Related papers: Constraints on proton structure from precision ato…
Production of electroweak bosons, heavy quarks and jets in proton-proton collisions probe different aspects of QCD and are sensitive to the details of proton structure, expressed by parton distribution functions (PDFs). Precise measurements…
The FAMU experiment aims at an indirect measurement of the Zemach radius of the proton. The measurement is carried out on muonic hydrogen atoms produced through the low-momentum (50-60 MeV/c) muon beam a the RIKEN-RAL negative muon…
Laser spectroscopy of muonic atoms has been recently used to probe properties of light nuclei with unprecedented precision. We introduce nuclear effects in hydrogen-like atoms, nucleon structure quantities (form factors, structure…
The rate of nuclear muon capture by the proton has been measured using a new experimental technique based on a time projection chamber operating in ultra-clean, deuterium-depleted hydrogen gas at 1 MPa pressure. The capture rate was…
Understanding the internal structure of the proton-including its mass spectrum, electromagnetic and gravitational form factors, and mechanical properties-remains a central challenge in hadronic physics. While lattice QCD and experimental…
Recently, the charge radius of the proton was extracted for the first time from muonic hydrogen. The value obtained is five standard deviations away from similar measurements of regular hydrogen. This talk discusses work done in…
The muonium atom is the purely leptonic bound state of a positive muon and an electron. It has a lifetime of 2.2 $\mu$s. The absence of any known internal structure provides for precision experiments to test fundamental physics theories and…
The proton diffractive structure function $F_2^{D(3)}$ measured in the H1 and ZEUS experiments at HERA is analyzed in terms of both Regge phenomenology and perturbative QCD evolution. A new method determines the values of the Regge…
Recent recoil polarization measurements in Hall A at Jefferson Lab show that the ratio of the electric to magnetic form factors for the proton decreases significantly with increasing Q^2. This contradicts previous Rosenbluth measurements…
Nucleon properties are modified in the nuclear medium. To understand these modifications and their origin is a central issue in nuclear physics. For example, a wide variety of QCD-based models, including quark-meson coupling and…
The increasing precision of the measurements on the proton structure and an improved treatment of the correlated systematic experimental errors constitute a major step forward in our understanding of the flavour decomposition of the proton…
The proton radius puzzle, i.e. the large discrepancy in the extraction of the proton charge radius between regular and muonic hydrogen, challenges our understanding of the structure of the proton. It can also be an indication of a new force…
The proton radius puzzle questions the self-consistency of theory and experiment in light muonic and electronic bound systems. Here, we summarize the current status of virtual particle models as well as Lorentz-violating models that have…
The proton radius puzzle, the discrepancy between the proton radius measured in muonic hydrogen and electronic hydrogen, has yet to be resolved. There are suggestions that beyond the standard model (BSM) physics could resolve both this…
The calculation of hadronic polarizability contribution of the nucleus to hyperfine structure of muonic hydrogen and helium is carried out within the unitary isobar model and experimental data on the polarized structure functions of deep…
We present a new independent evaluation of the hadronic and QCD contributions to the QED running coupling \alpha(M_Z) and to the muonium hyperfine splitting \nu. We obtain: \Delta\alpha_{had}=2770(17)10^{-5} and \Delta\nu_{had}=232.5(2.5)…
There is a long-standing discrepancy between different measurements of the electric and magnetic radii of the proton. Lattice QCD calculations are a well-suited tool for theoretical investigations of the structure of the nucleon from first…
Constructive resonances with minimum entropy are derived from measurements of photoelectric effect cross sections at atomic K-shell thresholds. A resonance region with optimal constructive interference is given by a principal wave length…
Stationary target measurements of the nucleon form factors have been performed with high precision down to $Q^2$ of $\sim$ 0.01 GeV$^2$ for protons ($G_E^p$) and down to $\sim$ 0.1 GeV$^2$ for neutrons ($G_M^n$). Conventional extraction…
The fully relativistic theory of the Zeeman splitting of the $(1s)^2 2s$ hyperfine-structure levels in lithiumlike ions with $Z=6 - 32$ is considered for the magnetic field magnitude in the range from 1 to 10 T. The second-order corrections…