Related papers: The Proton Radius Puzzle
The successful precision measurement of the rate of muon capture on a proton by the MuCap Collaboration allows for a stringent test of the current theoretical understanding of this process. Chiral perturbation theory, which is a low-energy…
We have determined the proton and the neutron charge radii from a global analysis of the proton and the neutron elastic form factors, after first performing a flavor decomposition of these form factors under charge symmetry in the light…
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…
The question of the determination of the proton charge radius $R_p$ from electron scattering data led to an unprecedented experimental effort for measurements of the electric form factor of the proton at low and very low momentum transfer…
Extracting the proton charge radius from electron scattering data requires determining the slope of the charge form factor at $Q^2$ of zero. But as experimental data never reach that limit, numerous methods for making the extraction have…
In this paper I review a number of recent results in the field of exotic atoms. Recent experiments or ongoing experiments with muonic, pionic and antiprotonic hydrogen, as well as recent measurement of the pion mass are described. These…
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…
The PRad experiment has credibly demonstrated the advantages of the calorimetric method in e-p scattering experiments to measure the proton root-mean-square (RMS) charge radius with high accuracy. The PRad result, within its experimental…
To extract the charge radius of the proton, $r_{p}$, from the electron scattering data, the PRad collaboration at Jefferson Lab has developed a rigorous framework for finding the best functional forms - the fitters - for a robust extraction…
Ground-state hyperfine splittings in hydrogen and muonium are very well measured. Their difference, after correcting for magnetic moment and reduced mass effects, is due solely to proton structure--the large QED contributions for a…
Since the announcement of the proton spin crisis by the European Muon Collaboration there has been considerable progress in unravelling the distribution of spin and orbital angular momentum within the proton. We review the current status of…
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 $G_e(q^2)$…
The proton-neutron interaction is investigated by solving the Schrodinger equation, where a Yukawa type of potential with one pion exchanging between the proton and the neutron is assumed. Since the deutron is the unique bound state of the…
The "proton size puzzle" and the "muon anomalous moment problem" are incomplete descriptions of significant discrepancies of Standard Model calculations with experiments. What is particularly new is that the experiments and theory confront…
As it involves the lightest physical states excited from the vacuum by the vector quark current, near-threshold $\rho^0$ photoproduction is considered a possible way to research the proton radius and the absolute value of the scattering…
A new method is proposed to deduce the neutron radii of neutron-rich nuclei. This method requires measuring the reaction cross sections of both the neutron-rich nucleus and its stable isotope at the same energy on a proton target. Using…
Newly calculated bounds on the strength of the coupling of an electron to a proton or a neutron by a fifth force are presented. These results are derived from the high precision spectroscopic data currently available for hydrogen,…
The radiative muon capture(RMC) on a proton is analyzed by means of heavy baryon chiral perturbation theory. The emitted photon energy spectrum is calculated and compared with the experimental data by taking the spin sum on the muonic atom…
To comply with the critique of the Comment [J. Arrington, arXiv:1602.01461], we consider another modification of the proton electric form factor, which resolves the "proton-radius puzzle". The proposed modification satisfies all the…
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…