Particle composition and 1D-spectra

• Composistion and Kinematics Variables

  	Chgd+Neut (hid==911)	Chgd (hid==911)	Chgd+Neut (hid!=911)	Chgd (hid!=911)
  🆕 Composition of the particle list	\( \begin{aligned} 6 \leq N_{\rm trk} < 10 &: 6.8202 \times 10^{6}/2.78772 \times 10^{8} &= 2.45 \% \\ 10 \leq N_{\rm trk} < 12 &: 414728/2.01802 \times 10^{7} &= 2.06 \% \\ 12 \leq N_{\rm trk} < 14 &: 40578/2.10053 \times 10^{6} &= 1.93 \% \\ 14 \leq N_{\rm trk} &: 1985/103955 &= 1.91 \% \end{aligned}\)	\( \begin{aligned} 6 \leq N_{\rm trk} < 10 &: 72225/1.41143 \times 10^{8} &= 0.05 \% \\ 10 \leq N_{\rm trk} < 12 &: 5333/1.20971 \times 10^{7} &= 0.04\% \\ 12 \leq N_{\rm trk} < 14 &: 962/1.34604 \times 10^{6} &= 0.07\% \\ 14 \leq N_{\rm trk} &: 105/70069 &= 0.15 \% \end{aligned} \)	\( \begin{aligned} 6 \leq N_{\rm trk} < 10 &: 2.71952 \times 10^{8}/2.78772 \times 10^{8} &= 97.55 \% \\ 10 \leq N_{\rm trk} < 12 &: 1.97654 \times 10^{7}/2.01802 \times 10^{7} &= 97.94 \% \\ 12 \leq N_{\rm trk} < 14 &: 2.05995 \times 10^{6}/2.10053 \times 10^{6} &= 98.07 \% \\ 14 \leq N_{\rm trk} &: 101970/103955 &= 98.09 \% \end{aligned} \)	\( \begin{aligned} 6 \leq N_{\rm trk} < 10 &: 1.41071 \times 10^{8}/1.41143 \times 10^{8} &= 99.95 \% \\ 10 \leq N_{\rm trk} < 12 &: 1.20917 \times 10^{7}/1.20971 \times 10^{7} &= 99.96 \% \\ 12 \leq N_{\rm trk} < 14 &: 1.34508 \times 10^{6}/1.34604 \times 10^{6} &= 99.93 \% \\ 14 \leq N_{\rm trk} &: 69964/70069 &= 99.85 \% \end{aligned} \)
  thrust axis calculated w/ BBG
  thrust axis calculated w/o BBG

• Conclusion:
  The beam background particles do have impact on the calculation of thrust axis, and the effect can be seen in bbg particles' \( \theta_{\rm thr} \) distribution.

  thrust axis calculated w/ BBG (Chgd+Neut, hid==911)	thrust axis calculated w/o BBG (Chgd+Neut, hid==911)

  
  However, this is not a big effect, since beam background just makes up small fraction of particle lists, and comparing distributions of non-bbg particles in thrust frame, one will find almost no changes.

  thrust axis calculated w/ BBG (Chgd+Neut, hid!=911)	thrust axis calculated w/o BBG (Chgd+Neut, hid!=911)

  
  

Beam background particle contributions in the 2PC

(bbg x bbg)

• Beam axis 2PC

  	\(6 \leq N_{\rm trk} < 10\)	\(10 \leq N_{\rm trk} < 12\)	\(12 \leq N_{\rm trk} < 14\)	\(14 \leq N_{\rm trk} \)
  thrust axis calculated w/ BBG
  thrust axis calculated w/o BBG

• Thrust axis 2PC

  	\(6 \leq N_{\rm trk} < 10\)	\(10 \leq N_{\rm trk} < 12\)	\(12 \leq N_{\rm trk} < 14\)	\(14 \leq N_{\rm trk} \)
  thrust axis calculated w/ BBG
  thrust axis calculated w/o BBG

(bbg x !bbg)

• Beam axis 2PC

  	\(6 \leq N_{\rm trk} < 10\)	\(10 \leq N_{\rm trk} < 12\)	\(12 \leq N_{\rm trk} < 14\)	\(14 \leq N_{\rm trk} \)
  thrust axis calculated w/ BBG
  thrust axis calculated w/o BBG

• Thrust axis 2PC

  	\(6 \leq N_{\rm trk} < 10\)	\(10 \leq N_{\rm trk} < 12\)	\(12 \leq N_{\rm trk} < 14\)	\(14 \leq N_{\rm trk} \)
  thrust axis calculated w/ BBG
  thrust axis calculated w/o BBG

• Conclusion:
  
  • There is some enhanced correlation in the long-range, near-side area, for the sample of thrust axis calculated w/ BBG, but the shape is quite random (flat) in the beam 2PC.

    Thrust 2PC	Beam 2PC

    
    
  • The reason why (bbg x !bbg) thrust 2PC having special enhancement could be that in this exercise, we will select, especially, events with trigger particles passing high purity requirement (200MeV+), and this means their momenta is non-trivial (cannot be ignored), thus will have larger impact on thrust calculation. After taking away the bbg ptl in the calculation of thrust axis, the 2PC becomes a lot smoother.

    thrust axis calculated w/ BBG	thrust axis calculated w/o BBG

    
    

  🆕 bbg ptl effect in the consistency of gen and reco level

  • Here show and compare the 1D Y(Δɸ) distribution for:
    (1) gen level
    (2) reco level
    (3) reco level w/ bbg removed, but maintaining the thrust axis
    (4) reco level w/ bbg removed, and also re-calculate the thrust axis:
    

    

    	Ratio of long range Y(Δɸ)
    gen v.s. reco
    gen v.s. reco (w/ bbg removed, but maintaining the thrust axis)
    gen v.s. reco (w/ bbg removed, and also re-calculate the thrust axis)

  • Conclusion:
    Since the beam background particles only make up very little fraction (no bigger than 3%) in the particle lists within per event, we observe alomst no difference w/ or w/o beam background.