37,816 research outputs found
Color Octet Scalar Bound States at the LHC
One possible extension of the Standard Model scalar sector includes SU(2)_L
doublet scalars that are color octets rather than singlets. We focus on models
in which the couplings to fermions are consistent with the principle of minimal
flavor violation (MFV), in which case these color octet scalars couple most
strongly to the third generation of quarks. When the Yukawa coupling of color
octet scalars to Standard Model fermions is less than unity, these states can
live long enough to bind into color-singlet spin-0 hadrons, which we call
octetonia. In this paper, we consider the phenomenology of octetonia at the
Large Hadron Collider (LHC). Predictions for their production via gluon-gluon
fusion and their two-body decays into Standard Model gauge bosons, Higgs
bosons, and \bar{t}t are presented.Comment: 13 pages, 5 figures, published versio
Reimplanting Previously Infected Device in the Same Patient: A Clever Way to Provide Essential Therapy
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108366/1/pace12457.pd
Deforming tachyon kinks and tachyon potentials
In this paper we investigate deformation of tachyon potentials and tachyon
kink solutions. We consider the deformation of a DBI type action with gauge and
tachyon fields living on D1-brane and D3-brane world-volume. We deform tachyon
potentials to get other consistent tachyon potentials by using properly a
deformation function depending on the gauge field components. Resolutions of
singular tachyon kinks via deformation and applications of deformed tachyon
potentials to scalar cosmology scenario are discussed.Comment: To appear in JHEP, 19 pages, 5 eps figures, minor changes and one
reference adde
Searching for Dust around Hyper Metal-Poor Stars
We examine the mid-infrared fluxes and spectral energy distributions for
metal-poor stars with iron abundances [Fe/H] , as well as two
CEMP-no stars, to eliminate the possibility that their low metallicities are
related to the depletion of elements onto dust grains in the formation of a
debris disk. Six out of seven stars examined here show no mid-IR excess. These
non-detections rule out many types of circumstellar disks, e.g. a warm debris
disk ( K), or debris disks with inner radii AU, such as
those associated with the chemically peculiar post-AGB spectroscopic binaries
and RV Tau variables. However, we cannot rule out cooler debris disks, nor
those with lower flux ratios to their host stars due to, e.g. a smaller disk
mass, a larger inner disk radius, an absence of small grains, or even a
multicomponent structure, as often found with the chemically peculiar Lambda
Bootis stars. The only exception is HE0107-5240, for which a small mid-IR
excess near 10 microns is detected at the 2- level; if the excess is
real and associated with this star, it may indicate the presence of (recent)
dust-gas winnowing or a binary system.Comment: Accepted for publication in Ap
Effect of the bound nucleon form factors on charged-current neutrino-nucleus scattering
We study the effect of bound nucleon form factors on charged-current
neutrino-nucleus scattering. The bound nucleon form factors of the vector and
axial-vector currents are calculated in the quark-meson coupling model. We
compute the inclusive C() cross sections using a
relativistic Fermi gas model with the calculated bound nucleon form factors.
The effect of the bound nucleon form factors for this reaction is a reduction
of 8% for the total cross section, relative to that calculated with the
free nucleon form factors.Comment: Latex, 11 pages, 3 figures, version to appear in Phys. Rev. C (Brief
Report
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Ampk regulates IgD expression but not energy stress with B cell activation.
Ampk is an energy gatekeeper that responds to decreases in ATP by inhibiting energy-consuming anabolic processes and promoting energy-generating catabolic processes. Recently, we showed that Lkb1, an understudied kinase in B lymphocytes and a major upstream kinase for Ampk, had critical and unexpected roles in activating naïve B cells and in germinal center formation. Therefore, we examined whether Lkb1 activities during B cell activation depend on Ampk and report surprising Ampk activation with in vitro B cell stimulation in the absence of energy stress, coupled to rapid biomass accumulation. Despite Ampk activation and a controlling role for Lkb1 in B cell activation, Ampk knockout did not significantly affect B cell activation, differentiation, nutrient dynamics, gene expression, or humoral immune responses. Instead, Ampk loss specifically repressed the transcriptional expression of IgD and its regulator, Zfp318. Results also reveal that early activation of Ampk by phenformin treatment impairs germinal center formation but does not significantly alter antibody responses. Combined, the data show an unexpectedly specific role for Ampk in the regulation of IgD expression during B cell activation
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