Extended search for sub-eV axion-like resonances via four-wave mixing with a quasi-parallel laser collider in a high-quality vacuum system

Abstract

<jats:title>Abstract</jats:title> <jats:p>Resonance states of axion-like particles were searched for via four-wave mixing by focusing two-color pulsed lasers into a quasi-vacuum. A quasi-parallel collision system that allows probing of the sub-eV mass range was realized by focusing the combined laser fields with an off-axis parabolic mirror. A 0.10 mJ/34 fs Ti:sapphire laser pulse and a 0.14 mJ/9 ns Nd:YAG laser pulse were spatiotemporally synchronized by sharing a common optical axis and focused into the vacuum system. No significant four-wave mixing signal was observed at the vacuum pressure of $3.7 \times 10^{-5}$ Pa, thereby providing upper bounds on the coupling-mass relation by assuming exchanges of scalar and pseudoscalar fields at a 95% confidence level in the mass range below 0.21 eV. For this search, the experimental setup was substantially upgraded so that the optical components were compatible with the requirements of the high-quality vacuum system, hence enabling the pulse power to be increased. With the increased pulse power, a new kind of pressure-dependent background photon emerged in addition to the known atomic four-wave mixing process. This paper shows the pressure dependence of these background photons and how to handle them in the search.</jats:p>

Search for sub-eV axion-like resonance states via stimulated quasi-parallel laser collisions with the parameterization including fully asymmetric collisional geometry

“…In this paper, we report new results for sub-eV ALP searches by combining linearly and circularly polarized states for the creation and inducing lasers, respectively, based on the parameterization including the fully asymmetric collision geometry in QPS. This is in contrast to previous works in which we reported searches based on the symmetric QPS approximation with linear polarization states for both the creation and inducing lasers [28][29][30].…”

“…In past searches [28][29][30], we provided constraints on the coupling-mass relation based on a symmetric QPS interpretation in which the incident angles and energies of the two initial-state photons are symmetric (figure 1). Based on this parameterization, we provided…”

Search for sub-eV axion-like resonance states via stimulated quasi-parallel laser collisions with the parameterization including fully asymmetric collisional geometry

“…In this paper, we report new results for sub-eV ALP searches by combining linearly and circularly polarized states for the creation and inducing lasers, respectively, based on the parameterization including the fully asymmetric collision geometry in QPS. This is in contrast to previous works in which we reported searches based on the symmetric QPS approximation with linear polarization states for both the creation and inducing lasers [16][17][18].…”

“…In past searches [16][17][18], we provided constraints on the coupling-mass relation based on a symmetric QPS interpretation in which the incident angles and energies of the two initial-state photons are symmetric (Fig. 1).…”

Stimulated radar collider for probing gravitationally weak coupling pseudo Nambu-Goldstone bosons

“…The second key element is the enhancement of the interaction rate by the technique discussed in appendix, which relies on the stimulated nature of the two-body photon-photon scattering process, adding a coherently co-propagating field as the inducing field. Among several possible collision geometries [5][6][7][8][9], QPS is the optimum geometry for the low mass range, having the widest accessible mass range possible for a single collision geometry. For simplicity, we have initially considered QPS with a symmetric incident angle ϑ, as shown in figure 1a [5].…”