2,969 research outputs found
Cosmic ray sidereal diurnal variation of galactic origin observed by neutron monitors
Cosmic ray sidereal diurnal variations observed by neutron monitors are analyzed for the period 1961 to 1978, by adding 134 station years data to the previous paper (Nagashima, et al., 1983). Also the dependence of the sidereal variations on Sun's polar magnetic field polarity is examined for two periods; the period of negative polarity in the northern region, 1961 to 1969 and the period of positive polarity, 1970 to 1978. It is obtained that for the former period, the amplitude A=0.0203 + or 0.0020% and the phase phi=6.1 + or - 0.4 h LST and for the latter period, 0.0020% and phi=8.6 + or - 4 h LST, respectively
Pickoff and spin-conversion quenchings of ortho-positronium in oxygen
The quenching processes of the thermalized ortho-positronium(o-Ps) on an
oxygen molecule have been studied by the positron annihilation age-momentum
correlation techinique(AMOC). The Doppler broadening spectrum of the 511 keV
gamma-rays from the 2gamma annihilation of o-Ps in O_2 has been measured as a
function of the o-Ps age. The rate of the quenching, consisting of the pickoff
and the spin-conversion, is estimated from the positron lifetime spectrum. The
ratio of the pickoff quenching rate to the spin-conversion rate is deduced from
the Doppler broadening of the 511 keV gamma-rays from the annihilation of the
o-Ps. The pickoff parameter ^1Z_eff, the effective number of the electrons per
molecule which contribute to the pickoff quenching, for O_2 is determined to be
0.6 +- 0.4. The cross-section for the elastic spin-conversion quenching is
determined to be (1.16 +- 0.01) * 10^{-19} cm^2.Comment: 4 pages with 5 eps figures, LaTeX2e(revtex4
CP Violation in Three-Body Chargino Decays
CP violation in supersymmetry can give rise to rate asymmetries in the decays
of supersymmetric particles. In this work we compute the rate asymmetries for
the three-body chargino decays \tilde\chi^\pm_2 \to \tilde\chi^\pm_1 HH,
\tilde\chi^\pm_2 \to \tilde\chi^\pm_1 ZZ, \tilde\chi^\pm_2 \to \tilde\chi^\pm_1
W^+ W^- and \tilde\chi^\pm_2 \to tilde\chi^\pm_1 ZH. Each of the decays
contains contributions mediated by neutral Higgs bosons that can possibly go on
shell. Such contributions receive a resonant enhancement; furthermore, the
strong phases required for the CP asymmetries come from the widths of the
exchanged Higgs bosons. Our results indicate that the rate asymmetries can be
relatively large in some cases, while still respecting a number of important
low-energy bounds such as those coming from B meson observables and electric
dipole moments. For the parameters that we consider, rate asymmetries of order
10% are possible in some cases.Comment: 17 pages, 4 figures, published versio
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