# Presentation: 354149

## The Landscape ofParticle Production:Results from                 . 

**The Landscape of****Particle Production:****Results from                 ****.**** **

**Peter Steinberg**
**Brookhaven National Laboratory**

- SPS

- FNAL

- RHIC

- SppS

- AGS

## PHOBOS Collaboration 2004

- Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Abigail Bickley,
- Richard Bindel, Wit Busza (Spokesperson), Alan Carroll, Zhengwei Chai, Patrick Decowski,
- Edmundo Garcia, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen, Stephen Gushue,
- Clive Halliwell, Joshua Hamblen, Adam Harrington, Conor Henderson, David Hofman, Richard Hollis,
- Roman Hołyński, Burt Holzman, Aneta Iordanova, Erik Johnson, Jay Kane, Nazim Khan, Piotr Kulinich, Chia Ming Kuo, Willis Lin, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Inkyu Park, Heinz Pernegger, Corey Reed, Michael Ricci,
- Christof Roland, **Gunther Roland**, Joe Sagerer, Iouri Sedykh, Wojtek Skulski, Chadd Smith,
- Peter Steinberg, George Stephans, Andrei Sukhanov, Marguerite Belt Tonjes, Adam Trzupek,
- Carla Vale, Siarhei Vaurynovich, Robin Verdier, Gábor Veres, Edward Wenger, Frank Wolfs,
- Barbara Wosiek, Krzysztof Woźniak, Alan Wuosmaa, Bolek Wysłouch, Jinlong Zhang
- 	ARGONNE NATIONAL LABORATORY	BROOKHAVEN NATIONAL LABORATORY
- 	INSTITUTE OF NUCLEAR PHYSICS, KRAKOW	MASSACHUSETTS INSTITUTE OF TECHNOLOGY
- 	NATIONAL CENTRAL UNIVERSITY, TAIWAN	UNIVERSITY OF ILLINOIS AT CHICAGO
- 	UNIVERSITY OF MARYLAND	UNIVERSITY OF ROCHESTER

## PHOBOS Highlights

- d+Au & p+p physics
- Multiplicity
- Inclusive Spectra
- PID
- Multiparticle Physics in Au+Au

## PHOBOS 2003

- Several crucial upgrades for d+Au

## Charged-Particle Multiplicities in p+p & d+Au

## Minimum-bias d+Au

**Minimum-bias d+Au**

- Predictions as of Oct. 2003

- See R. Nouicer’s talk

- nucl-ex/0311009

- PHOBOS

## Centrality Dependence of d+Au

- Data vs. AMPT

| Centrality   (%) | Npart | Npart(Au) | Npart(d) |
| --- | --- | --- | --- |
| 0-20 | 15.5  | 13.5 | 2.0 |
| 20-40 | 10.8      | 8.9 | 1.9 |
| 40-60 | 7.2 | 5.4 | 1.7 |
| 60-80 | 4.2 | 2.9 | 1.4 |
| 80-100 | 2.7 | 1.6 | 1.1 |

- PHOBOS Preliminary

- p+p poster by J. Sagerer

## Participant Scaling?

**Participant Scaling?**

- Multiplicity extrapolatedto 4****
- Relative to p+p multiplicity at same energy, scales with Npart/2
- No modification with
-  Beam energy
-  Nuclear thickness

## Is Npart Fundamental?

- Expectations:“stopping” in d direction“cascading” in Au direction
- Why do they add up toNpart scaling so robustly?
- Same effect in Au+Au
- “Long-range” correlation?

- nucl-ex/0311009

## (p)d+Au in Different Frames

- As with Au+Au, “limiting fragmentation region” grows with energy.
- Shape appears to be constrained by lower-energy p+A data.Surprising over 1.5 orders of magnitude in collision energy.

## Can we build Au+Au with p+p/d+Au?

**Can we build Au+Au with p+p/d+Au?**

- Fundamental differencebetween p+p / d+Au & Au+Au?

- Au+Au nucl-ex/0301017d+Au & p+p preliminary

- PHOBOS 200 GeV

## Multiparticle Physics:Fluctuations, HBT, Flow

## Forward Multiparticle Physics in Au+Au

- Fluctuations & Correlations
- HBT Correlations
- Azimuthal asymmetries

- Long-Rangevs.Short-Rangeeffects

- 4 multiplicity measurements show long-range correlation

## Forward-Backward Correlations

**Forward-Backward Correlations**

## Longitudinal Dynamics with HBT

**Longitudinal Dynamics with HBT**

**Boost Invariant**

**Static Source**

- PHOBOS Preliminary Au+Au 200 GeV(0.1 < kT < 1.4 GeV/c)

- NA49 (1998)(0.1 < kT <0.2 GeV/c)

- Particles at a givenrapidity are correlatedwith a sourceat the same rapidity
- Similar to FB result:correlations arelocal in rapidity.

- See talk by B. Holzman, poster by C.M.Kuo

- Open symbols reflected

## Directed and Elliptic Flow

- UrQMD

- DirectedFlow

- DirectedFlow

- y

- y

- v1

- v1p

- v1

- v1p

- v2

## Elliptic Flow vs. Centrality 

- Overall shape simple, but still unexplained

- See talk by M. Belt Tonjes

- Open symbols reflected

***200 GeV***

## Directed Flow vs. Energy

- Dramatic change of directed flow near =0

## “Limiting Fragmentation” of v1

**“****Limiting Fragmentation” of v****1**

- Similar directed flow relative to beam rapidity

- PHOBOS Au+Au Preliminary

## Connection with Net Baryons?

- Peak of baryon density at AGS/SPS at ’~-1.5
- (Busza & Goldhaber ‘84)

- BRAHMS, nucl-ex/0312023

## Directed & Elliptic Flow

**Directed & Elliptic Flow**

**QM2002 200 GeV v****2**** 3-50% **

**200 GeV v****1**** 6-55% **

- PHOBOS Preliminary

## Identified Particles in d+Au

## Ratios with dE/dx PID

- A “classic” PHOBOS measurement:
- Two charge signs,two bending directions...

- ...but now we have

- p+p

- d+Au

- Au+Au

## Identified Particle Ratios

**Identified Particle Ratios**

- p+p  d+Au : No modification (cf. multiplicity)
- Au+Au: Additional net-baryons near =0

- d+Au: nucl-ex/0309013
- Au+Au: PRC-R67 (2003)

- Poster by A. Bickley

- 200GeV

## PHOBOS TOF PID

**PHOBOS **_**TOF**_** PID**

**See talk by G.Veres**

- Spectrometertrigger enrichedd+Au data set

## Particle Ratios at High-pT

- Main difference between p and p is overall yield.
- Spectral shape only slightly modified vs. pT

- d+Au 200 GeV

## TOF PID Spectra d+Au

**TOF PID Spectra d+Au**

**Pending weak-decay correction**

## mT Scaling in d+Au and Au+Au

**m****T ****Scaling in d+Au and Au+Au**

- PossiblemT scalingin d+Au(pendingweak corr.)

## d+Au Inclusive Spectra vs.  

## Inclusive Charged Hadrons in d+Au

**Inclusive Charged Hadrons in d+Au**

- Au+Au and d+Auscale differentlyrelative to Ncoll

- PRL91, 072302 (2003)

## Spectra in d+Au for >0

**Spectra in d+Au for ********>0**

- Systematic decrease in Rd+Au with increasing ****
- Saturation of ratio also occurs at a lower pT

**See poster by J. Kane**

## -Dependence of Rd+Au

- Monotonic evolution from mid-rapidity to forward rapidities.BRAHMS data is a continuation of trends starting at =0

## The Landscape of Particle Production

**The Landscape of Particle Production**

- SPS

- FNAL

- RHIC

- SppS

- AGS

-  Multiplicity measurements
-  Npart scaling & limiting fragmentation
-  Long range correlations in ?

-  Forward Multiparticle Physics in Au+Au
-  FB & HBT show effects local in  for ||<3
-  First measurement of directed flow vs.  & s

-  Identified Particle Spectra in d+Au
-  PID Spectra in d+Au, Au+Au for Run-4
-  Proton and antiproton spectra similar

-  Inclusive d+Au Charged Spectra vs. 
-  Strong  dependence interpolates    between =0 and forward 

## Backup Slides

## Relative Yields vs. pT

- PHOBOS d+Au 200 GeV

## mT Scaling and Strangeness

- Factor of 2 brings K’s into line (s ~ 0.5 in pp)

## PHOBOS Coverage

- N Rings

- P Rings

- Octagon

- Spectrometer

- Nowhere to hide!

## Principal Axes

- Heavy-ion collisions dominatedby Npart fluctuations
- Decouple total fromrelative fluctuations
- Independently partitionedbetween P & N

**N**

**P**

**P+N**

**P – N  **

- (flipping a coin, random walk...)

## Forward-Backward Correlations

**Forward-Backward Correlations**

## Simple Exercise

- Let’s play a game:
- Shift PYTHIA dN/dyby y = 1
- Scale up by Npart/2
- Recalculate dN/d
- Similar shapes
- (violates energy conservation ****)

## Participant Scaling

**PHOBOS QM ’02**

- Wounded Nucleon“Scaling”

- 

- 

- _Transition to d+Au_