A search for resonant absorption of the solar axion by $^{83}rm{Kr}$ nuclei was performed using the proportional counter installed inside the low-background setup at the Baksan Neutrino Observatory. The obtained model independent upper limit on the combination of isoscalar and isovector axion-nucleon couplings $|g_3-g_0|leq 8.4times 10^{-7}$ allowed us to set the new upper limit on the hadronic axion mass of $m_{A}leq 65$ eV (95% C.L.) with the generally accepted values $S$=0.5 and $z$=0.56.
A search for resonant absorption of the solar axion by $^{83}rm{Kr}$ nuclei was performed using the proportional counter installed inside the low-background setup at the Baksan Neutrino Observatory. The obtained model independent upper limit on the combination of isoscalar and isovector axion-nucleon couplings $|g_3-g_0|leq 1.69times 10^{-6}$ allowed us to set the new upper limit on the hadronic axion mass of $m_{A}leq 130$ eV (95% C.L.) with the generally accepted values $S$=0.5 and $z$=0.56.
We analyze the data from two recent experiments designed to search for solar axions within the context of multidimensional theories of the Kaluza-Klein type. In these experiments, axions were supposed to be emitted from the solar core, in M1 transitions between the first excited state and the ground state of 57Fe and 7Li. Because of the high multiplicity of axionic Kaluza-Klein states which couple with the strength of ordinary QCD axions, we obtain much more stringent experimental limits on the four-dimensional Peccei-Quinn breaking scale f_{PQ}, compared with the solar QCD axion limit. Specifically, for the 57Fe experiment, f_{PQ}>1x10^6 GeV in theories with two extra dimensions and a higher-dimensional gravitational scale M_H of order 100 TeV, and f_{PQ}>1x10^6 GeV in theories with three extra dimensions and M_H of order 1 TeV (to be compared with the QCD axion limit, f_{PQ}>8x10^3 GeV). For the 7Li experiment, f_{PQ}>1.4x10^5 GeV and 3.4x10^5 GeV, respectively (to be compared with the QCD axion limit, f_{PQ}>1.9x10^2 GeV). It is an interesting feature of our results that, in most cases, the obtained limit on f_{PQ} cannot be coupled with the mass of the axion, which is essentially set by the (common) radius of the extra dimensions.
A search for axioelectric absorption of solar axions produced in the $ p + d rightarrow {^3rm{He}}+gamma~(5.5~ rm{MeV})$ reactions has been performed with a BGO detector placed in a low-background setup. A model-independent limit on an axion-nucleon and axion-electron coupling constant has been obtained: $| g_{Ae}times g_{AN}^3|< 1.9times 10^{-10}$ for 90% confidence level. The constrains of the axion-electron coupling have been obtained for hadronic axion with masses in (0.1 - 1) MeV range: $|g_{Ae}| leq (0.96 - 8.2)times 10^{-8}$.
We have searched for axions which could be produced in the solar core by exploiting their conversion to X rays in a strong laboratory magnetic field. The signature of the solar axion is an increase in the rate of the X rays detected in a magnetic helioscope when the sun is within its acceptance. From the absence of such a signal we set a 95% confidence level limit on the axion coupling to two photons $g_{agammagamma}equiv 1/M < 6.0times 10^{-10}$ GeV$^{-1}$, provided the axion mass $m_a<0.03$ eV. The limit on the coupling is factor 4.5 more stringent than the recent experimental result. This is the first experiment whose sensitivity to $g_{agammagamma}$ is higher than the limit constrained by the solar age consideration.
We have searched for hadronic axions which may be produced in the Sun by a bremsstrahlung-like process, and observed in the HPGe detector by an axioelectric effect. A conservative upper limit on the hadronic axion mass m_a < 334 eV at 95% C.L. is obtained. Our experimental approach is based on the axion-electron coupling and it does not include the axion-nucleon coupling, which suffers from the large uncertainties related to the estimation of the flavor-singlet axial-vector matrix element.
A.V. Derbin
,I.S. Drachnev
,A.M. Gangapshev
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(2017)
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"Recent results of search for solar axions using resonant absorption by $^{83}$Kr nuclei"
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Alexander Derbin
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