Difference between revisions of "Mattione Kaon PID Studies phi3(1850)"

Revision as of 18:33, 13 September 2012

Reaction

• γ p → φ₃(1850), p
  • φ₃(1850) → K⁺, K^-
• Final State: p, K⁺, K^-
• Events generated with: Γ_φ3(1850) = 87 MeV/c², t-slope = 5.0, 50.0 < Vertex-Z (cm) < 80.0

Analysis Overview

• For each q = +/- particle in the reaction, all detected q = +/- tracks are tested as to whether or not they are that particle
  • e.g. If a q = + track has PID FOM > 1% for both the π⁺ & K⁺: allow both combinations (DO NOT take the best FOM as true!)
• Maximum of 8 tracks per event (to cut down on memory spikes).
• The analysis (cuts/histing/kinfits) is then performed on each possible track combination (events are only cut if every one of their track combinations is cut):
  • Required 45.0 < Track-Vertex-Z (cm) < 85.0
  • Require the combined FOM for PID (χ² and NDF of all tracks summed together) be > 1%
  • Placed VERY wide cuts on the non-signal invariant mass peaks: reduces # of bogus track combinations to save time / cleanup histograms
  • Where kinematic fit: Require that the confidence level from the kinematic fit be > 1%

Mass Peaks & Kinematic Fitting

genr8 φ₃(1850) Signal

• Kinematic Fit Confidence Level (Zoomed in; spike at 0 confidence is well off the top of the plot)

Recoil p	P4 KinFit	VertexP4 KinFit
Missing	350px
Not Missing	350px

• Missing Mass & Missing Mass Squared (Before/after KinFit where present)

Recoil p	No KinFit	P4 KinFit	VertexP4 KinFit
Missing	350px	350px
Not Missing	350px	350px	350px

• φ₃(1850) Invariant Mass (Before/after KinFit where present)

Recoil p	No KinFit	P4 KinFit	VertexP4 KinFit
Missing	350px	350px
Not Missing	350px	350px

genr8 φ₃(1850) Background

• Generate pions instead of kaons, shift generated mass peaks so that when the kaon mass is assigned to the kaon candidates (pions), the mass peaks shift to the original signal masses.

• Kinematic Fit Confidence Level (Zoomed in; spike at 0 confidence is well off the top of the plot)

• Missing Mass & Missing Mass Squared (Before/after KinFit where present)

• φ₃(1850) Invariant Mass (Before/after KinFit where present)

bggen Background

• Kinematic Fit Confidence Level (Zoomed in; spike at 0 confidence is well off the top of the plot)

Recoil p	P4 KinFit	VertexP4 KinFit
Missing	350px
Not Missing	350px

• Missing Mass & Missing Mass Squared (Before/after KinFit where present)

Recoil p	No KinFit	P4 KinFit	VertexP4 KinFit
Missing	350px	350px
Not Missing	350px	350px	350px

• φ₃(1850) Invariant Mass (Before/after KinFit where present)

Recoil p	No KinFit	P4 KinFit	VertexP4 KinFit
Missing	350px	350px
Not Missing	350px	350px

Cherenkov Detector Comparison: genr8 φ₃(1850) Background

• P vs. θ of π⁺'s as K⁺ candidates ("All" means all post-analysis cuts, pre-Cherenkov cuts)
  • π^-'s as K^- not shown: identical due to symmetry.

π+ as K+	No Missing, P4 KinFit	No Missing, VertexP4 KinFit	p Missing, P4 KinFit	p Missing, VertexP4 KinFit
All	350px		350px || 350px
He DC	350px	350px	350px || 350px
Gas Thresh.	350px	350px	350px || 350px
RICH (Yi)	350px	350px	350px || 350px
LHCb RICH	350px	350px	350px || 350px

Cherenkov Detector Comparison: bggen Background