669 research outputs found
Adjoint fermion zero-modes for SU(N) calorons
We derive analytic formulas for the zero-modes of the Dirac equation in the
adjoint representation in the background field of Q=1 SU(N) calorons. Solutions
with various boundary conditions are obtained, including the physically most
relevant cases of periodic and antiperiodic ones. The latter are essential
ingredients in a semiclassical treatment of finite temperature supersymmetric
Yang-Mills theory. A detailed discussion of adjoint zero-modes in several other
contexts is also presented.Comment: 40 latex pages and 5 eps figure
Probing for Instanton Quarks with epsilon-Cooling
We use epsilon-cooling, adjusting at will the order a^2 corrections to the
lattice action, to study the parameter space of instantons in the background of
non-trivial holonomy and to determine the presence and nature of constituents
with fractional topological charge at finite and zero temperature for SU(2). As
an additional tool, zero temperature configurations were generated from those
at finite temperature with well-separated constituents. This is achieved by
"adiabatically" adjusting the anisotropic coupling used to implement finite
temperature on a symmetric lattice. The action and topological charge density,
as well as the Polyakov loop and chiral zero-modes are used to analyse these
configurations. We also show how cooling histories themselves can reveal the
presence of constituents with fractional topological charge. We comment on the
interpretation of recent fermion zero-mode studies for thermalized ensembles at
small temperatures.Comment: 26 pages, 14 figures in 33 part
Eosinofilia en sala de clĂnica mĂ©dica
La eosinofilia en sangre perifĂ©rica es un trastorno frecuente en nuestro medio. Las causas son numerosas y dentro de ellas se encuentran las infecciones parasitarias, atopia, reacciones adversas a drogas y neoplasias tanto de Ăłrganos sĂłlidos como hematolĂłgicas. El objetivo de este estudio es determinar las etiologĂas mĂĄs frecuentes de eosinofilia en pacientes que ingresaron o cursaron internaciĂłn en sala de clĂnica mĂ©dica en el Ășltimo año.Facultad de Ciencias MĂ©dica
Symmetry Breaking and False Vacuum Decay after Hybrid Inflation
We discuss the onset of symmetry breaking from the false vacuum in generic
scenarios in which the mass squared of the symmetry breaking (Higgs) field
depends linearly with time, as it occurs, via the evolution of the inflaton, in
models of hybrid inflation. We show that the Higgs fluctuations evolve from
quantum to classical during the initial stages. This justifies the subsequent
use of real-time lattice simulations to describe the fully non-perturbative and
non-linear process of symmetry breaking. The early distribution of the Higgs
field is that of a smooth classical gaussian random field, and consists of
lumps whose shape and distribution is well understood analytically. The lumps
grow with time and develop into ``bubbles'' which eventually collide among
themselves, thus populating the high momentum modes, in their way towards
thermalization at the true vacuum. With the help of some approximations we are
able to provide a quasi-analytic understanding of this process.Comment: 33 pages, 16 figures, LaTeX, uses revtex. Version to be published in
Phys. Rev. with minor change
The gradient flow running coupling with twisted boundary conditions
We study the gradient flow for Yang-Mills theories with twisted boundary
conditions. The perturbative behavior of the energy density is used to define a running coupling at a scale given by the
linear size of the finite volume box. We compute the non-perturbative running
of the pure gauge coupling constant and conclude that the technique is
well suited for further applications due to the relatively mild cutoff effects
of the step scaling function and the high numerical precision that can be
achieved in lattice simulations. We also comment on the inclusion of matter
fields.Comment: 27 pages. LaTe
miR-146a rs2431697 identifies myeloproliferative neoplasm patients with higher secondary myelofibrosis progression risk
Myelofibrosis (MF) occurs as part of the natural history of polycythemia vera (PV) and essential thrombocythemia (ET), and remarkably shortens survival. Although JAK2V617F and CALR allele burden are the main transformation risk factors, inflammation plays a critical role by driving clonal expansion toward end-stage disease. NF-ÎșB is a key mediator of inflammation-induced carcinogenesis. Here, we explored the involvement of miR-146a, a brake in NF-ÎșB signaling, in MPN susceptibility and progression. rs2910164 and rs2431697, that affect miR-146a expression, were analyzed in 967 MPN (320 PV/333 ET/314 MF) patients and 600 controls. We found that rs2431697 TT genotype was associated with MF, particularly with post-PV/ET MF (HRâ=â1.5; pâ<â0.05). Among 232 PV/ET patients (follow-up time=8.5 years), 18 (7.8%) progressed to MF, being MF-free-survival shorter for rs2431697 TT than CCâ+âCT patients (pâ=â0.01). Multivariate analysis identified TT genotype as independent predictor of MF progression. In addition, TT (vs. CCâ+âCT) patients showed increased plasma inflammatory cytokines. Finally, miR-146aâ/â mice showed significantly higher Stat3 activity with aging, parallel to the development of the MF-like phenotype. In conclusion, we demonstrated that rs2431697 TT genotype is an early predictor of MF progression independent of the JAK2V617F allele burden. Low levels of miR-146a contribute to the MF phenotype by increasing Stat3 signaling
Constraining the Ratio in TeV Cosmic Rays with Observations of the Moon Shadow by HAWC
An indirect measurement of the antiproton flux in cosmic rays is possible as
the particles undergo deflection by the geomagnetic field. This effect can be
measured by studying the deficit in the flux, or shadow, created by the Moon as
it absorbs cosmic rays that are headed towards the Earth. The shadow is
displaced from the actual position of the Moon due to geomagnetic deflection,
which is a function of the energy and charge of the cosmic rays. The
displacement provides a natural tool for momentum/charge discrimination that
can be used to study the composition of cosmic rays. Using 33 months of data
comprising more than 80 billion cosmic rays measured by the High Altitude Water
Cherenkov (HAWC) observatory, we have analyzed the Moon shadow to search for
TeV antiprotons in cosmic rays. We present our first upper limits on the
fraction, which in the absence of any direct measurements, provide
the tightest available constraints of on the antiproton fraction for
energies between 1 and 10 TeV.Comment: 10 pages, 5 figures. Accepted by Physical Review
Very high energy particle acceleration powered by the jets of the microquasar SS 433
SS 433 is a binary system containing a supergiant star that is overflowing
its Roche lobe with matter accreting onto a compact object (either a black hole
or neutron star). Two jets of ionized matter with a bulk velocity of
extend from the binary, perpendicular to the line of sight, and
terminate inside W50, a supernova remnant that is being distorted by the jets.
SS 433 differs from other microquasars in that the accretion is believed to be
super-Eddington, and the luminosity of the system is erg
s. The lobes of W50 in which the jets terminate, about 40 pc from the
central source, are expected to accelerate charged particles, and indeed radio
and X-ray emission consistent with electron synchrotron emission in a magnetic
field have been observed. At higher energies (>100 GeV), the particle fluxes of
rays from X-ray hotspots around SS 433 have been reported as flux
upper limits. In this energy regime, it has been unclear whether the emission
is dominated by electrons that are interacting with photons from the cosmic
microwave background through inverse-Compton scattering or by protons
interacting with the ambient gas. Here we report TeV -ray observations
of the SS 433/W50 system where the lobes are spatially resolved. The TeV
emission is localized to structures in the lobes, far from the center of the
system where the jets are formed. We have measured photon energies of at least
25 TeV, and these are certainly not Doppler boosted, because of the viewing
geometry. We conclude that the emission from radio to TeV energies is
consistent with a single population of electrons with energies extending to at
least hundreds of TeV in a magnetic field of ~micro-Gauss.Comment: Preprint version of Nature paper. Contacts: S. BenZvi, B. Dingus, K.
Fang, C.D. Rho , H. Zhang, H. Zho
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