Di-muon mass plot

This plot shows the ϒ signals in the 4<p_T<6 GeV/c range reconstructed in CMUP+CMU (top) and in CMUP+CMX (bottom) trigger paths. The displaced track component is hatched. A small region of invariant mass in the non-displaced sample is removed from the fit so that it will not be biased by final state radiation from the ϒ(1S) decay. This fit is used to determine the fraction of the ϒ(nS) signal that is present in the displaced muon component.

The following plot shows the ratio of the invariant mass distributions in the prompt and displaced muon samples. The superimposed function is a linear fit to the displaced muon sample and the sidebands of the prompt sample, indicated by the arrows. In this way, the scale factor is not influenced by the modeling of the ϒ(nS) signal structure and radiative tails in the invariant mass distribution.