In a paper says that the limit when [tex]\alpha \to 0[/tex] with [tex]

[alejandrito29]

In a paper says that the limit when \alpha \to 0 with \sigma = \pm 1 of:

\frac{1}{4 \alpha}(1 + \sigma \sqrt{1 - \frac{8}{l^2} \alpha } )

has a well defined limit only when \sigma = - 1,

¿why??...I don't understand

 

[disregardthat]

Well, calculate the limit for sigma = -1, and see what happens when sigma = 1 (try to calculate it).