Comment on “On the Barut-Vigier model of the hydrogen atom” by Samsonenko et al.

Contrary to the claim of Samsonenko, Tahti and Ndahayo [Phys. Lett. A 220 (1996) 297], it is found that the ground state energy for a hydrogen atom in the Barut-Vigier potential is E = 13.6 eV.     

Comment on “On the quantum Zeno effect” by Nakazato et al.

Recently, using a specific example involving neutron spin, Nakazato et al. [Phys. Lett A 199 (1995) 27] argued that the uncertainty principle would impose a remarkable limitation on the mathematical limit involved in the quantum Zeno effect. In this paper we show that it is impossible for Nakazato et al. to obtain this limitation by the uncertainty relation, because an unsuitable assumption has been used in their deduction process.     

Reply to the Comment by A.W. Thomas et al. on “The role of the orbital angular momentum in the proton spin”

The orbital angular momenta L^u and L^d of up- and down-quarks in the proton are estimated as functions of the energy scale as model independently as possible on the basis of Ji's angular-momentum sum rule. This analysis indicates that L ^u - L ^d is large and negative even at the low energy scale of nonperturbative QCD, in contrast to Thomas' similar analysis based on the refined cloudy bag model. We pursuit the origin of this apparent discrepancy and suggest that it may have a connection with the fundamental question of how to define quark orbital angular momenta in QCD.