Summary of Recent PHENIX Results

04/22/2023 2013 RHIC & AGS Annual Users' Meeting 1

Summary of Recent PHENIX Results

J. Lajoie, Iowa State University


Outline

• d+Au and Cold Nuclear Matter• Geometry studies with Cu+Au• Spin and nucleon structure

We have entered a detailed exploration phase at RHIC where we are now able to begin separating fundamental QCD from non-ideal effects (CNM, geometry,…).


The Devil’s in the Details


The Baryon Anomaly (Au+Au)

proton/pion antiproton/pion

PRL 91, 172301 (2003), PRC 69, 034909 (2004)

Excess (anti) baryons compared to pions at moderate pT (2-5 GeV/c).

Does not look like vacuum jet fragmentation.


The Baryon Anomaly in d+Au?The start of the “Baryon Anomaly” is present in CNM – not a QGP effect? Or is it? Challenges explanations that require a high parton density.

Central d+Au ratios look a lot like peripheral Au+Au ratios.

Clear enhancement of baryons as a function of centrality.

PHENIX arXiv:1304.3410v1


arXiv:1303.1794

Near- and away-side features seen in both central and peripheral; Δη gap limited to Δη>0.5

Two-Particle CorrelationsVery similar to LHC! Central-peripheral difference is symmetric: two ridges? or flow?


Fourier moments Cn of (Cent-Periph) distributions

versus associated pT

Inferred quadrupolar anisotropy v2 of h+- vs pT

PHENIX arXiv:1303.1794

Just Geometry + Flow?

arXiv:1304.3403


xd~xAu

PHOBOS Phys. Rev. C72, 031901

x10

x3xd>>xAuxd<<xAu

More central d+Au produces more “bulk”

going with Au

Is it purely a parton-level effect? Or is there more to it?

Rapidity Matters…


Large Dh Correlations

First observation of long – range ridge correlations at RHIC!


BBC

μ μe

Single leptons from heavy flavor decays

Qualitatively consistent with

expectation: Au-going enhanced d-going decreased with centrality

Open Heavy Flavor


PHENIX Phys. Rev. Lett. 107, 142301 (2011)

Trends broadly consistent with more production in Au-going direction. Can we determine

transverse spatial dependence of nuclear modification?

Baseline model --EPS09 with linear thickness dependence,

plus single breakup-cross section -- cannot reproduce

centrality dependence in detail.

Confronting the J/Y


Comparing the J/Y and Y’

Y’ data indicatethat there are effects at shorttimescales that suppress Y’ relativeto J/Y.

Expect increasedsuppression whentime in nucleusis comparable to formation timecc

PHENIX arXiv:1305.5516


Cu+Au: Geometry!

A program that takes advantage of unique capabilities at RHIC:

Find x:

Left/right asymmetric density profile. Odd Harmonics Corona on Au-side

Central collisions No corona on Cu-going

side


Harmonic Components

Aneta Iordanova (Wednesday)

Stronger v1, opposite sign from AMPT.

v2 trends as expected


RHIC and LHC

No change in shape across a wide range in center-of-mass energy – driven by geometry!

Jeff Mitchell (Wednesday)


• There’s a lot underway….– Gamma-hadron correlations– Azimuthal HBT– Dileptons with the HBD– Heavy flavor with the VTX/FVTX– …

A lot going on with Au+Au…Suppression of high zT hadronscorrelated with direct photons – another (key) handle on jet quenching

arXiv:1212.3323


Run-13, Spin, and the W

156 pb-1

Ming Liu (Tuesday)Hubert van Hecke (Thursday)

Data production underway – expect to analyze Run-13 500 GeV data during SpinFest @ RIKEN in July


• RL syst. uncert. O(10-3) • Run9 Stat uncert. O(10-3)BUT • Forward asymmetry O(10-4) (expected)• On disk already: FOM 50x greater than run9, so new stat error will be O(10-4) • RL syst. uncert. hopefully also gets to O(10-4)

max signal expected from DSSV

Run, s syst

2005, 200 2.5x10-4

2006, 200 7.5x10-4

2009, 200 14x10-4

Relative Luminosity Syst Error History

ALL At Forward Rapidity

Scott Wolin (Tuesday)


The Future• New upgrades ready for new physics!

MPC-EX Upgrade (2015) – spin andCNM physics

The FVTX and VTX – ready for HI measurements in 2014!


• d+A collisions are NOT p+A collisions!– Large intrinsic e2

• RHIC has the unique capability to vary the collision geometry to explore the initial state

p+A: More Geometry Control

He3+Au MC Glauber


Polarized p+A Collisions

Single spin asymmetries can act as a probe of the saturation scale.

A unique capability of RHIC!

2 2 2

2 2

2/

2h sp

h sA

pA hP QspN

pp hN sAP Q

QA eA Q

RL

RLN PA

1

Right

Left

Qsp2 = (1.0 GeV)2

QsA2 = (2.5 GeV)2

= 0.16 GeV

• Dependence of QsA on A• Combined with other measurements

this can estimate Qsp

Richard Seto (Tuesday)Kang, Yuan: PRD 84, 034019 (2011)


Conclusions• To extract fundamental QCD physics from the QGP at RHIC we will

have to deal with initial state aspects: – Cold Nuclear Matter (nPDF’s)– Finite-size systems (geometry)– Exciting new physics?

• We are now entering a phase where we have detailed measurements that will make this possible!

• Spin measurements are relentlessly constraining the gluon spin

• PHENIX will continue to pursue a broad-ranging, curiosity-driven physics program that takes full advantage of the flexibility of RHIC!


BACKUP


Transverse Energy

Transverse energy for Cu+Cu similar to Au+Au at same Npart, but Cu+Au higher. Jeff Mitchell (Wednesday)


Upsilon


Ridge in d+Au


Identified RdAu


Y’/(J/Y)


Template

Documents

Summary of Recent PHENIX Results