Difference between revisions of "Mattione Kaon PID Studies Y2175"

Revision as of 00:25, 16 September 2012

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

• NOTES:
  • Plots are shown for "Missing p, VertexP4 KinFit" only.
  • Mass Plots: Pre-KinFit is Magenta, Post-KinFit is Teal
  • Kinematic Fit Confidence Level is zoomed in: spike at 0 confidence is well off the top of the plot
  • For the genr8 background, It wasn't possible to lineup every mass peak (without generating the recoil proton at a bogus mass), so the missing mass peak is a little off-center.

Plot	genr8 Y(2175) Signal	genr8 Y(2175) Background	bggen Background
Confidence Level
φ Mass
Missing Mass
Y(2175) Mass

Cherenkov Detector Comparison

genr8 Y(2175) 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.
  • Plots are shown for "Missing p, VertexP4 KinFit" only.

Design	% of Pions That Fail Kaon Cut	Pions That Fail Kaon Cut	Pions That Survive Kaon Cut
All		NA	NA
He DC	a% Survive, b% Fail
Gas Threshold	a% Survive, b% Fail
RICH	a% Survive, b% Fail
LHCb RICH	a% Survive, b% Fail

bggen 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.
  • Plots are shown for "Missing p, VertexP4 KinFit" only.

Design	% of Pions That Fail Kaon Cut	Pions That Fail Kaon Cut	Pions That Survive Kaon Cut
All		NA	NA
He DC	a% Survive, b% Fail
Gas Threshold	a% Survive, b% Fail
RICH	a% Survive, b% Fail
LHCb RICH	a% Survive, b% Fail

Yields %'s

• ALL yield %'s are determined in the signal region (track combinations with invariant mass outside of the signal region are ignored)

genr8 Y(2175) Signal Events

•  % of generated events remaining after all cuts (including a final cut requiring that all tracks have the correct THROWN PID)

•  % of BAD reconstructed combos remaining (BAD combo: a combo where at least one track has the wrong THROWN PID)

genr8 Y(2175) Background Events

•  % of reconstructed combos remaining

bggen Background Events

•  % of reconstructed combos remaining