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This
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is
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the
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wiki
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for
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the
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W
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and
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Z
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analyses
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using
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the
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Barrel
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Electromagnetic
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Calorimter
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(BEMC)
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at
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STAR.
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The
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goal
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of
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the
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analyses
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is
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to
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measure
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a
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cross
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section
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and
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single
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helicity
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asymmetry,
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A_L.
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Introduction
Single spin asymmetries in W and Z production can be used to probe the spin structure of the proton.
Detector
STAR detector at RHIC is used to reconstruct charge and neutral EM particles from pp collisions at sqrt of 500 GeV.Signal
Wiki Markup [Pythia] event generator is used to produce pp events yielding
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[W-bosons
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]. An example of W-event which decay to electron and neutrino is shown on the plot below. Requirement has been imposed on this event to deposit at least 20 GeV of ET in EMC in single cluster located at phi \[80,100\] deg and pseudo-rapidity \[-0.8,+0.8\]
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Backgrounds
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- Most
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- common
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- type
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- of
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- result
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- of
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- collision
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- of
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- 2
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- protons
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- is
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- a
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- pair
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- of
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- jets.
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- Below
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- you
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- can
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- see
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- and
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- example
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- of
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- such
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- QCD
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- background
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- event
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- passing
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- the
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- same
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- criterium
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- of
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- depositing
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- at
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- least
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- 20
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- GeV
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- ET
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- in
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- localized
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- cluster.
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Below
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- are
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- example
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- of
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- STAR
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- response
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- to
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- W-event
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- (left)
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- and
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- QCD-event
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- (right)
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Gallery