Charm-anticharm baryon production asymmetries in photon-nucleon interactions

TL;DR

This paper measures charm-anticharm baryon production asymmetries in photon-nucleon interactions, revealing a significant positive asymmetry for $ extLambda_c^+$ baryons and consistent asymmetries for excited states, providing insights into charm production mechanisms.

Contribution

First measurement of charm-anticharm baryon production asymmetries in photon-nucleon interactions, including differential asymmetries for $ extLambda_c$ baryons as functions of kinematic variables.

Findings

Integrated asymmetry for $ extLambda_c^+$ is 0.111 ± 0.018 ± 0.012.

Asymmetries of excited states are consistent with $ extLambda_c$ asymmetry.

Significant non-zero asymmetry indicates production mechanism asymmetries.

Abstract

We report measurements of the charm-anticharm production asymmetries for $\Lambda_c^+$, $\Sigma_c^{++}$, $\Sigma_c^0$, $\Sigma_c^{++*}$, $\Sigma_c^{0*}$, and $\Lambda_c^+(2625)$ 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 $\Lambda_c$ baryons as functions of $p_L$, $p_T^2$, and $x_F$. The integrated asymmetry for $\Lambda_c^+$ production, $(\sigma_{\Lambda_c^+} - \sigma_{\Lambda_c^-}) / (\sigma_{\Lambda_c^+} + \sigma_{\Lambda_c^-})$, is $0.111 \pm 0.018 \pm 0.012$, significantly different from zero. The asymmetries of the excited states are consistent with the $\Lambda_c$ asymmetry.