289 research outputs found

    Dark matter and Higgs boson physics

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    A vector-like colorless fermion doublet and a singlet added to the Standard Model allow a consistent interpretation of dark matter in terms of the lightest neutral particle, as they may help in obtaining successful gauge coupling unification. We analyze in detail the mass range of the lightest neutral particle below the W mass, i.e. in a range of the parameters where the physics of the Standard Model Higgs boson may be substantially affected either directly or indirectly.Comment: 17 pages, 7 figures. v3: published version (small corrections

    Guidelines for axion identification in astrophysical observations

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    The origin of various celestial phenomena have remained mysterious for conventional astrophysics. Therefore, alternative solutions should be considered, taking into account the involvement of unstable dark-matter particle candidates, such as the celebrated axions or other as yet unforeseen axion-like particles. Their spontaneous and induced decay by the ubiquitous solar magnetic fields can be at the origin of persisting enigmatic X-ray emission, giving rise to a steady and a transient/local solar activity, respectively. The (coherent) conversion of photons into axion(-like) particles in intrinsic magnetic fields may modify the solar axion spectrum. The reversed process can be behind transient (solar) luminosity deficits in the visible. Then, the Sun might be also a strong source of ~eV-axions. Thus, enigmatic observations might be the as yet missing direct signature for axion(-like) particles in earth-bound detectors.Comment: 6 pages, to be submitted to JCA

    First axion dark matter search with toroidal geometry

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    We firstly report an axion haloscope search with toroidal geometry. In this pioneering search, we exclude the axion-photon coupling gaő≥ő≥g_{a\gamma\gamma} down to about 5√ó10‚ąí85\times10^{-8} GeV‚ąí1^{-1} over the axion mass range from 24.7 to 29.1 őľ\mueV at a 95\% confidence level. The prospects for axion dark matter searches with larger scale toroidal geometry are also considered.Comment: 5 pages, 5 figures, 1 table and to appear in PRD-R

    KWISP: an ultra-sensitive force sensor for the Dark Energy sector

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    An ultra-sensitive opto-mechanical force sensor has been built and tested in the optics laboratory at INFN Trieste. Its application to experiments in the Dark Energy sector, such as those for Chameleon-type WISPs, is particularly attractive, as it enables a search for their direct coupling to matter. We present here the main characteristics and the absolute force calibration of the KWISP (Kinetic WISP detection) sensor. It is based on a thin Si3N4 micro-membrane placed inside a Fabry-Perot optical cavity. By monitoring the cavity characteristic frequencies it is possible to detect the tiny membrane displacements caused by an applied force. Far from the mechanical resonant frequency of the membrane, the measured force sensitivity is 5.0e-14 N/sqrt(Hz), corresponding to a displacement sensitivity of 2.5e-15 m/sqrt(Hz), while near resonance the sensitivity is 1.5e-14 N/sqrt(Hz), reaching the estimated thermal limit, or, in terms of displacement, 7.5e-16 N/sqrt(Hz). These displacement sensitivities are comparable to those that can be achieved by large interferometric gravitational wave detectors.Comment: 9 pages, 8 figures in colo

    Resonance method of electric-dipole-moment measurements in storage rings

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    A resonance method of measuring the electric dipole moment (EDM) of nuclei in storage rings is described, based on two new ideas: (1) Oscillating particles' velocities in resonance with spin precession, and (2) alternately producing two sub-beams with different betatron tunes--one sub-beam to amplify and thus make it easier to correct ring imperfections that produce false signals imitating EDM signals, and the other to make the EDM measurement.Comment: 10 pages, 1 figure, accepted for publication in Phys. Rev. Lett., Spring 200
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