QCD predictions for spin dependent photonic structure function $g_1^{\gamma}(x,Q^2)$ in the low x region of future linear colliders

Abstract

Spin dependent structure function $g_1^{\gamma}(x,Q^2)$ of the polarised photon is analysed within the formalism based upon the unintegrated spin dependent parton distributions incorporating the LO Altarelli-Parisi evolution and the double $ln^2(1/x)$ resummation at low values of Bjorken parameter x. We analyse the effects of the double $ln^2(1/x)$ resummation on the behaviour of $g_1^{\gamma}(x,Q^2)$ in the low x region which may be accessible in future linear $e^+e^-$ and $e\gamma$ colliders. Sensitivity of the predictions on the possible nonperturbative gluon content of the polarised photons is analysed. Predictions for spin dependent gluon distribution $\Delta g^{\gamma} (x,Q^2)$ are also given.