138 research outputs found
Evaluating chiral symmetry restoration through the use of sum rules
We pursue the idea of assessing chiral restoration via in-medium
modifications of hadronic spectral functions of chiral partners. The usefulness
of sum rules in this endeavor is illustrated, focusing on the vector and
axial-vector channels. We first present an update on constructing quantitative
results for pertinent vacuum spectral functions. These spectral functions serve
as a basis upon which the in-medium spectral functions can be constructed. A
striking feature of our analysis of the vacuum spectral functions is the need
to include excited resonances, dictated by satisfying the Weinberg-type sum
rules. This includes excited states in both the vector and axial-vector
channels. Preliminary results for the finite temperature vector spectral
function are presented. Based on a rho spectral function tested in dilepton
data which develops a shoulder at low energies, we find that the rho' peak
flattens off. The flattening may be a sign of chiral restoration, though a
study of the finite temperature axial-vector spectral function remains to be
carried out.Comment: 9 pages, conference proceedings from Resonance Workshop at UT Austin,
March 5-7 201
Dielectron Measurements in STAR
Ultrarelativistic heavy-ion collisions provide a unique environment to study
the properties of strongly interacting matter. Dileptons, which are not
affected by the strong interactions, are an ideal penetrating probe. We present
the dielectron results for p+p and Au+Au collisions at \sqrt{s_\mathrm{NN}}}
=200 GeV, as measured by the STAR experiment. We discuss the prospects of
dilepton measurements with the near-future detector upgrades, and the recent
lower beam energy Au+Au measurements.Comment: Resonance Workshop at UT Austin (2012), 8 pages,15 figure
Resonances and fluctuations in the statistical model
We describe how the study of resonances and fluctuations can help constrain
the thermal and chemical freezeout properties of the fireball created in heavy
ion collisions. This review is based on [1-5].Comment: Proceedings,"Hadronic resonance production in heavy ion and
elementary collisions" UT Austin, March 5-7 201
Emergence of Skyrme crystal in Gross-Neveu and 't Hooft models at finite density
We study two-dimensional, large field theoretic models (Gross-Neveu
model, 't Hooft model) at finite baryon density near the chiral limit. The same
mechanism which leads to massless baryons in these models induces a breakdown
of translational invariance at any finite density. In the chiral limit baryonic
matter is characterized by a spatially varying chiral angle with a wave number
depending only on the density. For small bare quark masses a sine-Gordon kink
chain is obtained which may be regarded as simplest realization of the Skyrme
crystal for nuclear matter. Characteristic differences between confining and
non-confining models are pointed out.Comment: 27 pages, 11 figures, added reference, corrected sig
Neutrino Cooling of Neutron Stars. Medium effects
This review demonstrates that neutrino emission from dense hadronic component
in neutron stars is subject of strong modifications due to collective effects
in the nuclear matter. With the most important in-medium processes incorporated
in the cooling code an overall agreement with available soft X ray data can be
easily achieved. With these findings so called "standard" and "non-standard"
cooling scenarios are replaced by one general "nuclear medium cooling scenario"
which relates slow and rapid neutron star coolings to the star masses (interior
densities). In-medium effects take important part also at early hot stage of
neutron star evolution decreasing the neutrino opacity for less massive and
increasing for more massive neutron stars. A formalism for calculation of
neutrino radiation from nuclear matter is presented that treats on equal
footing one-nucleon and multiple-nucleon processes as well as reactions with
resonance bosons and condensates. Cooling history of neutron stars with quark
cores is also discussed.Comment: To be published in "Physics of Neutron Star Interiors", Eds. D.
Blaschke, N.K. Glendenning, A. Sedrakian, Springer, Heidelberg (2001
Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET
The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR
Relationship of edge localized mode burst times with divertor flux loop signal phase in JET
A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM
New filovirus disease classification and nomenclature
Filoviruses, the members of the family Filoviridae, are
currently classified into one proposed and five established
genera (Supplementary Table 1). Of the twelve
described filoviruses, six have been identified as aetiological
agents of naturally occurring human disease
outbreaks
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