Mattione Update 06252012

Reaction

• γ p → Y(2175), p
  • Y(2175) → π⁺, π^-, φ
    • φ → K⁺, K^-
• Final State: p, π⁺, π^-, K⁺, K^-
• Events Generated using genr8 with: 9 GeV Photons, 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!)
• 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):
  • Require the detection of at least 2+ and 2- tracks (proton is treated as missing)
  • Require the combined FOM for PID (π⁺, π^-, K⁺, K^-) be > 1%
  • Place very loose cuts on the φ invariant mass (0.8 - 1.3) and p missing mass (0.5 - 1.4): reduces # of bogus track combinations to save time / cleanup histograms
  • Kinematic Fit: 4-momentum conservation: p missing mass, φ invariant mass
  • Require that the confidence level from the kinematic fit be > 1%

Thrown Track Parameters

• p vs θ

PID

• PID FOM

Initial Mass Peaks

• Initial Mass Peaks

φ Invariant Mass

Proton Missing Mass

Y(2175) Invariant Mass

Kinematic Fitting Plots

• Confidence Level

• Confidence Level vs. Mass

• Pulls (Confidence Level Cut at 10% for histogramming)
  • μ's = ~0.0, σ's = ~1.08

Track	px Pull	py Pull	pz Pull
γ
K+
K-
π+
π-

Final Mass Peaks

• Final Mass Peaks
  • The Y(2175) Invariant Mass is calculated using the kinematic fit values of the track 3-momenta.
  • The Y(2175) Invariant Mass is fit to Breit-Wigner over a quadratic background (I couldn't get the Voigtian fits to converge), and has Γ = ~80 MeV/c² (as opposed to the generated Γ = 0.061 MeV/²)

φ Invariant Mass

Proton Missing Mass

Y(2175) Invariant Mass