Shown in Fig. 2 (d) are the real and the imaginary parts of the D function versus the proton kinetic energy. Benjamins and van Dijk [13] used the hybrid Lee model with one compound state in each channel to de- scribe the nucleon-nucleon S -wave phase shifts below T$_{lab}$ = 500 MeV and to reproduce parameters related to the deuteron and the virtual $^{1}$S$_{0}$ state. The model does not have explicit CDD poles and primitives. However, it can be reformulated in terms of the QCB model with one CDD pole and two compound states that correspond to the primitive and a high-mass resonance [22]. Resonances and primitives do not exist as asymptotic states. In Feynman diagrams, propagators of primitives 1 / ( s − M 2 $_{α}$) are multiplied by form factors F ( s ). Such combinations do not have poles at s = M 2 $_{α}$. Primitives thus do not propagate, though they influence the dynam- ics. Summarizing, the physical meaning of the CDD poles was revisited. In the general case, the neighboring CDD poles squeeze masses of compound states related to bound states, resonances, or primitives. The primitives are P -matrix poles associated with zeros of the D func- tion on the unitary cut, which do not show up as poles of the S matrix. The Low scattering equation was gen- eralized for amplitudes with primitives. The primitive- type CDD poles occur in systems with repulsion. In the $^{3}$S$_{1}$ and $^{1}$S$_{0}$ nucleon-nucleon channels, the CDD poles at M = 3203 MeV and M = 2916 MeV are associated with the primitives at M$_{α}$ = 2047 MeV and M$_{α}$ = 2006 MeV, respectively. The model we used ensures that the D function has the correct analytical properties on the first Riemann sheet of the complex s plane and provides the partial wave amplitudes that satisfy the generalized Low scattering equation. The author is grateful to Yu. A. Simonov for help- ful discussions and I. M. Narodetsky for reading the manuscript and for useful remarks. This work is sup- ported by grant of Scientific Schools of Russian Federa- tion No. 4568.2008.2, RFBR grant No. 09-02-91341, and DFG grant No. 436 RUS 113/721/0-3. 4 In Figs. 2 (c,d), the real and the imaginary parts of the D functions vanish at s = s$_{p}$ . These are signatures of the primitives, along with crossing the levels δ ( s ) = 0 with negative slopes on Figs. 2 (a,b). The values of b and M$_{α}$ are close to those obtained in Refs. [5, 6]. FIG. 2: (Color online) $^{3}$S 1 and $^{1}$S 0 scattering phase shifts in radians (upper panel) and real and imaginary parts of the D functions (lower panel) versus the proton kinetic energy. The solid curves are parametrizations within the relativistic QCB model. The experimental phase shifts [21] are shown by triangles. 50 150 250 350 450 T$_{lab}$ [MeV] 0 1 2 3 $^{ }$(a) ($^{3}$S$_{1}$) T$_{lab}$ [MeV] 0.0 0.5 1.0 1.5 $^{ }$(b) ($^{1}$S$_{0}$) 50 150 250 350 450 -1500 -1000 -500 500 1000  -2 D(s) 2 1 -1 T$_{lab}$ [MeV] D(s) (c) -1500 -1000 -500 500 1000  -2 D(s) 2 1 -1 T$_{lab}$ [MeV] D(s) (d)