Related papers: Muonium Hyperfine Splitting Uncertainty Revisited
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 differences are discussed between various next-to-leading order prescriptions for the QCD evolution of parton densities and structure functions. Their quantitative impact is understood to an accuracy of 0.02\%. The uncertainties due to…
We investigate the role of hyperfine mixing in the electromagnetic decay of ground state doubly heavy $bc$ baryons. As in the case of a previous calculation on $b\to c$ semileptonic decays of doubly heavy baryons, we find large corrections…
The contribution of pseudoscalar pole diagrams to the hadronic light-by-light corrections of order alpha^3 E_F to the ground state hyperfine splitting in hydrogenic atom is calculated in the pseudoscalar pole terms approximation. The vector…
Current measurements of isospin splittings in mesons and baryons are sufficiently precise that they allow estimates of the mass difference between constituent up and down quarks. Some previous results are updated in the light of these new…
In the framework of an extended bag model the magnetic moments, M1 transition moments, and decay widths of all ground-state heavy hadrons are calculated. For the heavy baryons containing three quarks of different flavors the effect of…
We calculate the next-to-leading order contribution to the masses of the heavy baryons in the bound state approach for baryons containing a heavy quark. These $1/N_C$ corrections arise when states of good spin and isospin are generated from…
In the $m_Q\rightarrow\infty$ limit, the hyperfine splittings in the ground state doubly heavy baryons $\left(QQq\right)$ and single heavy antimesons $(\bar{Q}q)$ are related by heavy quark-diquark symmetry (HQDQ) as the light degrees of…
The two-photon-annihilation contribution to the true muonium hyperfine splitting arising from $e$ and $\tau$ loops is obtained analytically at order $m_\mu\alpha^6$. The contribution to the hyperfine splitting is $-2.031092873…
The possibility of variations of the values of fundamental constants is a phenomenon predicted by a number of scenarios beyond General Relativity. This can happen if ``our'' fundamental constants are not the actual constants of the…
A new generation of parton distribution functions with increased precision and quantitative estimates of uncertainties is presented. This work includes a full treatment of available experimental correlated systematic errors for both new and…
We qualitatively corroborate the results of W. Roberts and M. Pervin in Int. J. Mod. Phys. A 24, 2401 (2009) according to which hyperfine mixing greatly affects the decay widths of $b\to c$ semileptonic decays involving doubly heavy $bc$…
Since nine years experiments have been observing a host of exotic states decaying into heavy quarkonia. The interpretation of most of them still remains uncertain and, in some cases, controversial, notwithstanding a considerable progress…
The ground state hyperfine splitting of positronium $\Delta_{\mathrm{HFS}}$ is sensitive to high order corrections of quantum electrodynamics (QED) in bound state. The theoretical prediction and the averaged experimental value for…
The status of coupling constant unification (with and without a unification of Yukawa couplings) is discussed. Uncertainties associated with the input coupling constants, $m_{b}$ and $m_{t}$, threshold corrections at the low and high scale,…
This paper aims at proving the fundamental role of a relativistic formulation for quarkonia models. We present a completely covariant description of a two-quark system interacting by the Cornell potential with a Breit term describing the…
Results are obtained for the decay rate of ortho and para states and for the hyperfine structure of the dimuonic system mu+ mu- (dimuonium). We calculate next--to-leading order radiative corrections. It is shown that previously reported…
It is argued that the heavy-quark limit of QCD requires a certain combination of hyperfine mass splittings in heavy-quark hybrid-meson multiplets to be unusually small. This observation will assist in the exploration of the heavy-quark…
We consider the hyperfine structure, the atomic spectrum and the decay channels of the bound mu+ mu- system (dimuonium). The annihilation lifetimes of low-lying atomic states of the system lie in the nanosecond range range. The decay rates…
Recent progress in quantum electrodynamics (QED) calculations of highly charged ions is reviewed. The theoretical predictions for the binding energies, the hyperfine splittings, and the g factors are presented and compared with available…