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[en] The search for the two-photon decay of light penetrating bosons (axions or others), produced in a nuclear reactor, was supplemented by measurements with a rotatable set-up at the Juelich 10 MW research reactor FRJ-1. Measurements were performed in 'effect' and 'background' positions, the latter not allowing the simultaneous detection of both photons due to decay kinematics. Preliminary measurements, carried out at reactor ON condition only, show no positive effect. (orig.)
[en] Radiative decay of the massive neutrino νi→νiγ (mi>mj) in a constant crossed electromagnetic field is investigated within the framework of the standard electroweak theory. It is shown that the decay is catalyzed by the external field. This effect becomes significant in a strong crossed field (F much-gt Be = m2e/e ≅ 4.41 x 1013 G) and event more pronounced for the ultrarelativistic neutrino (Eν much-gt mν) in a relatively weak field (F much-lt Be). 11 refs., 1 fig
[en] First results are now emerging from a major Fermilab experiment which probes in detail the radiative decays of hyperons - reactions which involve strong, weak and electroweak effects. It is the latest chapter in Fermilab's tradition of detailed hyperon studies
[en] We search for a light Higgs boson A0 in the radiative decay Y(3S) → γA0, A0 → T+T-, T+ → e+νeνT, or T+ → μ+ νμT. The data sample contains 122 x 106 Y(3S) events recorded with the BABAR detector. We find no evidence for a narrow structure in the studied T+T- invariant mass region of 4.03 < mT+T- < 10.10 GeV/c2. We exclude at the 90% confidence level (C.L.) a low-mass Higgs boson decaying to T+T- with a product branching fraction B(Y(3S) → γA0) x B(A0 → T+T-) > (1.5-16) x 10-5 across the mT+T- range. We also set a 90% C.L. upper limit on the T+T- decay of the ηb at B(ηb → T+T-) < 8%.
[en] Radiative νj → νiγ and γ → νi bar νj transitions of massive Dirac neutrinos are studied in the field of a linearly polarized wave and in a constant crossed field within the framework of an invariant procedure being developed for calculations in plane-wave-type fields. It is shown that with the upper bound used for the anomalous magnetic moment of the neutrinos, consideration of the external field may be decisive in the case of the νj → νiγ (mj > mi) photodecay, with possible nontrivial consequences in the astrophysical aspect
[en] In the analysis of rare events a typical question is as follows: does an observed event ti belong to distribution function with some known parameter? The answer is provided by a region of the (0, t) axis (a confidence interval), inside which the event ti occurs with an a priori probability P. It is appropriate to construct an optimal confidence interval (OCI) satisfying the following requirements which secure that this interval contains the observed random quantity most probably: 1) the length of such an interval should be minimal; 2) the probability within such an interval should be maximum; 3) the ratio of the probabilities of the null hypothesis and its alternative should be maximum. The OCI does not exist for any arbitrary distribution function. However, one can construct such an OCI for the exponential distribution F(t, T) = 1 - exp(-t/T), where it equals [0.2 Ť]. Here Ť is an estimate of T. The exponential distribution function is of fundamental importance in the physics of the radioactive decays. The OCI has advantages over usual confidence intervals, since it provides a smaller sum of the Type I and the Type II errors in testing the hypotheses
[en] The radiative decay of to vector mesons ρ and ϕ is calculated in a non-relativistic approach. The results obtained are compared to experimental data to estimate the glue content of . We find a small or nonexistent glue content when our results are compared to the PDG data. However a considerable glue content for was found when we compared our results to the CLAS data.