Journal Summary on JY in a Quark Gluon Plasma

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Journal Summary on J/Y in a Quark Gluon Plasma

• Graduate Student Matt Cervantes
• Advisor Prof. Saskia Mioduszewski

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Outline

• Relativistic Heavy Ion Collider (RHIC)
• Why QGP and (re)creating the QGP?
• Signatures of a QGP?
• J/Y suppression at SPS
• J/Y enhancement at RHIC
• Upsilon at RHIC
• Conclusion

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Why RHIC for QGP?

• In the Big Bang picture where does QGP fit in?
• QCD predicts a hadronic to plasma phase
  transition!
• Lattice QDC predicts transition at T 170 MeV
  (1012K) corresponding to an energy density 1
  GeV/fm3
• RHIC collisions at 200 GeV during the onset of
  thermal equilibrium are of order 5 9 GeV/fm3 !

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Coll
ision
Au
Au
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• Particles stream out from interaction region!
• The STAR detector captures the colliding event!
• What type of physics happens here?
• Is there a Quark Gluon Plasma created here?
• What are possible signatures of a QGP?
• Particle physics of charmonium in a plasma
• i. Suppression?
• ii.Enhancement?

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QGP event reconstruction

• Direct photons SPS (WA98, NA45, NA50)
• g escapes strong medium unaffected, but 95 of g
  from background processes gt 5 free quark g
  production!
• PT distribution of secondary hadrons Quark
  energy losses while traversing through a medium
  at high PT. Heavy quarks were predicted to be
  less afflicted by medium, but RHIC data showed
  strong heavy quark interactions within the
  medium!
• Relative production rates of strange particles
  Use of known strange formation yields in the
  initial hadron processes vs. the final measured
  strange abundances gt Quark soup !?!
• J/Y dilepton events Dilpton productions include
  qqbar Drell-Yan annihilation, thermal production
  in a hot QGP, and hadronic formation.

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J/Y suppression in a QGP

• In a QGP (anti)charm quarks are screened from
  each other and pair up with up and down quarks to
  create familiar D mesons (open charm event)
• J/Y formation is suppressed (matsui,satz)
• J/Y dilepton decay channels are feasible for
  event reconstruction

(matsui,satz)
(NA50)
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J/Y enhancement at RHIC

• Charm cross sections at RHIC are greater than SPS
  due to increased run energy.
• Increased initial charm production and an
  increased chance to thermalize at RHIC creates
  more charmonium events!
• i.e. J/Y production still suppressed via
  deconfinement, while a
• thermal enhancement mechanism drives up J/Y
  formation!
• Thermal J/Y models take enhancement and
  suppression to conspire and possibly negate
  observable effects in J/Y data!
• How does this thermal enhancement modeling fit
  the SPS data?
• SPS data with enhancement inspired models fit the
  measured J/Y yields very well! How about fitting
  the RHIC data?

(Grandchamp, Rapp)
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Upsilon at RHIC

• How about quarks heavier than charm?
• Can RHIC produce the bottom quark? Yes!
• Smaller cross section but RHIC can produce!
• Hundreds of Upsilon to electron decays/year!
• Can STAR detector read them out? Yes!
• Detector upgrades record few hundred/year!
• How will the suppression or enhancement mechanism
  behave for bottom in a QGP?
• Theory predicts suppression mechanism again!
  Enhancement via thermalzation suppressed due to
  heaviness of the bottom quarks!

(Grandchamp, Rapp, Lumpkins, van Hees, Sun)
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Conclusion

• The RHIC experiment at BNL looks like a promising
  place for the production of a Quark Gluon Plasma.
  
• Multiple analysis techniques are implemented in
  the search for the Quark Gluon Plasma.
• J/Y suppression and enhancement modeling looks
  promising.
• Upsilon measurements at RHIC are needed!
• Measuring J/Y final state yields and the proposed
  Upsilon suppression would be complimentary
  measurements for possible Quark Gluon Plasma!