2: Increased sensitivity, robustness, and flexibility
SweepFinder is a popular program that implements a powerful likelihood-based
method for detecting recent positive selection, or selective sweeps. Here, we
present SweepFinder2, an extension of SweepFinder with increased sensitivity
and robustness to the confounding effects of mutation rate variation and
background selection, as well as increased flexibility that enables the user to
examine genomic regions in greater detail and to specify a fixed distance
between test sites. Moreover, SweepFinder2 enables the use of invariant sites
for sweep detection, increasing both its power and precision relative to
SweepFinder
Gravity Waves from a Cosmological Phase Transition: Gauge Artifacts and Daisy Resummations
The finite-temperature effective potential customarily employed to describe
the physics of cosmological phase transitions often relies on specific gauge
choices, and is manifestly not gauge-invariant at finite order in its
perturbative expansion. As a result, quantities relevant for the calculation of
the spectrum of stochastic gravity waves resulting from bubble collisions in
first-order phase transitions are also not gauge-invariant. We assess the
quantitative impact of this gauge-dependence on key quantities entering
predictions for gravity waves from first order cosmological phase transitions.
We resort to a simple abelian Higgs model, and discuss the case of R_xi gauges.
By comparing with results obtained using a gauge-invariant Hamiltonian
formalism, we show that the choice of gauge can have a dramatic effect on
theoretical predictions for the normalization and shape of the expected gravity
wave spectrum. We also analyze the impact of resumming higher-order
contributions as needed to maintain the validity of the perturbative expansion,
and show that doing so can suppress the amplitude of the spectrum by an order
of magnitude or more. We comment on open issues and possible strategies for
carrying out "daisy resummed" gauge invariant computations in non-Abelian
models for which a gauge-invariant Hamiltonian formalism is not presently
available.Comment: 25 pages, 10 figure
Block-Transitive Designs in Affine Spaces
This paper deals with block-transitive - designs in affine
spaces for large , with a focus on the important index case. We
prove that there are no non-trivial 5- designs admitting a
block-transitive group of automorphisms that is of affine type. Moreover, we
show that the corresponding non-existence result holds for 4- designs,
except possibly when the group is one-dimensional affine. Our approach involves
a consideration of the finite 2-homogeneous affine permutation groups.Comment: 10 pages; to appear in: "Designs, Codes and Cryptography
A Tachyonic Gluon Mass: Between Infrared and Ultraviolet
The gluon spin coupling to a Gaussian correlated background gauge field
induces an effective tachyonic gluon mass. It is momentum dependent and
vanishes in the UV only like 1/p^2. In the IR, we obtain stabilization through
a positive m^2_{conf}(p^2) related to confinement. Recently a purely
phenomenological tachyonic gluon mass was used to explain the linear rise in
the q\bar q static potential at small distances and also some long standing
discrepancies found in QCD sum rules. We show that the stochastic vacuum model
of QCD predicts a gluon mass with the desired properties.Comment: 10 pages LaTeX, 2 figures using eps
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Loss of Cln3 Function in the Social Amoeba Dictyostelium discoideum Causes Pleiotropic Effects That Are Rescued by Human CLN3
The neuronal ceroid lipofuscinoses (NCL) are a group of inherited, severe neurodegenerative disorders also known as Batten disease. Juvenile NCL (JNCL) is caused by recessive loss-of-function mutations in CLN3, which encodes a transmembrane protein that regulates endocytic pathway trafficking, though its primary function is not yet known. The social amoeba Dictyostelium discoideum is increasingly utilized for neurological disease research and is particularly suited for investigation of protein function in trafficking. Therefore, here we establish new overexpression and knockout Dictyostelium cell lines for JNCL research. Dictyostelium Cln3 fused to GFP localized to the contractile vacuole system and to compartments of the endocytic pathway. cln3− cells displayed increased rates of proliferation and an associated reduction in the extracellular levels and cleavage of the autocrine proliferation repressor, AprA. Mid- and late development of cln3− cells was precocious and cln3− slugs displayed increased migration. Expression of either Dictyostelium Cln3 or human CLN3 in cln3− cells suppressed the precocious development and aberrant slug migration, which were also suppressed by calcium chelation. Taken together, our results show that Cln3 is a pleiotropic protein that negatively regulates proliferation and development in Dictyostelium. This new model system, which allows for the study of Cln3 function in both single cells and a multicellular organism, together with the observation that expression of human CLN3 restores abnormalities in Dictyostelium cln3− cells, strongly supports the use of this new model for JNCL research
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