4,967 research outputs found
Realistic calculations of nuclear disappearance lifetimes induced by neutron-antineutron oscillations
Realistic calculations of nuclear disappearance lifetimes induced by
neutron-antineutron oscillations are reported for oxygen and iron, using
antineutron nuclear potentials derived from a recent comprehensive analysis of
antiproton atomic X-ray and radiochemical data. A lower limit of 3.3 x 10E8 s
on the neutron-antineutron oscillation time is derived from the
Super-Kamiokande I new lower limit of 1.77 x 10E32 yr on the neutron lifetime
in oxygen. Antineutron scattering lengths in carbon and nickel, needed in trap
experiments using ultracold neutrons, are calculated from updated antinucleon
optical potentials at threshold, with results shown to be largely model
independent.Comment: version matching PRD publication, typos and references correcte
Extraction of Neutrino Flux with the Low Method at MiniBooNE Energies
We describe the application of the `low-' method to the extraction of
the neutrino flux at MiniBooNE energies. As an example, we extract the relative
energy dependence of the flux from published MiniBooNE quasielastic scattering
cross sections with GeV and GeV (here is the
energy transfer to the target). We find that the flux extracted from the
`low-' cross sections is consistent with the nominal flux used by
MiniBooNE. We fit the MiniBooNE cross sections over the entire kinematic range
to various parametrizations of the axial form factor. We find that if the
overall normalization of the fit is allowed to float within the normalization
errors, the extracted values of the axial vector mass are independent of the
flux. Within the Fermi gas model, the distribution of the MiniBooNE data
is described by a standard dipole form factor with GeV. If
nuclear transverse enhancement in the vector form factors is accounted for, the
data are best fit with a modified dipole form factor with
GeV.Comment: 5 pages, 6 figures, (presented by A. Bodek at CIPANP 2012, St.
Petersburg, FL, June 2012, and at NuFact 2012, Williamsburg, VA, July 2012
A remark on sphaleron erasure of baryon asymmetry
We complete an existing result for how the baryon asymmetry left over after a
period of full thermal equilibrium depends on different lepton asymmetries.Comment: 5 pages; small clarifications and a reference added; to appear in PR
Neutrino-nucleon cross sections at energies of Megaton-scale detectors
An updated set of (anti)neutrino-nucleon charged and neutral current cross
sections at is presented.
These cross sections are of particular interest for the detector optimization
and data processing and interpretation in the future Megaton-scale experiments
like PINGU, ORCA, and Hyper-Kamiokande. Finite masses of charged leptons and
target mass corrections in exclusive and deep inelastic
interactions are taken into account. A new set of QCD NNLO parton density
functions, the ABMP15, is used for calculation of the DIS cross sections. The
sensitivity of the cross sections to phenomenological parameters and to
extrapolations of the nucleon structure functions to small and is
studied. An agreement within the uncertainties of our calculations with
experimental data is demonstrated.Comment: 4 pages, 4 figures, accepted for the VLVnT-2015 Conference
proceedings, will be published on EPJ Web of Conference
Galactic cosmic ray currents and magnetic field irregularity degree in high-speed solar wind streams
Currents of galactic cosmic rays (GCR) obtained by global survey method are analyzed. The cases of almost total disappearance of GCR currents are compared with the results of direct measurements of the solar wind parameters. The conclusion is made on a restricted application of the convective-diffusive mechanism of the GCR modulation by the solar wind during the occurrence of stationary and regular magnetic fields in the interplanetary medium
Detection of Giant Radio Pulses from the Pulsar PSR B0656+14
Giant pulses (GPs) have been detected from the pulsar PSR B0656+14. A pulse
that is more intense than the average pulse by a factor of 120 is encountered
approximately once in 3000 observed periods of the pulsar. The peak flux
density of the strongest pulse, 120 Jy, is a factor of 630 higher than that of
the average pulse. The GP energy exceeds the energy of the average pulse by up
to a factor of 110, which is comparable to that for other known pulsars with
GPs, including the Crab pulsar and the millisecond pulsar PSR B1937+21. The
giant pulses are a factor of 6 narrower than the average pulse and are
clustered at the head of the average pulse. PSR B0656+14 along with PSR
B0031-07, PSR B1112+50, and PSR J1752+2359 belong to a group of pulsars that
differ from previously known ones in which GPs have been detected without any
extremely strong magnetic field on the light cylinder.Comment: 10 pages, 3 figures, 1 table; originally published in Russian in
Pis'ma Astron. Zh., 2006, v.32, 650; translated by George Rudnitskii; the
English version will be appear in Astronomy Letter
- …