Search results for "external field"
showing 5 items of 15 documents
One-Loop Effective Lagrangian in QED
2020
Our main goal in this section is the derivation of an expression for the effective Lagrangian in one-loop approximation. So let’s start with the vacuum persistence amplitude in presence of an external field: $$\displaystyle \langle 0_+\vert 0_-\rangle ^A = e^{ iW^{(1)}[A]} = e^{i \int d^4x\mathcal {L}^{(1)}(x)} $$
Elastic properties of DNA linked flexible magnetic filaments.
2011
Elastic properties of magnetic filaments linked by DNA in solutions of univalent and bivalent salts with different pH values are investigated through their deformation in an external field. A strong dependence of the bending modulus in bivalent salt solution on the pH is shown. Experimental results are interpreted on the basis of the magnetic elastica.
Improved determination of the mass of the1−+light hybrid meson from QCD sum rules
2003
We calculate the next-to-leading order (NLO) ${\ensuremath{\alpha}}_{s}$ corrections to the contributions of the condensates $〈\ensuremath{\alpha}{G}^{2}〉$ and $〈\overline{q}q{〉}^{2}$ in the current-current correlator of the hybrid current $g\overline{q}(x){\ensuremath{\gamma}}_{\ensuremath{\nu}}{\mathrm{iF}}_{\ensuremath{\mu}\ensuremath{\nu}}^{a}{T}^{a}q(x)$ using the external field method in the Feynman gauge. After incorporating these NLO contributions into the Laplace sum rules, the mass of the ${J}^{\mathrm{PC}}{=1}^{\ensuremath{-}+}$ light hybrid meson is recalculated using the QCD sum rule approach. We find that the sum rules exhibit enhanced stability when the NLO ${\ensuremath{\alp…
Effects of low frequency electric fields on synaptic integration in hippocampal CA1 pyramidal neurons: implications for power line emissions
2014
The possible cognitive effects of low frequency external electric fields, such as those generated by power lines, are poorly understood. Their functional consequences for mechanisms at the single neuron level are very difficult to study and identify experimentally, especially in vivo. The major open problem is that experimental investigations on humans have given inconsistent or contradictory results, making it difficult to estimate the possible effects of external low frequency electric fields on cognitive functions. Here we investigate this issue with a realistic model of hippocampal CA1 pyramidal neurons. The model suggests how and why external electric fields, with environmentally obser…
Optically pumped Cs magnetometers enabling a high-sensitivity search for the neutron electric dipole moment
2020
An array of 16 laser-pumped scalar Cs magnetometers was part of the neutron electric dipole moment (nEDM) experiment taking data at the Paul Scherrer Institute in 2015 and 2016. It was deployed to measure the gradients of the experiment's magnetic field and to monitor their temporal evolution. The originality of the array lies in its compact design, in which a single near-infrared diode laser drives all magnetometers that are located in a high-vacuum chamber, with a selection of the sensors mounted on a high-voltage electrode. We describe details of the Cs sensors' construction and modes of operation, emphasizing the accuracy and sensitivity of the magnetic-field readout. We present two app…