A Weak

Interaction

Probe at

Forward

Rapidity

FOR PRODUCTION IN POLARIZED AT

PHENIXDaniel Jumper

University of Illinois at Urbana-Champaign

PHENIX Collaboration4 th Joint APS DNP and JPS Meeting

October 9, 2014

Introduction to Proton SpinSea quark spin with the weak interaction

RHIC Polarized Forward at PHENIXResults and Prospects

OUTLINE

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PROTON SPIN

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Proton Spin Decomposition:

for – Gluon spin orbital angular momentum

Current Understanding DIS/SIDIS

, some RHIC

,

WEAK PROBE FOR SEA QUARK SPIN

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More clean and direct access with the weak interaction No fragmentation

functions High

Constraints: Weak parity violation

’s couple to left handed and right handed

Known spin distributions spin tends to be aligned

with proton spin, anti-aligned

𝑊 ±

AT FORWARD RAPIDITY

A fi rst order motivation: At forward rapidity or equations reduce:

It’s not actually this simple! is measured, not Measured asymmetries used in

global fit to extract pdf’s accounting for higher order effects

Proton Constituent Probability Distributions

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SPIN AT RHIC

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at up to 60% polarization“Siberian Snake” Spin Rotators

RECENT RUNS

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Up to 510 GeV

High polarization is important for figure of merit

events are rare at large rapidity

Forward Arms: Trigger and tracking systems targeting these muons (~1.2-2.4) Upgraded highly

selective trigger Developed over the

past decade JSPS and NSF funding

FORWARD AT PHENIX

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FORWARD AT PHENIX

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Signal events dominated by other processes Other sources of muons, “Fake” muons from hadronic

decayMade worse by smearing in tracking detectors

Muonic Signal and Background contributions

Process cross sections vs from simulationsAlso Hadronic “Fake” Muon Background Contribution

Including Smearing

Multivariate analysis technique: Likelihood Ratio Apply a cut to select data

with higher relative signal content

Characterize signal/background ratio of remaining data

Count of remaining data, correct by sig/bkg, effi ciencies, polarization

ANALYSIS TECHNIQUE

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Likelihood Ratio

. . .

RESULTS AND PROSPECT

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2012 preliminary Results 53

Projected 2013 Results Projected error for 200 Actual data taken:

277 Analysis well underway,

preliminary results soon!

Forward asymmetry gives insight to

Extracting this signal is experimentally challenging

Pending results from PHENIX will contribute to a better understanding of sea quark spin

CONCLUSION

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DSSV projected impact of PHENIX and STAR results for