a weak interaction probe at forward rapidity daniel jumper university of illinois at...
TRANSCRIPT
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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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!