Related papers: The Proton Radius Puzzle
While measurements of the hyperfine structure of hydrogen-like atoms are traditionally regarded as test of bound-state QED, we assume that theoretical QED predictions are accurate and discuss the information about the electromagnetic…
Precise measurements of the mass and width of the W boson are sensitive to radiative corrections and can be used to place limits on new physics beyond the Standard Model and validate the consistency of the model. In particular, the W boson…
The proton is a fundamental constituent of matter. It is an extended object with finite size that can be inferred with some degree of accuracy from several measurements. Using constraints from the analytic behavior of the form factors we…
A phenomenological extraction of pressure within the proton has recently been performed using JLab CLAS data (arXiv:2104.02031 [nucl-ex]). The extraction used a 3-dimensional Breit frame description in which the initial and final proton…
Fundamental physics could be described as having a muon problem. Discrepancies between theory and experiment in a number of muonic measurements ($r_P$, $a_\mu$, $H\rightarrow\mu\tau$, $\mathcal{R}_K$, $\mathcal{R}_{D^*}$) have been observed…
This is a brief review of the status of understanding the proton polarizabilities in chiral perturbation theory and of their relevance to the `proton charge radius puzzle'.
Recent measurements of the Lamb shift of muonic helium-4 ions were used to infer the alpha particle charge radius. The value found is compatible with the radius extracted from the analysis of the electron-helium scattering. Thus, the new…
Measurements of the difference between the squared charge radii of the helion ($^3$He nucleus) and the $\alpha$-particle ($^4$He nucleus) have been characterized by longstanding tensions, recently spotlighted in the 3.6 $\sigma$ discrepancy…
The first determination of the nuclear charge radius by laser spectroscopy for a five-electron system is reported. This is achieved by combining high-accuracy ab initio mass-shift calculations and a high-resolution measurement of the…
A recent proposal to measure the proton form factor by means of muon-proton scattering will use muons which are not ultrarelativistic (and also not nonrelativistic). The usual equations describing the scattering cross section use the…
The rms-radius $R$ of the proton charge distribution is a fundamental quantity needed for precision physics. This radius, traditionally determined from elastic electron-proton scattering via the slope of the Sachs form factor $G_e(q^2)$…
We show that off-mass-shell effects arising from the internal structure of the proton provide a new proton polarization mechanism in the Lamb shift, proportional to the lepton mass to the fourth power. This effect is capable of resolving…
The angular distribution of the differential cross sections for proton elastic scattering from $^{132}$Sn at 196-210 MeV/nucleon was successfully measured over a momentum transfer range of 0.80 to 2.1 fm$^{-1}$. Using a relativistic impulse…
We investigate the feasibility of measuring the proton charge radius through dimuon photoproduction off a proton target. Our findings indicate that the Bethe-Heitler mechanism, which dominates at small momentum transfers, allows for an…
A precision measurement by AMS of the antiproton-to-proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV is presented based on $3.49\times10^5$ antiproton events and $2.42\times10^9$ proton events. Above…
The standard definition of the electromagnetic radius of a charged particle (in particular the proton) is ambiguous once electromagnetic corrections are considered. We argue that a natural definition can be given within an effective field…
By combining a renormalization group argument relating the charge e and mass m of the proton by e^2 ln m ~ 0.1 pi (in Planck units) with the Carter-Carr-Rees anthropic argument that gives an independent approximate relation m ~ e^20 between…
Proton radioactivity has been investigated using the effective liquid drop model with varying mass asymmetry shape and effective inertial coefficient. An effective nuclear radius constant formula replaces the old empirical one in the…
The goal of the FAMU experiment at RIKEN RAL is the measure of the hyperfine splitting of the ground state of the muonic hydrogen, to allow a determination of the proton Zemach radius with a precision better than $5 \times 10^{-3}$ . The…
We discuss recent suggestions on the resolution of the proton radius puzzle put forward in [1,2] and discovery of a nonperturbative quantum-electrodynamic contribution of order $(\alpha/\pi)^5$ to lepton anomalous magnetic moments announced…