Local Charged Particle Multiplicity Fluctuations in PHENIX

1. Local Charged Particle Multiplicity Fluctuations in PHENIX Tarun Kanti Ghosh for the PHENIX Collaboration Vanderbilt University APS meeting / Albuquerque 04/20/02

2. Motivation • This is famous and unusual JACEE event • In circle area : one charged hadrons and many photons • Does it DCC? Do we expect to see such events at RHIC? O Photon + Charged Particle Anti Centauro APS meeting / Albuquerque 04/20/02

3. DCC Signal • Likely many uncorrelated domains can be formed, then this asymmetric distribution will become Gaussian • S0 such fluctuations should be looked in localized  or  space, localized momentum space • We look for localized charged fluctuations in -space to isolate the rare events that may correspond to higher or lower value of “f”. APS meeting / Albuquerque 04/20/02

4. Wavelet : Formalism • Wavelets jk() are the set of orthogonal functions where index j labels the scale and k labels the spatial bin • We use Discrete Wavelet Transformation technique to extract events with localized fluctuations in eta space over large events sample • Define Sample function f() = 1- Nch()/Nch() • Expansion for a given scale j fj() =  fjkjk() • Wavelet coefficients fjk = 2j f()jk() d • Power Pj = (1/2j) |fjk|2 APS meeting / Albuquerque 04/20/02

5. Wavelet : stairwell function Wavelet functions jk() = (2j  - k) 1 for 0  x  1/2 (x) = -1 for 1/2  x  1 0 otherwise j k 0 0 1 0 1 1 2 0 2 1 2 2 2 3  =0 =1 APS meeting / Albuquerque 04/20/02

6. Wavelet Transform: Daubechies • We are using D-4 wavelets in the DWT • Linear operation that operates on a data vector : a[n] • Length n of the data vector is an integer power of 2 • Transform to a numerically different vector of same length • A particular set of wavelets are specified by a particular set of numbers : wavelet filter coefficients • Daubechies ( D-4) : c0, c1, c2, c3 This is what a D-4 wavelet basis Looks like at j=2 APS meeting / Albuquerque 04/20/02

7. Simulation: FFC • Wavelet coefficients fjk = 2j f()jk() d plotted at different scale j • Simulated data with fluctuation size  = 30% where  = Ncand./Nmult • Distributions become wider by adding the fluctuations in simulated data wih HIJING APS meeting / Albuquerque 04/20/02

8. Acceptance pseudo-rapidity • We looked for PHENIX global tracks projected on three pad chamber detectors • Gap at Z=0 for PC2 & PC3 • PC3 further away from PC1 • PC2 only in one side  = .7 j=1  = .7/21 = .35 j=5  = .7 / 25 = .022 APS meeting / Albuquerque 04/20/02

9. Wavelet Coefficients @200 GeV tracks projected to PC1: PHENIX data is not significantly different from simulated data and mixed events. APS meeting / Albuquerque 04/20/02

10. Wavelet Coefficients @200 GeV tracks projected to PC2: PHENIX data is not significantly different from simulated data and mixed events. APS meeting / Albuquerque 04/20/02

11. Wavelet Coefficients @200 GeV tracks projected to PC3 : PHENIX data is not significantly different than the simulated data and mixed events APS meeting / Albuquerque 04/20/02

12. Power Spectrum@200 GeV • Correlation in power spectrum is similar for PHENIX data, mixed events, and in simulated data. Random sample shows a flat power spectrum. • This is work in progress. This sample has 60K PHENIX events and 120K mixed events. power spectrum is convolution of physics results and detector effects APS meeting / Albuquerque 04/20/02

13. Summary • DWT can be effective tool to look for Charged particle fluctuations in pseudo-rapidity space • Analysis was performed for a small fraction of 200 GeV Au+Au data and current status of this analysis is work in progress • Comparison is made with simulated and mixed events using similar cuts • Correlation in power spectrum is consistent with the detector acceptance for this sample of minimum bias PHENIX data • Rare events can be searched from the tail of ffc distribution APS meeting / Albuquerque 04/20/02