Calculation of the Longitudinal Structure Function from Regge-Like Behaviour of the Gluon Distribution Function in Leading Order Approximation at Low x

We present the calculations of FL longitudinal structure functions from DGLAP evolution equation in leading order (LO) at low-x, assuming the Regge-like behaviour of gluon distribution at this limit. The calculated results are compared with the H1 data and QCD fit. It is shown that the obtained results are very close to the mentioned methods. The proposed simple analytical relation for FL provides a t-evolution equation for the determination of the longitudinal structure function at low-x. All the results can consistently bedescribed within the framework of perturbative QCD, which essentially shows increases as x decreases.