Related papers: Two-Loop Electron Factor Contribution to Lamb Shif…
The radiative self-energy correction to the bound-electron g factor of 2P_1/2 and 2P_3/2 states in one-electron ions is evaluated to order alpha (Z alpha)^2. The contribution of high-energy virtual photons is treated by means of an…
Two corrections to the Lamb shift, induced by the polarization operator insertions in the external photon lines are calculated.
The pion electromagnetic form factor is calculated at lower and higher momentum transfer in order to explore constituent quark models and the differences among those models. In particular, the light-front constituent quark model is utilized…
The hyperfine structure (hfs) and the g factor of a bound electron are caused by external magnetic fields. For the hfs, the magnetic field is due to the nuclear spin. A uniform-in-space and constant-in-time magnetic field is used to probe…
We present the dispersion relation approach based on unitarity and analyticity to evaluate the two-photon exchange contribution to elastic electron-proton scattering. The leading elastic and first inelastic $\pi N$ intermediate state…
Currently, both the g factor measurement of the muon as well as the Lamb shift 2S-2P measurement in muonic hydrogen are in disagreement with theory. Here, we investigate possible theoretical explanations, including proton structure effects…
A formula for the electron spin relaxation rate of an electron-phonon system is derived using a new spring-loop diagram method. The result contains the distribution functions for the electrons and phonons properly. Therefore, all the spin…
We argue that the proton's charge-radius contributes differently to shifts of Hydrogen-like energy levels than naively expected due to an incorrect choice for the boundary condition at the proton's position in standard calculations. In…
The two-loop electron self-energy correction is one of the most problematic QED effects and, for a long time, was the dominant source of uncertainty in the theoretical prediction of the bound-electron $g$ factor in hydrogen-like ions. A…
Two-loop self-energy corrections to the bound-electron $g$ factor are investigated theoretically to all orders in the nuclear binding strength parameter $Z\alpha$. The separation of divergences is performed by dimensional regularization,…
Two-photon exchange contributions have potentially broad ranging impact on several charged lepton scattering measurements. Previously believed to be extremely small, based in part on comparisons of positron scattering and electron…
We review the theory of the Lamb shift for muonium, provide an updated numerical value and present the prospects of the Mu-MASS collaboration at PSI to improve upon their recent measurement. Due to its smaller nuclear mass, the…
Long-range forces between macroscopic objects are mediated by light particles that interact with the electrons or nucleons, and include spin-dependent static components as well as spin- and velocity-dependent components. We parametrize the…
We analyze the electromagnetic pion and kaon form factor by including radiative and higher-twist effects within the framework of resummed pQCD in the space-like region. We focus on the transition from the perturbative to non-perturbative…
It has been suggested that two-photon exchange corrections could explain the discrepancy between Rosenbluth extractions of the proton form factors and recent polarization transfer measurements. We propose a precise comparison of…
The recently proposed MUonE experiment at CERN aims at providing a novel determination of the leading order hadronic contribution to the muon anomalous magnetic moment through the study of elastic muon-electron scattering at relatively…
We revise the radiative corrections to double-Dalitz decays ($P\to\ell\bar{\ell}\ell'\bar{\ell}'$), completing the full next-to-leading order calculation in QED as compared to existing calculations. As a result, we find mild differences…
We report calculations of QED corrections to the $g$ factor of Li-like ions induced by the exchange of two virtual photons between the electrons. The calculations are performed within QED theory to all orders in the nuclear binding strength…
New corrections to the energy of $S$-levels of positronium of order $m\alpha^6$ which are as large as several hundred kilohertz are obtained. A new recoil correction of order $\alpha(Z\alpha)^5(m/M)m$ to the Lamb shift in hydrogen is…
We compute corrections to the gyromagnetic factor of an electron bound in a hydrogen-like ion at order alpha^2(Z alpha)^5. This result removes a major uncertainty in predictions for silicon and carbon ions, used to determine the atomic mass…