4,970 research outputs found
Staggered chiral random matrix theory
We present a random matrix theory (RMT) for the staggered lattice QCD Dirac
operator. The staggered RMT is equivalent to the zero-momentum limit of the
staggered chiral Lagrangian and includes all taste breaking terms at their
leading order. This is an extension of previous work which only included some
of the taste breaking terms. We will also present some results for the taste
breaking contributions to the partition function and the Dirac eigenvalues.Comment: 12 pages, 7 figures, v2 has minor edits and corrections to some
equations to match published versio
Fetal and early neonatal interleukin-6 response
In 1998, a systemic fetal cytokine response, defined as a plasma interleukin-6 (IL-6) value above 11 pg/mL, was reported to be a major independent risk factor for the subsequent development of neonatal morbid events even after adjustments for gestational age and other confounders. Since then, the body of literature investigating the use of blood concentrations of IL-6 as a hallmark of the fetal inflammatory response syndrome (FIRS), a diagnostic marker of early-onset neonatal sepsis (EONS) and a risk predictor of white matter injury (WMI), has grown rapidly. In this article, we critically review: IL-6 biological functions; current evidence on the association between IL-6, preterm birth, FIRS and EONS; IL-6 reference intervals and dynamics in the early neonatal period; IL-6 response during the immediate postnatal period and perinatal confounders; accuracy and completeness of IL-6 diagnostic studies for EONS (according to the Standards for Reporting of Diagnostic Accuracy statement); and recent breakthroughs in the association between fetal blood IL-6, EONS, and WMI
Optical Production of Stable Ultracold Sr Molecules
We have produced large samples of ultracold Sr molecules in the
electronic ground state in an optical lattice. The molecules are bound by 0.05
cm and are stable for several milliseconds. The fast, all-optical method
of molecule creation via intercombination line photoassociation relies on a
near-unity Franck-Condon factor. The detection uses a weakly bound vibrational
level corresponding to a very large dimer. This is the first of two steps
needed to create Sr in the absolute ground quantum state. Lattice-trapped
Sr is of interest to frequency metrology and ultracold chemistry.Comment: 5 pages, 3 figure
The 2+1 flavor topological susceptibility from the asqtad action at 0.06 fm
We report new data for the topological susceptibility computed on 2+1 flavor
dynamical configurations with lattice spacing 0.06 fm, generated with the
asqtad action. The topological susceptibility is computed by HYP smearing and
compared with rooted staggered chiral perturbation theory as the pion mass goes
to zero. At 0.06 fm, the raw data is already quite close to the continuum
extrapolated values obtained from coarser lattices. These results provide a
further test of the asqtad action with rooted staggered flavors.Comment: 7 pages, 5 figures, talk presented at the XXV International Symposium
on Lattice Field Theory, July 30 - August 4, 2007, Regensburg, German
Microscopic eigenvalue correlations in QCD with imaginary isospin chemical potential
We consider the chiral limit of QCD subjected to an imaginary isospin
chemical potential. In the epsilon-regime of the theory we can perform precise
analytical calculations based on the zero-momentum Goldstone modes in the
low-energy effective theory. We present results for the spectral correlation
functions of the associated Dirac operators.Comment: 13 pages, 2 figures, RevTe
Decoupling a Cooper-pair box to enhance the lifetime to 0.2 ms
We present a circuit QED experiment in which a separate transmission line is
used to address a quasi-lumped element superconducting microwave resonator
which is in turn coupled to an Al/AlO/Al Cooper-pair box (CPB) charge
qubit. In our measurements we find a strong correlation between the measured
lifetime of the CPB and the coupling between the qubit and the transmission
line. By monitoring perturbations of the resonator's 5.44 GHz resonant
frequency, we have measured the spectrum, lifetime (), Rabi, and Ramsey
oscillations of the CPB at the charge degeneracy point while the CPB was
detuned by up to 2.5 GHz . We find a maximum lifetime of the CPB was s for to 4.5 GHz. Our measured 's are consistent with
loss due to coupling to the transmission line, spurious microwave circuit
resonances, and a background decay rate on the order of
s of unknown origin, implying that the loss tangent in the AlO
junction barrier must be less than about at 4.5 GHz, about 4
orders of magnitude less than reported in larger area Al/AlO/Al tunnel
junctions
Stochastic field theory for a Dirac particle propagating in gauge field disorder
Recent theoretical and numerical developments show analogies between quantum
chromodynamics (QCD) and disordered systems in condensed matter physics. We
study the spectral fluctuations of a Dirac particle propagating in a finite
four dimensional box in the presence of gauge fields. We construct a model
which combines Efetov's approach to disordered systems with the principles of
chiral symmetry and QCD. To this end, the gauge fields are replaced with a
stochastic white noise potential, the gauge field disorder. Effective
supersymmetric non-linear sigma-models are obtained. Spontaneous breaking of
supersymmetry is found. We rigorously derive the equivalent of the Thouless
energy in QCD. Connections to other low-energy effective theories, in
particular the Nambu-Jona-Lasinio model and chiral perturbation theory, are
found.Comment: 4 pages, 1 figur
Baryon masses with improved staggered quarks
The MILC collaboration's simulations with improved staggered quarks are being
extended with runs at a lattice spacing of 0.06 fm with quark masses down to
one tenth the strange quark mass. We give a brief introduction to these new
simulations and the determination of the lattice spacing. Then we combine these
new runs with older results to study the masses of the nucleon and the Omega
minus in the continuum and chiral limits.Comment: 7 pages, proceedings from Lattice 2007 conferenc
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