ISSN:
1434-6052
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract. The role playing by the “soft” ( $k_T 〈1$ GeV/c) region in the small- $x$ behaviour of $g_{1}(x,Q^2)$ and the non-singlet structure function $f_{1,NS}(x,Q^2)$ has been studied with the help of the effective QCD Lagrangian which takes into account the lightest degrees of freedom – the constituent quarks and the $\pi$ -mesons (Goldstone bosons). It has been shown that the quark-quark interaction due to the pion exchange has a negative coupling $g$ for the isovector component ( $I=1$ in the $t$ -channel) of $f_1(x,Q^2)$ and isosinglet component of $g_1(x,Q^2)$ . Here the pion induced interaction changes mainly the normalization of the quark distribution (it decreases $f_{1,NS}^{I=1}(x,Q^2)$ two times at $x 〈3 \cdot 10^{-3}$ ) and changes slightly the effective exponents $\lambda$ ( $f_{1,NS}$ , $g_1 \sim x^{-\lambda}$ at $x \rightarrow 0$ ). On the other hand due to a positive value of coupling $g$ the value of $\lambda$ increases by 15% for the isovector part of $g_1(x,Q^2)$ and up to $\lambda \approx 0.5$ (instead of $\lambda \approx 0.2$ without the pion contribution) for the isoscalar non-singlet structure function $f_{1,NS}^{I=0}(x,Q^2)$ .
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01245817
