# In a paper says that the limit when $$\alpha \to 0$$ with $$## Main Question or Discussion Point In a paper says that the limit when [tex]\alpha \to 0$$ 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