Mattione Kaon PID Studies Y2175

Reaction

• γ p → Y(2175), p
  • Y(2175) → f₀(980)⁰, φ
    • f₀(980)⁰ → π⁺, π^-
      • 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.
  • If a cut is shown, then all "Post-KinFit" plots after that cut include it.

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

Detector	% of Pions That Fail Kaon Cut	Pions That Fail Kaon Cut	Pions That Survive Kaon Cut
No CKOV		NA	NA
He DC	23.57%
Gas Threshold	10.24%
HBRICH	98.40%
LHCb RICH	98.01%

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.

Detector	% of Pions That Fail Kaon Cut	Pions That Fail Kaon Cut	Pions That Survive Kaon Cut
No CKOV		NA	NA
He DC	22.92%
Gas Threshold	7.55%
HBRICH	56.77%
LHCb RICH	60.42%

Yield %'s & Signal / Background Ratios

• ALL data are determined in the signal region (track combinations with invariant mass outside of the signal region are ignored), and from E_γ = 8.5 - 9.0 GeV

Yield %'s

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

Detector / PID Cut	Missing p, No Fit	Missing p, P4 Fit	Missing p, VertexP4 Fit	No Missing, No Fit	No Missing, P4 Fit	No Missing, VertexP4 Fit
No CKOV	9.66363%	9.91859%	7.50864%	5.08872%	3.3008%	2.64085%
He DC K: 1 Exclusive	7.6393%	7.75866%	5.92137%	4.00075%	2.58191%	2.06825%
Gas Threshold K: 1 Exclusive	9.34382%	9.60139%	7.32316%	4.92314%	3.2149%	2.57775%
HBRICH K: 1 Exclusive	9.17437%	9.41574%	7.18456%	4.83356%	3.15836%	2.53028%
LHCb RICH K: 1 Exclusive	9.25765%	9.51254%	7.2575%	4.87959%	3.19227%	2.55721%

Exclusive Kaon Cut Signal Yield Loss

•  % of pre-CKOV signal events LOST due to exclusive Kaon cut

Detector / PID Cut	Missing p, No Fit	Missing p, P4 Fit	Missing p, VertexP4 Fit	No Missing, No Fit	No Missing, P4 Fit	No Missing, VertexP4 Fit
He DC K: 1 Exclusive	20.9479%	21.7766%	21.1393%	21.38%	21.7791%	21.6826%
Gas Threshold K: 1 Exclusive	3.30938%	3.19803%	2.47022%	3.25377%	2.60219%	2.38949%
HBRICH K: 1 Exclusive	5.06284%	5.06975%	4.31607%	5.01412%	4.31516%	4.18701%
LHCb RICH K: 1 Exclusive	4.20113%	4.09389%	3.34465%	4.10968%	3.28807%	3.16726%

Signal / Background Ratios

• Signal / Background Ratios

Detector / PID Cut	Missing p, No Fit	Missing p, P4 Fit	Missing p, VertexP4 Fit	No Missing, No Fit	No Missing, P4 Fit	No Missing, VertexP4 Fit
No CKOV	0.00106212	0.00136379	0.0250697	0.0135034
He DC K: Inclusive	0.00117589	0.00153125	0.0365619	0.0171601
Gas Threshold K: Inclusive	0.00109474	0.00140526	0.0343859	0.0150712
HBRICH K: Inclusive	0.00126519	0.00166155	0.0585217	0.0309852
LHCb RICH K: Inclusive	0.00121623	0.00160001	0.0530719	0.0247906
He DC K: 1 Exclusive	0.00312333	0.00395292	0.0658157	0.0337837
Gas Threshold K: 1 Exclusive	0.00343035	0.00432616	0.0813565	0.0311833
HBRICH K: 1 Exclusive	0.00397305	0.00518064	0.104682	0.0524333
LHCb RICH K: 1 Exclusive	0.00385906	0.00495419	0.105741	0.0427721

Signal / Background Ratios : Improvements Over No CKOV

• Detector Signal / Background Ratio (StBR) DIVIDED BY No CKOV StBR

Detector / PID Cut	Missing p, No Fit	Missing p, P4 Fit	Missing p, VertexP4 Fit	No Missing, No Fit	No Missing, P4 Fit	No Missing, VertexP4 Fit
He DC K: Inclusive	1.10711	1.1228	1.45841	1.2708
Gas Threshold K: Inclusive	1.03071	1.03041	1.37161	1.11611
HBRICH K: Inclusive	1.19119	1.21834	2.33436	2.29462
LHCb RICH K: Inclusive	1.14509	1.17321	2.11697	1.83588
He DC K: 1 Exclusive	2.94065	2.89849	2.6253	2.50187
Gas Threshold K: 1 Exclusive	3.22971	3.17217	3.24521	2.30929
HBRICH K: 1 Exclusive	3.74067	3.79871	4.17563	3.88297
LHCb RICH K: 1 Exclusive	3.63334	3.63267	4.21788	3.16751