Mattione Kaon PID Studies Y2175

Reaction

• γ p → Y(2175), p
  • Y(2175) → π⁺, π^-, φ
    • φ → K⁺, K^-
• Final State: p, π⁺, π^-, K⁺, K^-
• Events generated with: Γ_Y(2175) = 61 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
  • EXTREMELY loose mass cuts around each mass peak (typically at the histogram edges): saves time by reducing # of kinematic fits to perform
  • Require the combined FOM for PID (χ² and NDF of all tracks summed together) be > 1%
  • Where kinematic fit: Require that the confidence level from the kinematic fit be > 1%
  • Mass cuts as illustrated.

Mass Peaks & Kinematic Fitting

genr8 Y(2175) Signal

• Kinematic Fit Confidence Level (Zoomed in; spike at 0 confidence is well off the top of the plot)
  • NOTE: φ mass is not constrained by kinematic fit.

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

• φ Invariant Mass (Before/after KinFit where present)
  • NOTE: φ mass is not constrained by kinematic fit.

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

• Y(2175) Invariant Mass (Before/after KinFit where present)

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

genr8 Y(2175) 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.
  • Note that it is impossible to get every peak to line up without generated a recoil proton with a bogus mass. Therefore, the missing mass peak is slightly off.

• Kinematic Fit Confidence Level (Zoomed in; spike at 0 confidence is well off the top of the plot)
  • NOTE: φ mass is not constrained by kinematic fit.

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

• φ Invariant Mass (Before/after KinFit where present)
  • NOTE: φ mass is not constrained by kinematic fit.

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

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

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

• Y(2175) Invariant Mass (Before/after KinFit where present)

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

bggen Background

• Kinematic Fit Confidence Level (Zoomed in; spike at 0 confidence is well off the top of the plot)
  • NOTE: φ mass is not constrained by kinematic fit.

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

• φ Invariant Mass (Before/after KinFit where present)
  • NOTE: φ mass is not constrained by kinematic fit.

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

• Y(2175) Invariant Mass (Before/after KinFit where present)

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