THEROY ESTIMATE
Used data(from "STAR Collaboration Decadal Plan")

Our rapidity range： -1<y<1
Ratio between pi-mu and pbar-mu :
       
      Ratio  =  (9e-5*2)/(4e-6*2) = 22.5
 
ESTIMATE RUN10 CENTRAL
1>estimate  pbar-mu raw yield
Fig 1 p-mu net mass distribution

Fig 2 pbar-mu net mass distribution

Define UL*LS/ME2 = SIG
raw yield = SUM(ME[i]*(SIG[i]-1)) = 1.10571 //ME[i] and SIG[i] are bin content.
Integral Range: 0-0.02

2>estimate pi-mu raw yield

The clc method are the same with p-mu.
raw yield = SUM(ME[i]*(SIG[i]-1)) = 31.9285

Ratio between pi-mu and p-mu

        Ratio = 31.9285/1.10571 = 28.876

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I also calculated pi-mu and k-mu
Result :

QUESTIONS
1> Background
    I just used Mix event ,not mix event square  and all the  mix event is scaled to Unlike-sign(not the raw Mix event content)
2>pi-mu and k-mu
    It is shows a big different .I checked the net mass distribution , two sink around 0.02GeV/C2,that the reason .