n&pi invariant mass spectra constructed from (n onNT, &pi onTC) and (n onTC, &pi onNT) events

n&pi invariant mass spectra constructed from (n onNT, &pi onTC) and (n onTC, &pi onNT) events.

Suppression of combinatorial background by VcaVn

n&pi invariant mass spectra constructed from (n onNT, &pi onTC) and (n onTC, &pi onNT) events. The events with positive VcaVn are plotted by red, while green if not.

n&pi invariant mass spectra/&Sigma N event definition for specific event sets

The topology-by-topology n&pi invariant mass spectra are plotted below for all 8 cases. As easily seen, the &Sigma yield and S/N ratio are much different between the events, hence we do need to invoke special selections case-by-case.

Case-by-case n&pi invariant mass spectra. The events with positive VcaVn are plotted by red, while green if not. Note that no VcaVn selection is imposed for topology 3

Final form of topology-by-topology n&pi invariant mass spectra.

Case1 p 180degree (top panel) and Case1 p 90degree (bottom panel). On both, the black is constructed under 300MeV/c>p_&pi>135 MeV/c. The red is the subsets of the black fulfills the requirents for decay particles. The green is the one constructed from the complement.

Case1 n 180degree (top panel) and Case1 n 90degree (bottom panel). On both, the black is constructed under 300MeV/c>p_&pi>135 MeV/c. The red is the subsets of the black fulfills the requirents for decay particles. The green is the one constructed from the complement.

Case2 p 90degree (top panel) and Case2 p 180degree (bottom panel).

Case2 n 90degree (top panel) and Case2 n 180degree (bottom panel).

Case3 p 90degree (top panel) and Case3 n 90degree (bottom panel).