The sum rule for the structure functions of the deuteron from the current algebra on the null-plane

The fixed-mass sum rules for the deuteron target have been derived by using the connected matrix element of the current anti-commutation relation on the null-plane. From these sum rules we obtain the relation between the pseudo-scalar meson deuteron total cross sections and the structure functions of the deuteron. We show that the nuclear effect on the mean hypercharge of the sea quark of the proton can be studied by this relation. Further we obtain the relation among the Born term, the resonances and the non-resonant background in the small $Q^2$ region, and as a new aspect of the spin 1 target, explicit relation of the tensor structure function $b_2$ at small or moderate $Q^2$ to that at large $Q^2$.Comment: 17pages, 1figur

The constraint on the spin dependent structure function g1g_1 at low Q2Q^2 through the sum rule corresponding to the moment at n=0n=0

The sum rules for the spin dependent structure function $g_1^{ab}$ in the null-plane formalism corresponding to the moment at $n=0$ has been transformed to the sum rule which relates the $g_1^{ab}$ with the cross section of the isovector photon or the real photon. Based on these sum rules, we argue that there is a deep connection among the elastic, the resonance, and the non-resonant contributions, and that it explains why the sign of the generalized Gerasimov-Drell-Hearn sum changes at very small $Q^2$.Comment: 4pages,Talk presented at SPIN2006, October 2-7, 2006, Kyoto, Japa

Soft pions at high energy as an origin of flavor asymmetry of the light sea quarks in the nucleon

By using the soft pion theorem in the inclusive reactions, soft pions' contribution to the structure function $F_2$ in the nucleon is estimated. It is shown that this contribution produces such a large flavor asymmetry in the light sea quark distributions that it gives about $30\sim 50$ of the NMC deficit in the Gottfried sum.Comment: 9 pages, 2 figures, to be published in the Prog.Theor.Phy

Flavor Asymmetry of the Sea Quarks in the Baryon Octet

We show that the chiral $SU(n)\otimes SU(n)$ flavor symmetry on the null-plane severely restricts the sea quarks in the baryon octet. It predicts large asymmetry for the light sea quarks $(u,d,s)$, and universality and abundance for the heavy sea quarks. Further it is shown that existence of the heavy sea quarks constrained by the same symmetry reduces the theoretical value of the Ellis-Jaffe sum rule substantially.Comment: 19 pages,Late

Symmetry restoration of the soft pion corrections for the light sea quark distributions in the small xx region

The soft pion correction at high energy may play a crucial role in non-perturbative parts of sea quark distributions. In this paper, we show that, while the soft pion correction for the strange sea qaurk distribution is suppressed in the large and the medium $x$ region compared with that for the up and the down sea quark one, it can become large and SU(3) flavor symmetric in the very small $x$ region. This gives us a good reason for the symmetry restoration of light sea quark distributions required by the mean charge sum rule for the light sea quarks. Then, by estimating this sum rule with the help of the results obtained by the soft pion correction, it is argued that there is a large symmetry restoration of the strange sea quark in the region from $x=10^{-2}$ to $10^{-6}$ at $Q^2\sim 1$ GeV.Comment: 22 pages including 4 eps figures, ReVTeX, to appear in Phys. Rev.