Progress toward an ultracold trap of SrOH molecules to probe fundamental constant variations and the electron electric dipole moment

We present experimental progress towards laser slowing and trapping of SrOH molecules. The long coherence times possible in a trapped, ultracold sample will enable two complementary searches for beyond-the-Standard-Model physics. First, because vibrational and rotational energies of molecules generically depend on the proton-to-electron mass ratio, μ, certain dark matter models that induce oscillations in μ can be probed via precision spectroscopy of rovibrational transitions. A low-lying accidental near-degeneracy between stretching and bending vibrational states in SrOH can be probed with experimentally convenient microwave transitions. Second, the nearly-degenerate opposite-parity states of the bending vibrational mode provide access to the moderate effective electric field of 2 GV/cm at small externally applied fields, and also serve as co-magnetometer states. Combined with the long coherence times and large numbers possible in a trap of ultracold SrOH molecules, we anticipate competitive sensitivity to the electron electric dipole moment. We describe recent developments of the experimental apparatus, including a new cryogenic buffer gas beam source, the full laser slowing and cooling system comprised of 10 sum-frequency-generated lasers, and work toward 2D transverse cooling for increased loading efficiency into a magneto-optical trap.