CP-violation and electric dipole moments

Searches for intrinsic electric dipole moments of nucleons, atoms and molecules are precision flavour-diagonal probes of new -odd physics. We review and summarise the effective field theory analysis of the observable EDMs in terms of a general set of CP-odd operators at 1 GeV, and the ensuing model-independent constraints on new physics. We also discuss the implications for supersymmetric models, in light of the mass limits emerging from the LHC.     

Relation between electric quadrupole and magnetic dipole nuclear moments

The values of electric quadrupole moments are described by gyromagnetic ratios of bound and free nucleons. A comparison with the experimental data shows an agreement within 15% for non-magic strongly deformed nuclei and within 50% for other ones. The expressions obtained are sensitive to a change in the order of subshell filling which takes place for proton and neutron subshells near Fermi surface.     

Rotational spectra of quinoline and of isoquinoline: spectroscopic constants and electric dipole moments

Rotational spectra of quinoline and of isoquinoline have been observed in the centimeter- and millimeter-wave regions. The spectra were assigned on the basis of bands formed by high-J transitions, which were measured up to J″?128 and ν?234 GHz. Complementary measurements were also made on low-J, centimeter-wave spectra observed in supersonic expansion and with fully resolved nuclear quadrupole hyperfine structure. Accurate rotational, centrifugal distortion and hyperfine splitting constants for the ground states of both molecules are reported. The electric dipole moments for the two molecules were also determined from Stark effect measurements and are μ_a=0.14355(19), μ_b=2.0146(17), μ_tot=2.0197(17) D for quinoline, and μ_a=2.3602(21), μ_b=0.9051(14), μ_tot=2.5278(20) D for isoquinoline. The experimental observables were found to be rather accurately predicted by MP2/6-31G** ab initio calculations, and corresponding molecular geometries are also reported.     

Additional stringy sources for electric dipole moments

We show that string models with low energy supersymmetry which accommodate the fermion mass hierarchy generally give nonuniversal soft trilinear couplings (A terms). In conjunction with the apparently large Cabibbo-Kobayashi-Maskawa (CKM) phase, this results in large fermion electric dipole moments (EDMs) even in the absence of CP violating phases in the supersymmetry breaking auxiliary fields and the micro term. Nonobservation of the EDMs therefore implies that strings select special flavor and/or supersymmetry breaking patterns.     

Higgs-boson two-loop contributions to electric dipole moments in the MSSM

The complete set of Higgs-boson two-loop contributions to electric dipole moments of the electron and neutron is calculated in the minimal supersymmetric standard model. The electric dipole moments are induced by CP-violating trilinear couplings of the `CP-odd' and charged Higgs bosons to the scalar top and bottom quarks. Numerical estimates of the individual two-loop contributions to electric dipole moments are given.     

The relative electric dipole moments of singlets and triplets

A sensitivity analysis formalism is constructed for collinear reactive systems with multiple electronic potential energy surfaces. The work extends the sphere of application of sensitivity theory into the reactive domain. Expressions are obtained for the first order elementary sensitivity coefficients (i.e. partial derivatives) of both the reactive and non-reactive component elements of the scattering matrix with respect to an arbitrary system parameter. In the case of the non-reactive elements, the sensitivity coefficients involve essentially the piecewise integration of a function matrix containing the available solution of the scattering problem. The reactive sensitivity coefficients draw on both forward and backward propagated solutions. The paper concludes with a discussion of the scope and applicability of reactive sensitivity analysis.     

Search for electric dipole moments at storage rings

Twenty years ago, we published a paper entitled “Discovery of antiproton trapping by long-lived metastable states in liquid helium”. In retrospect, this was the discovery of antiprotonic helium atoms, the study of which is actively being done at CERN’s antiproton decelerator. A brief overview of this interesting exotic atom is given, together with some historical background.     

Nuclear electric dipole moments at ion storage rings

Upper limits on the electric dipole moments (EDM) of elementary particles and atoms are presented, and their physical implications are discussed. The implications following from the neutron and atomic experiments are of comparable interest. The nuclear EDMs can be studied at ion storage rings, with the expected sensitivity much better than . This would represent a serious progress in studies of the CP-violation problem. This revised version was published online in August 2006 with corrections to the Cover Date.     

Flavour-dependent CP violation and natural suppression of the electric dipole moments

We revisit the supersymmetric CP problem and find that it can be naturally resolved if the origin of CP violation is closely related to the origin of flavour structures. In this case, the supersymmetry breaking dynamics do not bring in any new CP-violating phases. This mechanism requires hermitian Yukawa matrices which naturally arise in models with a U(3) flavour symmetry. The neutron electric dipole moment (NEDM) is predicted to be within one-two orders of magnitude below the current experimental limit. The model also predicts a strong correlation between A_CP(b→sγ) and the NEDM. The strong CP problem is mitigated although not completely solved.     

New method of measuring electric dipole moments in storage rings

A new highly sensitive method of looking for electric dipole moments of charged particles in storage rings is described. The major systematic errors inherent in the method are addressed and ways to minimize them are suggested. It seems possible to measure the muon EDM to levels that test speculative theories beyond the standard model.     

Bino-driven electroweak baryogenesis with highly suppressed electric dipole moments

It is conventional wisdom that successful electroweak baryogenesis in the Minimal Supersymmetric extension of the Standard Model (MSSM) is in tension with the non-observation of electric dipole moments (EDMs), since the level of CP-violation responsible for electroweak baryogenesis is believed to generate unavoidably large EDMs. We show that CP-violation in the bino–Higgsino sector of the MSSM can account for successful electroweak baryogenesis without inducing large EDMs. This observation weakens the correlation between electroweak baryogenesis and EDMs, and makes the bino-driven electroweak baryogenesis scenario the least constrained by EDM limits. Taking this observation together with the requirement of a strongly first-order electroweak phase transition, we argue that a bino-driven scenario with a light stop is the most phenomenologically viable MSSM electroweak baryogenesis scenario.     

Effects of electric dipole,anapole, and neutral weak magnetic moments of a proton in the polarized electron-proton electroweak scattering

We have derived and investigated analytical expressions for the cross sections and spin asymmetries in the elastic electromagnetic and electroweak scattering of unpolarized/longitudinally polarized electrons on a polarized/unpolarized proton target with allowance for the C-, P-, and T/CP-invariance violating anapole and electric dipole moments, as well as the neutral weak electric, magnetic, and axial form factors of the proton. The dependence of the spin asymmetries on the energy and form-factor parameters is studied.     

Comment on the critical dipole moments for electron binding to a freely rotating electric dipole

In this paper the reference hypernetted-chain (RHNC) theory is solved for fluids of Stockmayer (dipolar Lennard-Jones) particles and detailed comparisons are made with computer simulation results. It is shown that the RHNC approximation significantly improves upon integral equation theories previously solved for Stockmayer systems. In particular the static dielectric constants obtained are in much better agreement with the computer simulations.     

Search for electric dipole moments of light ions in storage rings

The Standard Model (SM) of Particle Physics is not capable to account for the apparent matterantimatter asymmetry of our Universe. Physics beyond the SM is required and is searched for by (i) employing highest energies (e.g., at LHC), and (ii) striving for ultimate precision and sensitivity (e.g., in the search for electric dipole moments (EDMs)). Permanent EDMs of particles violate both time reversal (T) and parity (P) invariance, and are via the CPT-theorem also CP-violating. Finding an EDM would be a strong indication for physics beyond the SM, and pushing upper limits further provides crucial tests for any corresponding theoretical model, e.g., SUSY. Direct searches of proton and deuteron EDMs bear the potential to reach sensitivities beyond 10^?29 e cm. For an all-electric proton storage ring, this goal is pursued by the US-based srEDM collaboration [2], while the newly found Julich-based JEDI collaboration [1] is pursuing an approach using a combined electric-magnetic lattice which shall provide access to the EDMs of protons, deuterons, and ³He ions in the same machine. In addition, JEDI has recently proposed to perform a direct measurement of the proton and/or deuteron EDM at COSY using resonant techniques involving Wien filters.     

Intrinsic electric dipole moments of paramagnetic atoms: rubidium and cesium

The electric dipole moment (EDM) of paramagnetic atoms is sensitive to the intrinsic EDM contribution from that of its constituent electrons and a scalar-pseudoscalar (S-PS) electron-nucleus interaction. The electron EDM and the S-PS contributions to the EDMs of these atoms scale as approximately Z;{3}. Thus, the heavy paramagnetic atoms will exhibit large EDM enhancement factors. However, the sizes of the couplings are so small that they are of interest of high precision atomic experiments. In this work we have computed the EDM enhancement factors of the ground states of Rb and Cs due to both the electron EDM and the S-PS EDM using the relativistic coupled-cluster theory. The importance of determining precise ab initio enhancement factors and experimental results of atomic EDMs in deducing a reliable limit on the electron EDM is emphasized.