Determination of the values of fundamental physical constants and precision tests of quantum electrodynamics

• Applicant: Savely Karshenboim, Ph.D.
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas ; Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2017 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 346672842

The project is targeting evaluation of precision world data to perform QED tests, to determine the values of the fundamental constants, and to search for new physics. I consider the project as a part of a long-term program. In this sense the objectives for the continuation of the project do not change too much; the current state of the art includes now a part of the preliminary report on the previous stage of the program, realized within the previous project. The work program contains the same generic parts, but it is now focused on other elements. A part of the work has been done within the CODATA task group on fundamental constants, but the ultimate purpose is to perform a separate overall least-square evaluation. The work in both directions (within the task group and beyond it) will be continued. Fundamental constants and their numerical values play an important role in physics. Sometimes those constants are accessible directly, sometimes we have to consider an atomic system, properties of which are calculable in the terms of fundamental constants. Certain physical constants can be determined with a high accuracy by few methods. Consistency of those results proves the reliability of theoretical and experimental methods applied. In particular, a comparison of the results obtained by different methods is a severe test of bound state quantum electrodynamics (QED). While QED for free particles is well established, the adaptation of QED to the bound-state problems is not an easy issue. Many different sectors of QED are involved into precision determination of fundamental constants. An evaluation of the world data on the subject may set a constraint on new physics. It is not necessary, that the most accurate experiments are the most sensitive to the new physics. In the meanwhile, the evaluation of the world data to obtain the best values of the fundamental constants regularly performed under auspice of the CODATA task group, being focused on the most accurate experiments, ignores a part of data, important to test bound-state QED.I plan to perform a multivariate analysis of the correlated world data, for which I consider to make a number of significant differences comparing to the existing procedure:- an independent data selection focused on accuracy of the data and on their sensitivity to QED contributions and to new physics;- a re-estimation anew of QED uncertainties, which is not always satisfactory;- a re-estimate of the uncertainty of evaluation of the data, which have been used through the compilations;- additional evaluations to be run to look for new physics;- inclusion of various theoretical data (such as numerical results on medium Z or results of lattice calculations) as pseudodata. For critical sectors of data I consider to perform separate least-square evaluations. Eventually it should be an independent check of consistency of the QED-related data and of the CODATA recommended values of fundamental constants.

• DFG Programme: Research Grants
• International Connection: Russia
• Cooperation Partner: Professor Simon Eidelman, Ph.D., until 3/2022