1,704 research outputs found
Coulometry and Calorimetry of Electric Double Layer Formation in Porous Electrodes
Coulometric measurements on salt-water-immersed nanoporous carbon electrodes
reveal, at a fixed voltage, a charge decrease with increasing temperature.
During far-out-of-equilibrium charging of these electrodes, calorimetry
indicates the production of both irreversible Joule heat and reversible heat,
the latter being associated with entropy changes during electric double layer
(EDL) formation in the nanopores. These measurements grant experimental access
--for the first time-- to the entropic contribution of the grand potential; for
our electrodes, this amounts to roughly 25% of the total grand potential energy
cost of EDL formation at large applied potentials, in contrast with
point-charge model calculations that predict 100%. The coulometric and
calorimetric experiments show a consistent picture of the role of heat and
temperature in EDL formation and provide hitherto unused information to test
against EDL models.Comment: 11 pages, 10 figure
Proton structure corrections to hyperfine splitting in muonic hydrogen
We present the derivation of the formulas for the proton structure-dependent
terms in the hyperfine splitting of muonic hydrogen. We use compatible
conventions throughout the calculations to derive a consistent set of formulas
that reconcile differences between our results and some specific terms in
earlier work. Convention conversion corrections are explicitly presented, which
reduce the calculated hyperfine splitting by about 46 ppm. We also note that
using only modern fits to the proton elastic form factors gives a smaller than
historical spread of Zemach radii and leads to a reduced uncertainty in the
hyperfine splitting. Additionally, hyperfine splittings have an impact on the
muonic hydrogen Lamb shift/proton radius measurement, however the correction we
advocate has a small effect there.Comment: 6 pages, 3 figure
Higher twist analysis of the proton g_1 structure function
We perform a global analysis of all available spin-dependent proton structure
function data, covering a large range of Q^2, 1 < Q^2 < 30 GeV^2, and calculate
the lowest moment of the g_1 structure function as a function of Q^2. From the
Q^2 dependence of the lowest moment we extract matrix elements of twist-4
operators, and determine the color electric and magnetic polarizabilities of
the proton to be \chi_E = 0.026 +- 0.015 (stat) + 0.021/-0.024 (sys) and \chi_B
= -0.013 -+ 0.007 (stat) - 0.010/+0.012 (sys), respectively.Comment: 6 pages, 2 figures, to appear in Phys. Lett.
Self-Consistent Data Analysis of the Proton Structure Function g1 and Extraction of its Moments
The reanalysis of all available world data on the longitudinal asymmetry A||
is presented. The proton structure function g1 was extracted within a unique
framework of data inputs and assumptions. These data allowed for a reliable
evaluation of moments of the structure function g1 in the Q2 range from 0.2 up
to 30 GeV2. The Q2 evolution of the moments was studied in QCD by means of
Operator Product Expansion (OPE).Comment: Proceeding of 3rd International Symposium on the
Gerasimov-Drell-Hearn Sum Rule and its extensions, Old Dominion University,
Norfolk, Virginia June 2-5, 200
Сучасні глобальні процеси у світовій економіці та їх вплив на економічну безпеку держави
Мета роботи. Визначення особливостей формування системи економічної безпеки держави, взагалі, та
України, зокрема, в сучасних умовах глобального розвитку світового господарства
Spin and parity measurement of the Lambda(1405) baryon
A determination of the spin and parity of the Lambda(1405) is presented using photoproduction data from the CLAS detector at Jefferson Lab. The reaction gamma + p -\u3e K+ + Lambda(1405) is analyzed in the decay channel Lambda(1405) -\u3e Sigma(+) + pi(-), where the decay distribution to Sigma(+)pi(-) the variation of the Sigma(+) polarization with respect to the Lambda(1405) polarization direction determines the parity. The Lambda(1405) is produced, in the energy range 2.55 \u3c W \u3c 2.85 GeV and for 0.6 \u3c cos theta(c.m.)(K+) \u3c 0.9, with polarization P = 0.45 +/- 0.02(stat) +/- 0.07(syst). The analysis shows that the decays are in S wave, with the Sigma(+) polarized such that the Lambda(1405) has spin-parity J(P) = 1(-)/2, as expected by most theories
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