Hadrons as QCD Bound States

Bound state perturbation theory is well established for QED atoms. Today the hyperfine splitting of Positronium is known to 𝒪 (α7 log α). Whereas standard expansions of scattering amplitudes start from free states, bound states are expanded around eigenstates of the Hamiltonian including a binding potential. The eigenstate wave functions have all powers of α, requiring a choice in the ordering of the perturbative expansion. Temporal (A0 = 0) gauge permits an expansion starting from valence Fock states, bound by their instantaneous gauge field. This formulation is applicable in any frame and seems promising even for hadrons in QCD. The 𝒪(αs0) confining potential is determined (up to a universal scale) by a homogeneous solution of Gauss’ law.

Спектроскопическое исследование кристаллов KY-=SUB=-3-=/SUB=-F-=SUB=-10-=/SUB=-, активированных празеодимом

We report on the high-resolution Fourier spectroscopy study of KY3F10:Pr3+ crystals. The analysis of the transmission and luminescence spectra allowed us to refine and supplement the information on the crystal-field levels of the Pr3+ ion. The value of the hyperfine splitting of the ground state of Pr3+ in the KY3F10 cubic matrix is estimated. The observed shape of the spectral lines indicates the presence of defects in the sample under study.

Mass Spectrum and Decay Constants of Heavy Quarkonia

In this paper, a non-relativistic potential model is used to find the solution of radial Schrodinger wave equation by using Crank Nicolson discretization for heavy quarkonia ( ̅, ̅). After solving the Schrodinger radial wave equation, the mass spectrum and hyperfine splitting of heavy quarkonia are calculated with and without relativistic corrections. The root means square radii and decay constants for S and P states of c ̅ and ̅ mesons by using the realistic and simple harmonic oscillator wave functions. The calculated results of mass, hyperfine splitting, root means square radii and decay constants agreed with experimental and theoretically calculated results in the literature.

Direct observation of transitions between quantum states with energy differences below 10 neV employing a Sona unit

The direct access to atomic transitions between close by quantum states employing standard spectroscopic methods is often limited by the size of the necessary radio-frequency cavities. Here we report on a new tool for fundamental spectroscopy measurements that can overcome this shortcoming. For this, a Sona transition unit was used, i.e., two opposed solenoidal coils that provide an oscillating field in the rest frame of the through-going atomic beam. In this way, we were able to control the induced photon energy down to 10 neV or $$f \sim $$ f ∼ MHz. The tuneable parameter is the velocity of the atomic beam. For illustration of the method, we report a measurement of the hyperfine splitting energies between the substates with $$F=1$$ F = 1 and $$m_F = -1, 0, +1$$ m F = - 1 , 0 , + 1 of $$2S_{1/2}$$ 2 S 1 / 2 metastable hydrogen atoms as function of a magnetic field. Graphic Abstract