The real part of the elementary electric gluon amplitude is given by where D $^{g}$( t ) stands for the gluon D - form factor (51). Finally, the real part of the magnetic gluon amplitude reads: The gluon D -form factor is defined according to where D $^{g}$( z, t ) stand for the gluon D -term for which the following Gegenbauer expansion was adopted in [3]: According to the analysis presented in [33, 37], the real part of the elementary amplitude A g ( E ) can be expressed through its imaginary part with the help a dispersion relation with one subtraction in the variable ω = 1 ξ for the fixed value of t : 17 A g ( E $^{)}$( ξ, t ) = 2 D $^{g}$( t ) + 1 π ∫ 1 0 $_{dξ}$′ ( 1 ξ − ξ ′ − iϵ − 1 ξ + ξ ′ − iϵ ) Im A g ( E $^{)}$( $_{ξ}$′ − iϵ, t ) . (53) D $^{g}$( z, t ) = 3 4 (1 − z $^{2}$)2 [ d g $_{1}$( t ) + d g $_{3}$( t ) C$^{5}$ 2 ( z ) + d g $_{5}$( t ) C$^{5}$ 2 4 ( z ) + ... ] . (52) D $^{g}$( t ) = ∞ ∑ n =1 odd d g $_{n}$( t ) = ∫ 1 − 1 dz 1 1 − z $_{2}$D $^{g}$( z, t ) , (51) Re A g ( M $^{)}$( ξ, t ) = − 2 3 ∫ 1$_{−}$ √ 1$_{−}$ ξ 2 ξ 0 $_{dx}$√$_{1 +}$ x 2   1 √ 1 + x 2 − 2 x ξ + 1 √ 1 + x 2 + 2 x ξ − 2 √$_{1 +}$ x 2   × ∂ ∂x ( √$_{1 +}$ x 2 1 − x 2 N g ( M $^{)}$( x, t ) ) − 2 3 ∫ 1 1$_{−}$ √ 1$_{−}$ ξ 2 ξ $_{dx}$√$_{1 +}$ x 2   1 √ 1 + x 2 − 2 x ξ − 2 √$_{1 +}$ x 2   ∂ ∂x ( √$_{1 +}$ x 2 1 − x 2 N g ( M $^{)}$( x, t ) ) . (50) Re A g ( E $^{)}$( ξ, t ) = 2 3 ∫ 1$_{−}$ √ 1$_{−}$ ξ 2 ξ 0 dx x N g ( E $^{)}$( x, t ) × [ 1 √ 1 − 2 x ξ + x 2 + 1 √ 1 + 2 x ξ + x 2 − 2 √$_{1 +}$ x 2 ] + 2 3 ∫ 1 1$_{−}$ √ 1$_{−}$ ξ 2 ξ dx x N g ( E $^{)}$( x, t ) [ 1 √ 1 + 2 x ξ + x 2 − 2 √$_{1 +}$ x 2 ] + 2(1 − τ ) D $^{g}$( t ) , (49)