2,843 research outputs found
Measurement of helium-3 and deuterium stopping power ratio for negative muons
The measurement method and results measuring of the stopping power ratio of
helium-3 and deuterium atoms for muons slowed down in the D/He mixture are
presented. Measurements were performed at four values of pure He gas target
densities, (normalized to the
liquid hydrogen density) and at a density 0.0585 of the D/He mixture. The
experiment was carried out at PSI muon beam E4 with the momentum P MeV/c. The measured value of the mean stopping ratio is
. This value can also be interpreted as the value of mean reduced
ratio of probabilities for muon capture by helium-3 and deuterium atoms.Comment: 7 pages, 6 figure
Dispersion relations and subtractions in hard exclusive processes
We study analytical properties of the hard exclusive processes amplitudes. We
found that QCD factorization for deeply virtual Compton scattering and hard
exclusive vector meson production results in the subtracted dispersion relation
with the subtraction constant determined by the Polyakov-Weiss -term. The
relation of this constant to the fixed pole contribution found by Brodsky,
Close and Gunion and defined by parton distributions is proved, while its
manifestation is spoiled by the small divergence. The continuation to the
real photons limit is considered and the numerical correspondence between
lattice simulations of -term and low energy Thomson amplitude is found.Comment: 4 pages, journal versio
The role of impacting processes in the chemical evolution of the atmosphere of primordial Earth
The role of impacting processes in the chemical evolution of the atmosphere of primordial Earth is discussed. The following subject areas are covered: (1) Earth's initial atmosphere; (2) continuous degassing; (3) impact processes and the Earth's protoatmosphere; and (4) the evolution of an impact-generated atmosphere
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