# Presentation: 085805

## Bulk Particle Production A Global View

**Bulk Particle Production ****A Global View**

- Gunther Roland

## Bulk Properties

**Bulk Properties**

**Single Au+Au Collision**
**O(10****4****) 4-Vectors**

**Provide background (5 - 15% accuracy) against**
**which we can search for structure**

## Global Observables

## Control Parameters

**Also:  Different systems (different nuclei, pp, pA, e****+****e****-****)**

**System-Size**

**Energy**

## Bulk Properties

**Bulk Properties**

## I. Particle Density near Mid-Rapidity

**I.**** Particle Density near Mid-Rapidity**

**How does Density at 90****o ****change **
**with Energy and Centrality?**

## Particle Density near Mid-Rapidity

**Beware of the Jacobian!**
**dN/d******** = <********> dN/dy**

## Particle Density near Mid-Rapidity

**Particle Density near Mid-Rapidity**

**Logarithmic Rise with Collision Energy**

## Particle Density near Mid-Rapidity

**Particle Density near Mid-Rapidity**

**Models prior to RHIC**

## Centrality Dependence at | < 1

## II. 4- Multiplicity <Nch>

**How does Integral over 4-********, <N****ch****>, **
**change with Energy and Centrality?**

## Nch vs Npart in d+Au 

******N****ch******** vs N****part ****in d+Au **

**PHOBOS preliminary**

**PHOBOS preliminary**

**see talk by Rachid Nouicer**

**d+Au Multiplicity proportional **
**to p+p Multiplicity * N****part**

**<N****ch****>****pp*****N****part**

## Nch vs Npart in Au+Au 

******N****ch******** vs N****part ****in Au+Au **

**200 GeV**

**130 GeV**

**19.6 GeV**

**Pseudorapidity**

**dN/d********/<1/2 N****part****>**

**200 GeV**

**19.6 GeV**

**central**

**peripheral**

**central**

**peripheral**

**<N****ch****>****e+e-*****N****part**

**Au+Au Multiplicity proportional to N****part**

## III. Shape of dN/d Distributions

**How does Shape of dN/d******** (dN/dy) **
**change with Energy? **

**Reaching the Central Plateau?**

## Boost-invariance?

******+**** dN/dy spectra**

**Single Gaussian **_**fits**_** from 2 to 200 GeV**

## Landau Hydrodynamics

**Carruthers, Duong-Van on pp data in **_**1973**_**:**

## <Nch> vs sqrt(s) revisited

**<N****ch****> vs sqrt(s) revisited**

**Carruthers, Duong-Van on pp and e****+****e****-**** data in 1983:**

## IV. Spectrum of Produced Hadrons

**Yield**

**Mass**

**Quantum Numbers**

**Temperature**

**Chemical Potential**

**Hagedorn, Becattini, Braun-Munzinger, Cleymans,**
** ****Letessier, Mekijan,Rafelski, Redlich,Stachel, Tounsi**

## Spectrum of Produced Hadrons

## “Thermal Fit” Parameters vs sqrt(s)

## V. Transverse Dynamics

## Structure in Inverse Slope vs sqrt(s)

**Structure in Inverse Slope vs sqrt(s)**

##  Summary

**Data can indeed by reduced efficiently**
- We’re doing Thermodynamics!
**Total Multiplicity**
- Proportional to Npart
- Rises like s1/4 from mid-SPS Energy Range
** ******** ****dN/dy Distributions**
- Single Gaussian with width  ~ 0.5 ln(s/4mp)
** ****Statistical Fits describe Hadron Abundances**
- Systematic Evolution, Limiting Temperature
**Correspondence with other ‘Hadronic’ Systems**
- p+p, p+A, e+e-
**Max Entropy Evolution from Dense Initial State**
**How is the Initial State Prepared?**
**Baryon Number Transport?**

## Slide 24

## Coincidence?

**Coincidence?**

**N****min**** - N****max**

**1.8**

**2.5**

**3.7**

**5.0**

**dN/d********|****|********<1**** /<0.5 N****part****>(200 GeV)**

**Ratio R****RHIC/SPS**

**This is a cartoon! (so far)**

**Model H**

**pp**

**e****+****e****-**

**A+A**

**Predictions**

## Particle Ratios in d+Au: p/p vs Centrality

**Constant p/p ratio vs centrality **
**Disagreement with expectations/models**

- nucl-ex/0309013 - submitted to PRC

- Au+Au
**Phys. Rev. C 67, 021901R (2003)**** **

## Npart scaling?

## Rapidity Distributions at 200 GeV

**Rapidity Distributions at 200 GeV**

- yT

- 

**Surprising agreement in shape between AA/e****+****e****- ****/pp**

- Correspondence between perturbative and non-perturbative approaches?

**e****+****e****-**** measures dN/dy****T****(rapidity relative to****“thrust” axis)**

**AA/pp ~ 1.4-1.5**

**200 GeV**
**Central Au+Au**

**q**

**q**

- PHOBOS QM’02, Steinberg

## Transverse Energy near =0

- dET/dexhibits smooth rise vs sqrt(s)
- Surprisingly, <ET> per particle at =0 constant
- even though p+p spectra get much harder with sqrt(s)

- PHENIX QM ‘02 nucl-ex/0209025

- PHENIX QM ‘02 nucl-ex/0209025

## Transverse Energy near =0

******<E****T****> < 10% **

******<p****T****> ~ 20% **

- PHENIX QM ‘02 nucl-ex/0209025

- STAR QM ‘02 nucl-ex/02111021

## Net Proton dN/dy

## Transverse Energy vs Npart

**STAR prel.**

**130 GeV**
**200 GeV**

**dE****T****/d********and <pT> independent of N****part ****above N****part**** ~50**

- PHENIX QM ‘02 nucl-ex/0209025

- STAR QM ‘02 nucl-ex/0211021, poster M. Calderon

## Boost-invariance?