# Presentation: 706368

## Meson Production in d – Au and Au – Au  Collisions at  √sNN = 200 GeV

- Fall DNP 2004, Chicago

**Notes:**

Show also NA50 low-mass spectrum?

## Outline

**Motivation**
**PHENIX experiment**
******mesons in d-Au collisions **
**Line shape analysis**
**Yield analysis**
** ****Centrality dependence**
** ****Comparison with Au – Au results**
**     ****(for Au – Au ************K****+****K****-**** reults, see the presentation JB9 by D. S. Mukhopadhyay)**
**Summary and outlook**

- Fall DNP 2004, Chicago

**Notes:**

Show also NA50 low-mass spectrum?

## Physics motivation

_****__** **__**mesons**_
**Chiral symmetry restoration and medium effects**
**     ****- mass shift, width broadening**
**    **
**     ******** ****Line shape analysis**
**Strangeness production**
**    ****- ******** meson yield and centrality dependence**
_**Au – Au & d – Au collisions**_
**Distinguish between hot and cold partonic matter**
**Evolution of medium properties with density and temperature**
**Probing nuclear effects**
**        **

- Fall DNP 2004, Chicago

**Notes:**

Show also NA50 low-mass spectrum?

## PHENIX Setup

**Tracking :**** DC – PC1       – PC3**
**    ****Momentum **

_**PHENIX Setup**_

**Collision vertex and centrality:**
-  **Beam-beam Counter**

_****__****__****__****__****_
**Kaon identification: **** **
**TOF: |********| < 0.35, ******** = 45****o**** **
**PbSc (East):  |********| < 0.35, ******** = 45****o**
**PbSc (West): |********| < 0.35, |********| = 90****o**

**K****-**

**K****+**

**K****+****K****-**

**K****+****K****-**

**K****+     ****K****-**

- Fall DNP 2004, Chicago

**Notes:**

Show also NA50 low-mass spectrum?

## Line  shape analysis

**Minimum bias events**
**N****evt**** = 54 M**
**Fitting function:**
**Breit Wigner convolved with **
**Gaussian ****Mass resolution function **
**of  ******** ~ 1.4 MeV/c****2**
**Minimum bias centroid and width is**
**consistent with PDG values:**
**<m>****PDG**** = 1.019456 GeV/c****2**
******   ****=  4.26 MeV/c****2**
****** ****Study the centrality dependence**
**     ****of line shape.**

**d – Au collisions at ****√s****NN**** = 200 GeV**
********** ****K****+****K****-**

**S = 786 ±  34, S/B = 1/0.47**

**<m> = 1.01911 ****± 0.00016 ****±  0.00085 GeV/c****2**

** ****(stat)            (syst)**

****** ****= 4.567±0.441 (stat)± 0.313 (syst) MeV/c****2**

**Work-in-progress**

- Fall DNP 2004, Chicago

## Centrality dependence of Line shape

_** **__****__**  **__**meson’s line shape in cold nuclear matter:**_**  **
** ****Centroids are consistent with PDG at all centralities**
**  ****Widths are consistent with PDG within less than 2******
****

**Systematic error band**

**Systematic error**

**PHENIX Preliminary**

**PHENIX Preliminary**

- Fall DNP 2004, Chicago

## mT spectrum (Minimum bias)

**Yield of ******** in each m****T**** bin is corrected with acceptance and reconstruction efficiencies by PHENIX MC simulation.**
**The corrected spectra is fitted with m****T**** exponential function with dN/dy and T as two fitting function.**
**Preliminary dN/dy and T of ******** in  K****+****K****-**** and e****+****e****-**** decay channels are consistent with each other.**
**      ****(See the presentation by D. Kotchetkov, JB003 for the status of ************e****+****e****-**** analysis)**

**Work-in-progress**

**Systematic error**

- Fall DNP 2004, Chicago

## mT spectrum (centrality selected)

_**m**__**T**__** spectrum (centrality selected)**_

- Fall DNP 2004, Chicago

**Systematic error**

**Systematic error**

**Systematic error**

**Systematic error**

**PHENIX Preliminary**

**PHENIX Preliminary**

**PHENIX Preliminary**

**PHENIX Preliminary**

**dN/dy = 0.016 ± 0.003 (stat) ± 0.003 (syst)**

**T = 313 ± 32(Stat) ± 22 (Syst) MeV**

- Fall DNP 2004, Chicago

## Centrality dependence: Yield

_**Centrality dependence: Yield**_

**    ****dN/dy increases with centrality and from d-Au to Au-Au system.**
**    ****dN/dy per participant pair is flat for d-Au system within errors, but**
**     ****increases from d-Au to Au – Au system.**

**Au-Au @ ****√s****NN****=200 GeV**
**(PHENIX Final)**

- Fall DNP 2004, Chicago

## Centrality dependence: Inverse slope

_**Centrality dependence: Inverse slope**_

**    ****The inverse slope is almost constant within different centrality classes **
**of d-Au and is consistent with Au-Au system.**

**Au – Au @ ****√s****NN**** = 200 GeV**
**(PHENIX Final)**

- Fall DNP 2004, Chicago

## Summary and outlook

******mesons are measured in d-Au and Au-Au collisions.**
**Preliminary results on  ******** meson line shape study  in d-Au collisions shows consistency with PDG values.**
**m****T**** spectra, dN/dy and T is measured at five centrality classes. **
**    ****Preliminary results show that both dN/dy and T are independent of centrality within errors.**
**Increase in dN/dy from d-Au (Preliminary) to Au-Au (Final) while the temperature remains almost constant within errors. **

- Fall DNP 2004, Chicago