Bounds on fifth forces from precision measurements on molecules

Abstract

Highly accurate results from frequency measurements on neutral hydrogen molecules H2, HD and D2 as well as the HD + ion can be interpreted in terms of constraints on possible fifth-force interactions. Where the hydrogen atom is a probe for yet unknown lepton-hadron interactions, and the helium atom is sensitive for lepton-lepton interactions, molecules open the domain to search for additional long-range hadron-hadron forces. First principles calculations in the framework of quantum electrodynamics have now advanced to the level that hydrogen molecules and hydrogen molecular ions have become calculable systems, making them a search-ground for fifth forces. Following a phenomenological treatment of unknown hadron-hadron interactions written in terms of a Yukawa potential of the form V5(r) = β exp(−r/λ)/r current precision measurements on hydrogenic molecules yield a constraint β < 1 × 10 −7 eV·Å for long-range hadron-hadron interactions at typical force ranges commensurate with separations of a chemical bond, i.e. λ ≈ 1Å and beyond.

High-precision spectroscopy of the HD+ molecule at the 1-p.p.b. level

“…Therefore, additional experimental data on HD + are needed. In this article, we present the result of a high-precision frequency measurement of the ro-vibrational transition (v, L):(0, 2)→ (8,3) in the HD + molecule and compare it with state-of-the-art molecular theory to find excellent agreement. From this comparison, we subsequently derive new constraints on the size of effects due to possible new physics (in the form of hypothetical fifth forces or compactified higher dimensions [3,4,12]) in HD + , and we determine a value of μ for the first time from a molecular system [12].…”

“…Because of their relative simplicity, molecular hydrogen ions such as H + 2 and HD + are benchmark systems for molecular theory [1,2], and suitable probes of fundamental physical models [3,4]. Already four decades ago, Wing et al [5] performed measurements of ro-vibrational transitions in HD + and conjectured that such measurements could be used to test quantum electrodynamics (QED) theory in molecules and lead to an improved value of the proton-to-electron mass ratio, μ.…”

Absolute frequency determination of molecular transition in the Doppler regime at kHz level of accuracy

“…High precision and accuracy in measurement is required for searching for subtle physical effects and small discrepancies between the experiment and theory [1][2][3]. Spectroscopy of weak molecular transitions, like the O 2 B-band [4] line presented here or the quadrupole transitions in H 2 or D 2 [5], can provide valuable information about molecular structure [6] or verify quantum electrodynamics in molecular systems [7].…”

Forbidden Vibrational Transitions in Cold Molecular Ions: Experimental Observation and Potential Applications

“…The natural linewidth is estimated to be several orders of magnitude smaller (approximately nanohertz [1] ) and the Doppler width at the temperature of the ions amounts to approximately 1. as a possible variation of fundamental physical constants, [16] the existence of yet unknown fundamental interactions [17] or to constrain the magnitude of the electron's electric dipole moment. [18] Many of these questions can suitably be studied with the rotation-vibration spectra of molecules.…”

“…Molecular rotation-vibration transitions show, e.g., a more prominent dependence on a possible variation of the proton to electron mass ratio m p /m e than atomic term energies [19] and they also provide a way to search for unknown long-range hadron-hadron interactions. [17] Indeed, rotation-vibration transitions in N 2 + have been proposed to search for m p /m e variations. [19] Obviously, the accuracy and precision of the measurements needs to be improved for such applications.…”