Cross sections for pentaquark baryon production from protons in reactions induced by hadrons and photons

Using hadronic Lagrangians that include the interaction of pentaquark ${\Theta }^{+}$ baryon with $K$ and $N$, we evaluate the cross sections for its production from meson-proton, proton-proton, and photon-proton reactions near threshold. With empirical coupling constants and form factors, the predicted cross sections are about $1.5\text{mb}$ in kaon-proton reactions, $0.1\text{mb}$ in $\rho$-nucleon reactions, $0.05\text{mb}$ in pion-nucleon reactions, $20\mu \mathrm{b}$ in proton-proton reactions, and $40\text{nb}$ in photon-proton reactions.

Figure 1

Diagrams for ${\Theta }^{+}$ production from meson-nucleon reactions.

Figure 2

Spin and isospin averaged cross sections for ${\Theta }^{+}$ production from meson-nucleon reactions as functions of center-of-mass energy: $\pi N\to \overline{K}\Theta$ (solid curve), $KN\to \pi \Theta$ (dashed curve), and $\rho N\to \overline{K}\Theta$ (dotted curve).

Figure 3

Diagrams for $\Theta$ production from proton-proton reactions.

Figure 4

Cross sections for ${\Theta }^{+}$ production from proton-proton reactions $pp\to {\Sigma }^{+}{\Theta }^{+}$ (dashed curve), $pp\to {\pi }^{+}\Lambda {\Theta }^{+}$ (dotted curve), and $pp\to {\overline{K}}^{0}p{\Theta }^{+}$ (dash-dotted curve) functions of center-of-mass energy. The total cross section is given by solid curve.

Figure 5

Diagrams for ${\Theta }^{+}$ production from photon-proton reactions with two-body final state.

Figure 6

Diagrams for ${\Theta }^{+}$ production from photon-proton reactions with three-body final states.

Figure 7

Cross sections for ${\Theta }^{+}$ production from photon-proton reactions as functions of center-of-mass energy: total (solid curve), $\gamma p\to {\overline{K}}^0{\Theta }^{+}$ (dashed curve), $\gamma p\to K^{*-}{\pi }^{+}{\Theta }^{+}$ (dotted curve), and $\gamma p\to K^{-}{\rho }^{+}{\Theta }^{+}$ (dash-dotted curve).