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A description of the virtual photon absorption cross section difference sigma_{1/2}-sigma_{3/2} for the proton and the neutron is obtained with a parameterisation based on a Regge type approach. The parameterisation is obtained from global fits to the cross section data derived from the spin asymmetries measured in DIS of longitudinally polarised leptons from polarised ^1H, ^3He and ^2H targets in the range 0.3 GeV^2 < Q^2 < 70 GeV^2 and 4 GeV^2 < W^2 < 300 GeV^2. The fits give a reliable description of the data and provide predictions for the photo-production through a smooth Q^2-transition. The contribution above the resonance region to the Gerasimov-Drell-Hearn sum rule for real and virtual photons has been evaluated. For the real photons this contribution accounts for a large fraction of the discrepancy between the sum rule expectations and the single pion photo-production analysis estimates
We calculate moments of the $O(alpha_s^3)$ heavy flavor contributions to the Wilson coefficients of the structure function $F_2(x,Q^2)$ in the region $Q^2gg m^2$. The massive Wilson coefficients are obtained as convolutions of massive operator ma
Recently a few authors pointed out that the positroniums give rise to an extra contribution to the electron $g-2$ with the magnitude comparable to the $O(alpha^5)$ perturbative effect, which is not taken into account in the perturbative calculation u
We test the Gerasimov-Drell-Hearn (GDH) sum rule numerically by calculating the total photon absorption cross sections $sigma_{1/2}$ and $sigma_{3/2}$ on the nucleon via photon excitation of baryon resonances in the constituent quark model. A total o
Empirical formulas for the second inverse moment of the photoabsorption cross sections in nuclei are discussed in J. N. Orce, Phys. Rev. C 91, 064602 (2015). In this Comment I point out that the experimental values used are systematically too small i
We present measurements of the masses and decay widths of the baryonic states $Sigma_{c}(2455)^{0/++}$ and $Sigma_{c}(2520)^{0/++}$ using a data sample corresponding to an integrated luminosity of 711 fb$^{-1}$ collected with the Belle detector at th