Charm-anticharm baryon production asymmetries in photon-nucleon interactions

Abstract

We report measurements of the charm-anticharm production asymmetries for $Λ_c^+$, $Σ_c^{++}$, $Σ_c^0$, $Σ_c^{++*}$, $Σ_c^{0*}$, and $Λ_c^+(2625)$ baryons from the Fermilab photoproduction experiment FOCUS (E831). These asymmetries are integrated over the region where the spectrometer has good acceptance. In addition, we have obtained results for the photoproduction asymmetries of the $Λ_c$ baryons as functions of $p_L$, $p_T^2$, and $x_F$. The integrated asymmetry for $Λ_c^+$ production, $(σ_{Λ_c^+} - σ_{Λ_c^-}) / (σ_{Λ_c^+} + σ_{Λ_c^-})$, is $0.111 \pm 0.018 \pm 0.012$, significantly different from zero. The asymmetries of the excited states are consistent with the $Λ_c$ asymmetry.