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Register a new userSolar Kaluza-Klein axion search with NEWS-G
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Added by
Francisco Vazquez De Sola Fernandez
Publication date
2021
fields
Physics
and research's language is
English
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Kaluza-Klein (KK) axions appear in theories with extra dimensions as higher mass, significantly shorter lifetime, excitations of the Peccei-Quinn axion. When produced in the Sun, they would remain gravitationally trapped in the solar system, and their decay to a pair of photons could provide an explanation of the solar corona heating problem. A low-density detector would discriminate such a signal from the background, by identifying the separation of the interaction point of the two photons. The NEWS-G collaboration uses large volume Spherical Proportional Counters, gas-filled metallic spheres with a spherical anode in their centre. After observation of a single axion-like event in a 42 day long run with the SEDINE detector, a $90%$ C.L. upper limit of $g_{agammagamma}<7.76cdot10^{-13},GeV^{-1}$ is set on the axion-photon coupling for a KK axion density on Earth of $n_{a}=4.07cdot10^{13},m^{-3}$ and two extra dimensions of size $R = 1,eV^{-1}$.
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In theories with the large extra dimensions beyond the standard 4-dimensional spacetime, axions could propagate in such extra dimensions, and acquire Kaluza-Klein (KK) excitations. These KK axions are produced in the Sun and could solve unexplained heating of the solar corona. While most of the solar KK axions escape from the solar system, a small fraction is gravitationally trapped in orbits around the Sun. They would decay into two photons inside a terrestrial detector. The event rate is expected to modulate annually depending on the distance from the Sun. We have searched for the annual modulation signature using $832times 359$ kg$cdot$days of XMASS-I data. No significant event rate modulation is found, and hence we set the first experimental constraint on the KK axion-photon coupling of $4.8 times 10^{-12}, mathrm{GeV}^{-1}$ at 90% confidence level for a KK axion number density of $bar{n}_mathrm{a} = 4.07 times 10^{13}, mathrm{m}^{-3}$, the total number of extra dimensions $n = 2$, and the number of extra dimensions $delta = 2$ that axions can propagate in.
We present results from a search for solar axions with the COSINE-100 experiment. We find no evidence of solar axion events from a data-set of 6,303.9 kg$cdot$days exposure and set a 90,% confidence level upper limit on the axion-electron coupling, $g_{ae}$, at 1.70~$times$~$10^{-11}$ for an axion mass less than 1,keV/c$^2$. This limit excludes QCD axions heavier than 0.59,eV/c$^2$ in the DFSZ model and 168.1,eV/c$^2$ in the KSVZ model.
The CERN Axion Solar Telescope (CAST) has finished its search for solar axions with 3^He buffer gas, covering the search range 0.64 eV < m_a <1.17 eV. This closes the gap to the cosmological hot dark matter limit and actually overlaps with it. From the absence of excess X-rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g_ag < 3.3 x 10^{-10} GeV^{-1} at 95% CL, with the exact value depending on the pressure setting. Future direct solar axion searches will focus on increasing the sensitivity to smaller values of g_a, for example by the currently discussed next generation helioscope IAXO.
The CAST (CERN Axion Solar Telescope) experiment is searching for solar axions by their conversion into photons inside the magnet pipe of an LHC dipole. The analysis of the data recorded during the first phase of the experiment with vacuum in the magnet pipes has resulted in the most restrictive experimental limit on the coupling constant of axions to photons. In the second phase, CAST is operating with a buffer gas inside the magnet pipes in order to extent the sensitivity of the experiment to higher axion masses. We will present the first results on the $^{4}{rm He}$ data taking as well as the system upgrades that have been operated in the last year in order to adapt the experiment for the $^{3}{rm He}$ data taking. Expected sensitivities on the coupling constant of axions to photons will be given for the recent $^{3}{rm He}$ run just started in March 2008.
The status of the solar axion search with the CERN Axion Solar Telescope (CAST) will be presented. Recent results obtained by the use of $^3$He as a buffer gas has allowed us to extend our sensitivity to higher axion masses than our previous measurements with $^4$He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV$ le m_{a} le $ 0.64 eV. From the absence of an excess of x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g$_{agamma} le 2.3times 10^{-10}$ GeV$^{-1}$ at 95% C.L., the exact value depending on the pressure setting. CAST published results represent the best experimental limit on the photon couplings to axions and other similar exotic particles dubbed WISPs (Weakly Interacting Slim Particles) in the considered mass range and for the first time the limit enters the region favored by QCD axion models. Preliminary sensitivities for axion masses up to 1.16 eV will also be shown reaching mean upper limits on the axion-photon coupling of g$_{agamma} le 3.5times 10^{-10}$ GeV$^{-1}$ at 95% C.L. Expected sensibilities for the extension of the CAST program up to 2014 will be presented. Moreover long term options for a new helioscope experiment will be evoked.
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