Coupling constant for $Λ(1405)\bar{K}N$

The value of the $Λ(1405){\bar K}N$ coupling constant $g_{Λ(1405)\bar{K}N}$ is obtained by fitting it to the experimental data on the total cross sections of the $K^-p \to π^0Σ^0$ reaction. On the basis of an effective Lagrangian approach and isobar model, we show that the value $|g_{Λ(1405)\bar{K}N}| = 1.51 \pm 0.10$ could be extracted from the available experimental data by assuming that the $s-$channel $Λ(1405)$ resonance plays a dominant role, whereas, the background contributions from the $s-$channel $Λ(1115)$, $t-$channel $K^*$ and $u-$channel nucleon pole processes are small and can be neglected. However, the $u-$channel nucleon pole diagram may also give an important contribution in the present calculations. After the background contributions are taken into account, the above value of $g_{Λ(1405)\bar{K}N}$ is reduced to $|g_{Λ(1405)\bar{K}N}| = 0.77 \pm 0.07$, which is not supported by the previous calculations and the recent CLAS measurements. The theoretical calculations on differential cross sections are also presented, which can be checked by future experiments.

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