content_image/328685.jpg content_image/328684.jpg content_image/328683.jpg content_image/328682.jpg content_image/328680.jpg content_image/328681.jpg content_image/328679.jpg content_image/328678.jpg content_image/328677.jpg
From these conditions we fix completely the two parameters to α = − 1 and β = 0 so that the mass function (in the y ≤ 0 region ) becomes: 

<img src='content_image/328685.jpg'>

The most general condition that we can impose on the term multiplying to 1 / [ y (1 − y )] in order that the equation be that of the hypergeometric function is that it be equal to a constant γ . Therefore we get three equations: 

<img src='content_image/328684.jpg'>

<img src='content_image/328683.jpg'>

<img src='content_image/328682.jpg'>

From Eq. (16a), it is possible to solve for µ while λ is found summing Eq. (16b) and Eq. (16c). We obtain finally: 

<img src='content_image/328680.jpg'>

<img src='content_image/328681.jpg'>

<img src='content_image/328679.jpg'>

having defined ν = ik/a where k 2 = E 2 − m 2 $_{0}$. Our Eq. (13) becomes the differential equation of the hypergeometric function 

<img src='content_image/328678.jpg'>

and the general solution is (with D$_{1}$ and D$_{2}$ constants): 

<img src='content_image/328677.jpg'>

