Production and detection of very light bosons in the HERA tunnel

Abstract

There are strong theoretical arguments in favour of the existence of very light scalar or pseudoscalar particles beyond the Standard Model which have, so far, remained undetected, due to their very weak coupling to ordinary matter. We point out that after HERA has been decommissioned, there arises a unique opportunity for searches for such particles: a number of HERA's four hundred superconducting dipole magnets might be recycled and used for laboratory experiments to produce and detect light neutral bosons that couple to two photons, such as the axion. We show that, in this way, laser experiments searching for photon regeneration or polarization effects in strong magnetic fields can reach a sensitivity which is unprecedented in pure laboratory experiments and exceeds astrophysical limits from stellar evolution considerations.

Figures (4)

• Figure 1: Exclusion region in mass $m_A$ vs. axion-photon coupling $g_{A\gamma}$ for various current experiments (adapted from Ref. Hagiwara:fs, where also a detailed bibliography can be found) and for the ones proposed in this Letter (labelled as "Laser in HERA tunnel" and "Laser in XFEL tunnel"). The laser experiments aim at both, axion production and detection in the laboratory Semertzidis:1990qcRuoso:1992nxCameron:mr. The microwave cavity experiments aim at axion detection under the assumption that axions are the galactic dark matter DePanfilis:1987dk, the telescope search looks for axions thermally produced in galaxy clusters Bershady:1990sw, and the solar-magnetic Lazarus:1992ry and solar-Germanium Avignone:an experiments search for axions from the sun. The constraint from helium burning (HB) stars arises from a consideration of the energy losses associated with axion production and the corresponding influence on stellar evolution Raffelt:1985nk. It is also shown that two quite distinct invisible axion models, namely the KSVZ Kim:1979if (or hadronic) and the DFSZ Zhitnitsky:1980tq (or grand unified) one, lead to quite similar axion-photon couplings.
• Figure 2: Schematic view of axion production through photon conversion in a magnetic field (left), subsequent travel through a wall, and final detection through photon regeneration (right).
• Figure 3: The Hadron Elektron Ring Anlage HERA at DESY in Hamburg. The HERA tunnel has four straight sections, each of length $\approx 360$ m, at the location of the present experiments.
• Figure 4: The TESLA XFEL campus North-West of the DESY laboratory Materlik:2001qr, whose commissioning is expected in 2011. The XFEL electron beam is accelerated by a dedicated $20$ GeV superconducting linear accelerator starting at a supply hall $\approx 4$ km south of the XFEL laboratory.