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Heavy Flavor Group Simulation Analysis and Rejection Efficiency for Au+Au and d+Au Events

This document outlines the ongoing simulations for the Heavy-Flavor Group analysis, specifically focusing on Au+Au low multiplicity events and the upcoming need for d+Au simulations. The analysis explores rejection and efficiency metrics while simulating J/Psi signals in peripheral collision scenarios. It discusses algorithms for determining acceptance and trigger efficiency, particularly emphasizing the balance between energy thresholds and signal integrity. Future work includes further simulations to fine-tune the detection of J/Psi events against complex backgrounds.

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Heavy Flavor Group Simulation Analysis and Rejection Efficiency for Au+Au and d+Au Events

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  1. J/ Simulations for RUN III Manuel Calderon for the Heavy-Flavor Group Analysis Meeting at BNL October 23, 2002

  2. Simulations so far … • Rejection/Efficiency: Working on AuAu low multiplicity simulations only up to now. Need dAu simulations, can probably get higher rejection with lower multiplicity events. Use Seff = S/(2B/S + 1) • Background: • Minbias Au+Au (only last weekend did d+Au begin running…) • Select most peripheral 50% x-section: dN/dh = 11 (5.6 at 40%) to approx. d+Au multiplicity • Signal: • J/Psi simulated flat in pt and h to see efficiency vs pt • Will use more realistic pt distribution to see where most signal sits. • Throw one J/Psi in an empty event • Need to also mix them into a background event. • Using 3 cuts: Tower Energy (L0), Mass, Cos(q) (L2)

  3. Algorithm 1) Approximate the electron daughters with towers (or clusters) Energy, Position 2) Obtain vertex from BBC timing 3) Need at least 2 towers to make a pair (could require this at L0?) 4) Take all selected towers and make all possible pairs Minv  2E1E2(1-cos(q12)) 5) Do cuts in M and cos(q)… Still exploring possibilities Towers, clusters, cluster size?

  4. Algorithm : Need to explore various ideas • What are the best energy thresholds to use? • 1, 1.5, 2 GeV? Want acceptable resolution and not to kill the signal. • First tested with Tower Energy only: resolution not good! • Now testing various cluster approaches: 2 towers, or patches of various sizes (3x3, 5x5, 7x7, 9x9) 2-Tower Cluster Single Tower

  5. Acceptance and Trigger Efficiency J/Y • 1) Done at mid-rapidity with full EMC • 2) Trigger efficiency using Tower Energy (no clustering), and both towers with same threshold (1 GeV)

  6. Half EMC acceptance (pT - h) Raw Accepted electrons with E>1 GeV, 0.1 < h < 0.9

  7. Acceptance and Trigger Efficiency (Half Emc, Cluster) • Half Emc, 0.2 < h < 1

  8. J/Y Mass at Level 2 J/Y flat in pt-h Background Thrown mass L2 Mass, real E, real cos(q) L2 Mass, cluster E, real cos(q) L2 Mass, real E, cluster cos(q) L2 Mass, cluser E and cos(q) To do: simulate with some pT slope

  9. J/Y Mass at Level 2 (from today!) J/Y with slope 600 MeV Background (w/ dAu) Thrown mass L2 Mass, real E, real cos(q) L2 Mass, cluster E, real cos(q) L2 Mass, real E, cluster cos(q) L2 Mass, cluser E and cos(q) <M> = 2.93, 2.68 GeV sM = 300, 668 MeV Rejection Factor at L2 for loose cuts: 35 Goal: ~48 KHz/1KHz not too far

  10. Decay Topology: large opening angle for most J/Y Accepted J/Y (flat in pt-h) Background

  11. Isolation cuts… Compare tower (or “cluster”) energy to surrounding energy in patch For 3x3 patch Electrons

  12. To Do: • Still many simulations and tests to do to arrive at a good L2 Algorithm: • + Low multiplicity in d+Au will reduce the backgrounds • - Signal is faint ~ “one in a million” • - Half EMC drastically reduces acceptance • Need to try out • various patches, 3x3, 5x5 • Energy Thresholds • Mass Thresholds • Opening Angles • Isolation cuts

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