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Doppler and Sisyphus cooling of 174YbOH are achieved and studied. This polyatomic molecule has high sensitivity to physics beyond the Standard Model and represents a new class of species for future high-precision probes of new T-violating physics. The transverse temperature of the YbOH beam is reduced by nearly two orders of magnitude to < 600 K and the phase-space density is increased by a factor of > 6 via Sisyphus cooling. We develop a full numerical model of the laser cooling of YbOH and find excellent agreement with the data. We project that laser cooling and magneto-optical trapping of long-lived samples of YbOH molecules are within reach and these will allow a high sensitivity probe of the electric dipole moment of the electron. The approach demonstrated here is easily generalized to other isotopologues of YbOH that have enhanced sensitivity to other symmetry-violating electromagnetic moments.

The electric dipole moment of the electron (eEDM) can be measured with high precision using heavy polar molecules. In this paper, we report on a series of new techniques that have improved the statistical sensitivity of the YbF eEDM experiment. We increase the number of molecules participating in the experiment by an order of magnitude using a carefully designed optical pumping scheme. We also increase the detection efficiency of these molecules by another order of magnitude using an optical cycling scheme. In addition, we show how to destabilise dark states and reduce backgrounds that otherwise limit the efficiency of these techniques. Together, these improvements allow us to demonstrate a statistical sensitivity of 1.8 × 10−28 e cm after one day of measurement, which is 1.2 times the shot-noise limit. The techniques presented here are applicable to other high-precision measurements using molecules.

We explore the possibilities for a next-generation electron-electric-dipole-moment experiment using ultracold heteronuclear diatomic molecules assembled from a combination of radium and another laser-coolable atom. In particular, we calculate their ground state structure and their sensitivity to parity- and time-reversal ( P , T ) violating physics arising from flavor-diagonal charge-parity ( CP ) violation. Among these species, the largest P , T -violating molecular interaction constants—associated for example with the electron electric dipole moment—are obtained for the combination of radium (Ra) and silver (Ag) atoms. A mechanism for explaining this finding is proposed. We go on to discuss the prospects for an electron EDM search using ultracold, assembled, optically trapped RaAg molecules, and argue that this system is particularly promising for rapid future progress in the search for new sources of CP violation.

A bstract When the QCD axion is absent in full theory, the strong CP problem has to be explained by an additional mechanism, e.g., the left-right symmetry. Even though tree-level QCD θ ¯ parameter is restricted by the mechanism, radiative corrections to θ ¯ are mostly generated, which leads to a dangerous neutron electric dipole moment (EDM). The ordinary method for calculating the radiative θ ¯ utilizes an equation θ ¯ = − arg det m q loop based on the chiral rotations of complex quark masses. In this paper, we point out that when full theory includes extra heavy quarks, the ordinary method is unsettled for the extra quark contributions and does not contain its full radiative corrections. We formulate a novel method to calculate the radiative corrections to θ ¯ through a direct loop-diagrammatic approach, which should be more robust than the ordinary one. As an application, we investigate the radiative θ ¯ in the minimal left-right symmetric model. We first confirm a seminal result that two-loop level radiative θ ¯ completely vanishes (corresponding to one-loop corrections to the quark mass matrices). Furthermore, we estimate the size of a non-vanishing radiative θ ¯ at three-loop level. It is found that the resultant induced neutron EDM is comparable to the current experimental bound, and the expected size is restricted by the perturbative unitarity bound in the minimal left-right model.

A bstract We present the first complete two-loop calculation of the electric dipole moment of the electron, as well as the rates of the lepton-flavor violating decays μ → e + γ and τ → e/μ + γ , in the unconstrained two-Higgs doublet model. We include the most general Yukawa interactions of the Higgs doublets with the Standard Model fermions up to quadratic order, and allow for generic phases in the Higgs potential. A python implementation of our results is provided via a public git repository.

A bstract We present a discussion of model-independent contributions to the EDM of the electron. We focus on those contributions that emerge from a heavy scalar sector that is linearly realized. In particular, we explore the decoupling limit of the aligned 2HDM. In this model, Barr-Zee diagrams with a fermion loop produce logarithmically-enhanced contributions that are proportional to potentially large new sources of CP violation. In the decoupling limit these contributions are generated by effective dimension-6 operators via the mixing of four-fermion operators into electroweak dipole operators. These logarithmic contributions are not present in more constrained versions of the 2HDM where a Z 2 symmetry is imposed, which then controls the basis of effective operators needed to describe the new physics contributions to the electron EDM. Thus, the Z 2 symmetry provides a suppression mechanism. In the course of the comparison of the results from the aligned 2HDM with the leading logarithms from SMEFT, we needed to specify or correct signs of expressions found in the literature. We then study how the experimental bounds on the electron EDM constrain the set of parameters of the aligned 2HDM.

A bstract Detection of parity P and time-reversal T symmetry-odd electric dipole moments (EDMs) within currently achievable resolution would evidence physics beyond the Standard Model of particle physics. Via the CPT -theorem, which includes charge conjugation C , such low-energy searches complement high-energy physics experiments that probe CP -violation up to the TeV scale. Heavy-elemental atoms and molecules are considered to be among the most promising candidates for a first direct detection of P , T -violation due to enhancement effects that increase steeply with increasing nuclear charge number Z . However, different P , T -odd sources on the subatomic level can contribute to molecular or atomic EDMs, which are target of measurements, and this complicates obtaining rigorous bounds on P , T -violation on a fundamental level. Consequently, several experiments of complementary sensitivity to these individual P , T -odd sources are required for this purpose. Herein, a simply-applicable qualitative model is developed for global analysis of the P , T -odd parameter space from an electronic-structure theory perspective. Rules of thumb are derived for the choice of atoms and molecules in terms of their angular momenta and nuclear charge number. Contrary to naive expectations from Z -scaling laws, it is demonstrated that medium-heavy molecules with Z ≤ 54 can be of great value to tighten global bounds on P , T -violating parameters, in particular, if the number of complementary experiments increases. The model is confirmed by explicit density functional theory calculations of all relevant P , T -odd electronic structure parameters in systems that were used in past experiments or are of current interest for future experiments, respectively: the atoms Xe, Cs, Yb, Hg, Tl, Ra, Fr and the molecules CaOH, SrOH, YO, CdH, BaF, YbF, YbOH, HfF + , WC, TlF, PbO, RaF, ThO, ThF + and PaF 3+ .

A bstract Dark sectors provide beyond Standard Model scenarios which can address unresolved puzzles, such as the observed dark matter abundance or the baryon asymmetry of the Universe. A naturally small portal to the dark sector is obtained if dark-sector interactions stem from a non-Abelian hidden gauge group that couples through kinetic mixing with the hypercharge boson. In this work, we investigate the phenomenology of such a portal of dimension five in the presence of CP violation, focusing on its signatures in fermion electric dipole moments. We show that, currently unbounded regions of the parameter space from dark photon searches can be indirectly probed with upcoming electron dipole moment experiments for dark boson masses in the range 1 − 100 GeV. We also discuss two particular scenarios where a SU(2) D dark gauge group spontaneously breaks into either an Abelian U(1) D or nothing. In both cases, we show that potentially observable electron dipole moments can be produced in vast regions of the parameter space compatible with current experimental constraints and observed dark matter abundance.

A bstract We study two Higgs doublet models with successful electroweak baryogenesis but without cancellations of electric dipole moments (EDMs). For the baryogenesis, additional scalar bosons are favored to couple mainly with the top quark with CP violations. However, if they also couple to light fermions of the Standard Model, the model is limited severely by EDMs, and additional CP phases irrelevant to the baryogenesis are often introduced to cancel the contributions to the EDMs. Alternatively, we consider a scenario where the light-fermion couplings are suppressed to avoid the constraints. In our scenario, it is found that the leading contributions arise in the top-quark EDMs at the two-loop level. They induce the electron, neutron, and proton EDMs via radiative corrections. Since there is no additional CP-violating phase, they are correlated with the baryon asymmetry. We show that our scenario is compatible with the current experimental bounds and is within the scope of future EDM experiments.

A bstract Axions are introduced to explain the observed smallness of the θ ¯ term of QCD. Standard Model extensions typically contain new sources of CP violation, for instance to account for the baryon asymmetry of the universe. In the presence of additional CP-violating sources a Peccei-Quinn mechanism does not remove all CP violation, leading to CP-odd interactions among axions and Standard Model fields. In this work, we use effective field theory to parametrize generic sources of beyond-the-Standard-Model CP violation. We systematically compute the resulting CP-odd couplings of axions to leptons and hadrons by using chiral perturbation theory. We discuss in detail the phenomenology of the CP-odd axion couplings and compare limits from axion searches, such as fifth force and monopole-dipole searches and astrophysics, to direct limits on the CP-violating operators from electric dipole moment experiments. While limits from electric dipole moment searches are tight, the proposed ARIADNE experiment can potentially improve the existing constraints in a window of axion masses.