Scaling Behavior of the Ratio of Longitudinal to Transverse Total Virtual-Photoabsorption Cross Sections

The Bjorken scaling of $R=\frac{{\sigma }_L}{{\sigma }_T}$ is studied. We show that the ratio $\frac{{\nu }^{2}R}{M^2{Q}^2}$ [which scales in canonical spin-(½) theories] behaves as $\frac{1}{x^2}$ ($x=+\frac{Q^2}{2\nu }$) for small $x$ and as ${\mathrm{}(1-x)\mathrm{}}^{-\alpha }$ ($0<\mathrm{}\alpha <2\mathrm{}$) for $x$ near unity. We compare the scaling of $\nu W_2$ as extracted from the differential cross-section data using this form of $R$ with that of $\nu W_2$ extracted using a form of $R$ appropriate when some charged spin-0 constituents are present.