# Presentation: 914056

## Event-by-event charge/neutral fluctuation at RHIC-PHENIX

- Tomoaki Nakamura / Kensuke Homma
- Hiroshima University
- for the PHENIX collaboration

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## Why fluctuation ?

- Fluctuations carries information at early universe in cosmology despite of the only single Big-Bang event.
- Why don’t we use the genuine event-by-event information by getting all phase space information to study evolution of dynamical system in Heavy Ion collisions ?
- We can firmly search for interesting fluctuations with more than million times of mini Big-Bangs.

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## Physics motivation

**WMAP have seen the fluctuation of  CMB**** ****at the recombination.**

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## Au+Au √sNN = 200GeV at PHENIX

**Using magnetic field-off**
**Charged Track                 ****  **Drift chamber, Pad chamber1 with BBC vertex
**Photon Cluster****             **Electro-magnetic calorimeter
- Cluster shower shape
- Time of flight
- association cuts by tracks
**Precisely data quality assurance was necessary to reject detector effect!**

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## Event sample and a normal event

- _Event sample and a normal event_

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## Observable

**Balance**

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## How to extract region?

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## High energy cosmic ray experiment and PHENIX

**Can DCC scenario explain these events or something else?**

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## Maximum differential balance distributions

**δ****Bmax distribution (each centrality:10%)              with base line fluctuation**
- black : binomial sample, 100 times larger statistics than real data obtained by hit map
- red : data

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## N-participant dependence of the event fraction above 5% significance level

- _N-participant dependence of the event fraction above 5% significance level_

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## Summary and plan

- Fraction of events above 5% significance level to exclude binomial fluctuation with respect to minimum bias events increases as N-participants increases.
- Known fluctuations measured by the other experimental observables in our experiment will be parameterized and tested by our observable separately to investigate the source of fluctuations.
- Jets : two particle correlations and mean pT fluctuation
- Flow effect (would be negligible): V2 analysis
- Bose-Einstein correlation : subdivided multiplicity distributions with Negative Binomial Distribution

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## Back up slide

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## Baseline fluctuation

- Yellow band is one of the systematic error coming from ambiguity of limit value as 95% significance level.
- Baseline fluctuation have also a feature of enhancement of fraction at the low multiplicity events and at small resolution level. This algorism can not select large window at the low multiplicity. This is a feature of nature. So we subtracted the baseline fluctuation made by binomial based on hit map.

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## level-by-level

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## wavelet algorism (2 scale relation)

- Scaling function

- Wavelet function

- Level j-1 : 2j-1 bins

- Level j : 2j bins

- φ(2x)    = 1/√2 {φ(x) + ψ(x) }
- φ(2x-1) = 1/√2 {φ(x) - ψ(x) }

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## Multi resolution analysis

- Signal

- φ

- ψ

-  c jk

-  d jk

- j=4

- j=3

- j=2

- j=1

- j=0

-  j : resolution level
-      (domain size)
-  k : k-th bin in rapidity
- c jk  : coefficients of φ
_**d jk : coefficients of ψ**_
**d jk corresponds to**
**subtraction between two**
**neighboring bins except**
**scaling factor**

- k

- k

**+**

**+**

**+**

**+**

- 22

- 20

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003

## Window shift

- Shift the start bin at each
- resolution level.
- Find djk max among all of levels.
- This can determine the level
- (domain size) with the largest
- deviation size.

- should appear here !

- A symmetric structure
- appears in wrong level

- djk is lower

- Tomoaki Nakamura - Hiroshima Univ.

- 9/11/2003