Beyond the Standard Model Searches Using a Free Electron Laser

Abstract

Much of the focus of Beyond the Standard Model physics searches is on the TeV scale, making use of hadron and lepton colliders. Additionally, however, there is the means to make these searches in different regions of parameter space using sub-electron volt photons from a Free Electron Laser, for example. We report on the experimental results of searches for opticalwavelength photons mixing with hypothetical hidden-sector paraphotons in the mass range between 10 -5 and 10 -2 electron volts for a mixing parameter greater than 10 -7 . We also report on the results of a sensitive search for scalar coupling of photons to light neutral bosons in the mass range of approximately 1.0 milli-electron volts and coupling strength greater than 10 -6 GeV -1 . These were generation-regeneration experiments using the "light shining through a wall" technique in which regenerated photons are searched for downstream of an optical barrier that separates it from an upstream generation region. The present results indicate no evidence for photon-paraphoton mixing or for scalar couplings of bosons to photons for the range of parameters investigated. OVERVIEW AND RESULTSIf the Standard Model (SM) is part of a more fundamental theory which has some new mass scale, new dynamics and particles could appear and hence signal the new physics associated with it. Popular extensions of the SM motivated by string theory for example, predict a "hidden sector" of particles that interact with the "visible sector" SM fields only with feeble, gravitational-strength couplings [1][2]. This hidden sector can be probed using very high energy accelerators such as the Large Hadron Collider at the TeV scale, and also by laser experiments at the sub-electron volt (sub-eV) energy scale [3][4][5][6][7][8][9][10][11][12][13]. The importance of this study goes beyond even particle physics. A recent suggestion that paraphotons may give rise to a hidden cosmic microwave background (HCMB) [14] indicates that sub-eV particle physics may have direct bearing on cosmological studies. Additionally, several theories in particle physics as well as cosmology predict the existence of at least one scalar, that is, spin-zero, boson [9][10][11][12][13][14][15][16][17][18][19]. Many theories of physics beyond the SM (BSM) can accommodate scalars

Astrophysical searches for a hidden-photon signal in the radio regime

“…Pioneering work on the phenomenology of hidden photons has already focussed on astrophysical implications of low-mass hidden photons [4,5]. Subsequently, evidence for the γ-γ s oscillations has been searched for in a number of laboratory [27][28][29][30][31][32] and astrophysical experiments [8,18,29,[33][34][35][36], focusing in particular on "light shining through the wall" (LSW, [37]) experiments such as ALPS [28] and searches for hidden photons from the Sun (SHIPS; [29,38]). The non-detection of hiddenphoton signals has so far yielded strong bounds on the kinetic mixing parameter χ for a broad range of hiddenphoton masses [7,8,15, and references therein].…”

Cryogenic resonant microwave cavity searches for hidden sector photons

“…One of the most sensitive laboratory-based tests to date is the light shining through a wall (LSW) experiment [8][9][10][11][12][13][14][15][16][17], whereby photons are generated on one side of an impenetrable barrier and then photon detection is attempted on the other side, presumably having crossed the barrier by mixing with paraphotons. In the microwave domain, mode-matched resonant microwave cavities can be used for the generation and detection of photons (emitter and detector cavity respectively) [18].…”