The asymmetry between ordinary matter and antimatter represents one of the great mysteries in modern physics. One promising way to search for answers is to look for violations of fundamental symmetries (CP,T) beyond the Standard Model (SM).
The detection of an electric dipole moment (EDM) of a fundamental particle would directly signal CP violation beyond the SM and grant access to new physics. The current limit on the electron EDM (eEDM) is set by atomic and molecular optics experiments exploiting the giant electric field and unpaired electrons inside polar paramagnetic molecules. Remarkably, high-precision measurements in such low energy experiments, probe mass ranges of proposed CP-violating particles well beyond the direct reach of particle colliders. Molecules at ultracold temperatures are expected to provide several orders of magnitude gain in the eEDM sensitivity, but the strategy to get there is yet unclear.
COMPASS will respond to this need and realize the first ultracold gas of eEDM-sensitive YbCr molecules, combining relativistic ytterbium (Yb) with high-spin chromium (Cr). This specific choice allows the production of large samples and long interrogation times, while granting strong field and an ideal internal structure within each molecule. The success of COMPASS will lead to order-of -magnitude gain in eEDM sensitivity via standard spin-precession measurements, with possible extension to more advanced metrology protocols.
COMPASS is hosted by INRiM-Florence in collaboration with the European Laboratory for Non-Linear Spectroscopy and the University of Florence.
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