We present a high-precision calculation of the recoil--finite-size correction to hyperfine splitting (HFS) in muonic and electronic hydrogen based on nucleon electromagnetic form factors obtained from dispersion theory. This will help guide upcoming searches HFS transition hydrogen, allow precise determination polarizability Zemach radius contributions when this is found.

The current measurement of muonic g− 2 disagrees with the theoretical calculation by about 3 standard deviations. Hadronic vacuum polarization (HVP) and hadronic light by light (HLbL) are the two types of processes that contribute most to the theoretical uncertainty. The current value for HLbL is still given by models. I will describe results from a first-principles lattice calculation with a 1...

Considering that gravitational force might deviate from Newton’s inverse-square law (ISL) and become much stronger in small scale, we propose a kind of optical spectroscopy experiment to detect this possible deviation and take electronic, muonic and tauonic hydrogen atoms as examples. This experiment might be used to indirectly detect the deviation of ISL down to nanometer scale and to explore ...

We report a new measurement of the ratio h/mRb between the Planck constant and the mass of Rb atom. A new value of the fine structure constant is deduced, α = 137.035 999 037 (91) with a relative uncertainty of 6.6 × 10. Using this determination, we obtain a theoretical value of the electron anomaly ae = 0.001 159 652 181 13(84) which is in agreement with the experimental measurement of Gabriel...

The sixth-order electron-loop vacuum-polarization contribution to the 2P1/2 − 2S1/2 Lamb shift of the muonic hydrogen (μ−p+ bound state) has been evaluated numerically. Our result is 0.005295 (1) meV. This eliminates the largest uncertainty in the theoretical calculation. Combined with the proposed precision measurement of the Lamb shift it will lead to a very precise determination of the proto...

The bb̄ production cross section in 920 GeV proton-nucleus fixed target collisions is measured by observing double muonic decays of b-flavoured hadrons in the kinematic region −0.3 < xF(μ) < 0.15. A total number of 76 ± 12 bb̄ events is obtained with a likelihood fit of the signal and background simulated events to the data. The resulting cross section is σbb̄ = 16.2 ± 2.5stat ± 2.8sys nb/nucleon,...

The sixth-order electron-loop vacuum-polarization contribution to the 2P1/2 − 2S1/2 Lamb shift of the muonic hydrogen (μ−p+ bound state) has been evaluated numerically. Our result is 0.005295 (1) meV. This eliminates the largest uncertainty in the theoretical calculation. Combined with the proposed precision measurement of the Lamb shift it will lead to a very precise determination of the proto...

The Pierre Auger Observatory allows the measurement of both longitudinal profiles and lateral particle distributions of high-energy showers. The former trace the overall shower development, mainly of the electromagnetic component close to the core where the latter reflect the particle densities in the tail of the shower far away from the core and are sensitive to both the muonic and electromagn...