t dependence of the slope of the high energy elastic pp cross section

We consider the main factors which cause the variation of the value of the local slope of the elastic pp cross section B(t)=d[\ln(d\sigma_el(pp)/dt]/dt with t. Namely, we discuss the role of the pion-loop insertion in the pomeron trajectory, the t-dependence of the pomeron-nucleon coupling and the role of the eikonalization of the proton-proton amplitude in both the one- and two-channel eikonal models.