The electric dipole moment of the neutron in chiral perturbation theory

We calculate the electric dipole moments of the neutron and the Lambda within the framework of heavy baryon chiral perturbation theory. They are induced by strong CP-violating terms of the effective Lagrangian in the presence of the vacuum angle theta_0. The construction of such a Lagrangian is outlined and we are able to give an estimate for theta_0.Comment: 17 pages, 2 figure

Chiral Estimates of Strong CP Violation Revisited

The effects of the CP violating $\theta$ term in the QCD Lagrangian upon low energy hadronic phenomenology are reconsidered. Strong CP violating interactions among Goldstone bosons and octet baryons are incorporated into an effective chiral Lagrangian framework. The $\theta$ term's impact upon the decays $\eta\to\pi\pi$ and $\pi^0\to\gamma\gamma$ is then investigated but found to be extremely small. A refined model independent estimate of nonanalytic contributions to the neutron electric dipole moment is also determined using velocity dependent Baryon Chiral Perturbation Theory. We obtain the approximate upper bound $|\theta| < 4.5 \times 10^{-10}$.Comment: 11 pages with 3 figures not included but available upon request, CALT-68-184

On the CP-odd Nucleon Potential

The CP-odd nucleon potential for different models of CP violation in the one meson exchange approximation is studied. It is shown that the main contribution is due to the $\pi$-meson exchange which leads to a simple one parameter CP-odd nucleon potential.Comment: 12 pages, RevTex, UM-P-92/114, OZ-92/3

Topological susceptibility in full QCD at zero and finite temperature

We present a study of the topological susceptibility $\chi$ on the lattice for full QCD with 2 and 4 flavours of staggered fermions at zero and finite temperature T. We find that $\chi$ presents a sharp drop across the deconfinement transition. We also study the dependence of $\chi$ on the quark mass at T=0: we have no conclusive evidence for the expected chiral behaviour.Comment: latex source, 8 pages, 4 figure

Lattice Perturbation Theory by Computer Algebra: A Three-Loop Result for the Topological Susceptibility

We present a scheme for the analytic computation of renormalization functions on the lattice, using a symbolic manipulation computer language. Our first nontrivial application is a new three-loop result for the topological susceptibility.Comment: 15 pages + 2 figures (PostScript), report no. IFUP-TH 31/9

Correlator of Topological Charge Densities in Instanton Model in QCD

The QCD sum rule for the correlator of topological charge densities and related to it longitudinal part of the correlator of singlet axial currents is considered in the framework of instanton model. The coupling constant of eta'-meson with the singlet axial current is determined. Its value appears to be in a good coincidence with the value determined recently from the connection of the part of proton spin, carried by u,d,s quarks, with the derivative of QCD topological susceptibility. From the same sum rule eta-eta' mixing angle is found in the framework of two mixing angles model. Its value is close to that found in the chiral effective theory. The correlator of topological charge densities at large momenta is calculated.Comment: 14 pages, 2 figure

The neutron electric dipole form factor in the perturbative chiral quark model

We calculate the electric dipole form factor of the neutron in a perturbative chiral quark model, parameterizing CP-violation of generic origin by means of effective electric dipole moments of the constituent quarks and their CP-violating couplings to the chiral fields. We discuss the relation of these effective parameters to more fundamental ones such as the intrinsic electric and chromoelectric dipole moments of quarks and the Weinberg parameter. From the existing experimental upper limits on the neutron EDM we derive constraints on these CP-violating parameters.Comment: 20 pages, 3 figure

CP-odd Phase Correlations and Electric Dipole Moments

We revisit the constraints imposed by electric dipole moments (EDMs) of nucleons and heavy atoms on new CP-violating sources within supersymmetric theories. We point out that certain two-loop renormalization group corrections induce significant mixing between the basis-invariant CP-odd phases. In the framework of the constrained minimal supersymmetric standard model (CMSSM), the CP-odd invariant related to the soft trilinear A-phase at the GUT scale, theta_A, induces non-trivial and distinct CP-odd phases for the three gaugino masses at the weak scale. The latter give one-loop contributions to EDMs enhanced by tan beta, and can provide the dominant contribution to the electron EDM induced by theta_A. We perform a detailed analysis of the EDM constraints within the CMSSM, exhibiting the reach, in terms of sparticle spectra, which may be obtained assuming generic phases, as well as the limits on the CP-odd phases for some specific parameter points where detailed phenomenological studies are available. We also illustrate how this reach will expand with results from the next generation of experiments which are currently in development.Comment: 31 pages, 21 eps figures; v2: additional remarks on 2-loop threshold corrections and references added; v3: typos corrected, to appear in Phys. Rev.

Constraining CP Violating Phases of the MSSM

Possible CP violation in supersymmetric (SUSY) extensions of the Standard Model (SM) is discussed. The consequences of CP violating phases in the gaugino masses, trilinear soft supersymmetry-breaking terms and the `mu' parameter are explored. Utilizing the constraints on these parameters from electron and neutron electric dipole moments, possible CP violating effects in B-physics are shown. A set of measurements from the B-system which would overconstrain the above CP violating phases is illustrated.Comment: 14 pages, 6 figure

CP violation from noncommutative geometry

If the geometry of space-time is \nc, i.e. $[x_{\mu},x_{\nu}]=i \theta_{\mu \nu}$, then \nc \cpviolng effects may be manifest at low energies. For a \nc scale $\Lambda \equiv \theta^{-1/2} \leq 2 TeV$, \cpviol from \ncg is comparable to that from the Standard Model (SM) alone: the \nc contributions to $\epsilon$ and $\epsilon'/\epsilon$ in the $K$-system, may actually dominate over the Standard Model contributions. Present data permit \ncg to be the only source of \cpviol. Furthermore the most recent findings for g-2 of the muon are consistent with predictions from \ncg. If the geometry of space-time is \nc, $i.e.$ $[x_{\mu},x_{\nu}]=i \theta_{\mu \nu}$, then \nc \cpviolng effects may be manifest at low energies. For a \nc scale $\Lambda \equiv \theta^{-1/2} \leq 2 TeV$, \cpviol from \ncg is comparable to that from the Standard Model (SM) alone: the \nc contributions to $\epsilon$ and $\epsilon'/\epsilon$ in the K-system, may actually dominate over the Standard Model contributions. Present data permit \ncg to be the only source of \cpviol. Furthermore the most recent findings for g-2 of the muon are consistent with predictions from \ncg.Comment: fixed notation, corrected some typo