We calculate the Schiff moment of the nucleus 199 Hg, created by πNN vertices that are odd under parity (P) and time-reversal (T). Our approach, formulated in diagrammatic perturbation theory with important core-polarization diagrams summed to all orders, gives a close approximation to the expectation value of the Schiff operator in the odd-A Hartree-Fock-Bogoliubov ground state generated by a Skyrme interaction and a weak P-and T-odd pion-exchange potential. To assess the uncertainty in the results, we carry out the calculation with several Skyrme interactions, the quality of which we test by checking predictions for the isoscalar-E1 strength distribution in 208 Pb, and estimate most of the important diagrams we omit.
We use the Skyrme-Hartree-Fock method, allowing all symmetries to be broken, to calculate the timereversal-violating nuclear Schiff moment ͑which induces atomic electric dipole moments͒ in the octupoledeformed nucleus 225 Ra. Our calculation includes several effects neglected in an earlier work, including self-consistency and polarization of the core by the last nucleon. We confirm that the Schiff moment is large compared to those of reflection-symmetric nuclei, though ours is generally a few times smaller than recent estimates. 1 The statement that the nucleus has octupole and quadrupole deformation really refers to its intrinsic state, a concept we elaborate on below, and does not contradict its insensitivity to applied electric fields with multipolarity greater than one. PHYSICAL REVIEW C
Estimating functions provide a very general framework for statistical inference, and are particularly useful when one is either unable or unwilling to specify a likelihood function. This paper aims to provide an accessible review of estimating function theory that has potential for application to the analysis and modelling of a wide range of complex systems. Assumptions are given in terms that can be checked relatively easily in practice, and some of the more technical derivations are relegated to an online supplement for clarity of exposition. The special case of the generalized method of moments is considered in some detail. The main points are illustrated by considering the problem of inference for a class of stochastic rainfall models based on point processes, with simulations used to demonstrate the performance of the methods.
The theoretical properties of the Whittle likelihood have been studied extensively for many different types of process. In applications however, the utility of the approach is limited by the fact that the asymptotic sampling distribution of the estimator typically depends on third‐order and fourth‐order properties of the process that may be difficult to obtain. In this article, we show how the methodology can be embedded in the standard framework of estimating functions, which allows the asymptotic distribution to be estimated empirically without calculating higher‐order spectra. We also demonstrate that some aspects of the inference, such as the calculation of confidence regions for the entire parameter vector, can be inaccurate but that a small adjustment, designed for application in situations where a mis‐specified likelihood is used for inference, can lead to marked improvements.
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