Starting from π-N scattering amplitude and basing on the Mandelstam's representation and unitary condition, analyticity and threshold properties of fermion Regge trajectories of baryon quantum number 1 and strangeness 0 are investigated. The following preliminary results are obtained: (1) The position parameter of the Regge trajectories a(s) has a right-hand physical cut and no left-hand dynamical cut, but has a kinematical left-hand cut at s=0; (2) a(s) in the region s+(s) and α-(s), being of opposite space parity, are complex conjugate to each other. In the region 02, a±(s) are real but the dependence on s may be different; (3) The energy dependence of a(s) at the threshold is obtained; (4) Two kinds of Regge poles are distinguished. Those with a(W0)≠0 (W0-threshold energy) are responsible for dynamical resonances and bounded states. There are other kinds of the Regge trajectories for which a(W0)=0 and whose threshold behaviours are also investigated. As energy approaches the threshold from energy below the threshold, there are infinite pairs of poles approaching Re J=0 from the left half J-plane, each pair containing a couple of conjugate complex poles. While as energy approaches from above the threshold, there are also infinite pairs of poles approaching Re J=0, each pair containing poles in the first and third quadrant of the J-plane. For all these poles, Re α(s)→0 faster than Im a(s)→0 by one or two orders. The poles condense at the origin of the J-plane. We thus obtain the Gribov-Pomenranchuk condensation of the Regge poles in the case of Fermion trajectories. This kind of poles has a purely kinematical origin. They reflect the general properties of the S-matrix at the threshold.
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