Recent Strangeness and Exotics results from RHIC

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Recent Strangenessand Exotics results from RHIC
Little strokes fell great oaks. Old English
Proverb
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Some of the data
L(1520) (uds)
S(1385) (uus)
More AuAu and CuCu soon to come !
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Baryon density
Mid-rapidity
BRAHMS PRELIMINARY
mb drives the production ratios
Npart lt 20 or low energies?L/L ratios rising
Differences appearing in p-p production
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Collision energy dependencies
AuAu
PbPb
STAR Preliminary

• s-Baryon production is constant at
  mid-rapidity.

• ?s-Baryon rises smoothly at mid-rapidity.

What determines the overall yields?
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Centrality dependence
Redlich et al.
L and X yields in AuAu relative to pp
rises.
Canonical suppression increases with
increasing strangeness
Production volume not well modelled by Npart
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Motivation from h-
PHOBOS Phys. Rev. C70, 021902(R) (2004)
Theres a correlation between dNch/dh and Npart/2
small dotted lines are dNch/dh
npp(1-x)Npart/2 xNbin npp Yield in pp
2.29 ( 1.27) x 0.13
N.B. SPS energy only 17 GeV
If know npp can predict yield at any ?Npart?
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HBT and dNch/dh
HBT radii linear as a function Npart1/3 Even
better in (dNch/dh)1/3 power 1/3 gives approx.
linear scale
Scaling works across a large energy range
nucl-ex/0505014 M.Lisa et al.
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Strangeness and dNch/dh
Look at yields relative to pp
SPS and RHIC data follows same curves as a func.
of dNch/d?
dNch/d? - strongly correlated to the entropy of
the system!
Entropy alone seems to drive much of the soft
physics
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Flavor dependence of scalings
PHENIX Ds
Binary scaling for heavy flavor quark hadrons
Participant scaling for light quark hadrons
Hadrons with strange quarks are add-mixture of
Npart and Nbin
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Spectral distributions
Most Central Collisions

• Temperature Tkinetic is higher for baryons with
  higher strange quark content for Blast-wave fits.
• Spectral shapes are different.

T100 MeV
T132 MeV

• p,K, p lt?Tgt 200 GeV gt 62 GeV Tkin 200
  GeV 62 GeV
• X, W lt?Tgt 200 GeV 62 GeV Tkin 200
  GeV gt 62 GeV

Tkinetic from a Blast-Wave is not same as
the Temperature from a Hydro Model.
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Nuclear modification factors
vsNN200 GeV
Baryon and meson suppression sets in at different
pT .
62 GeV Rcp shows less suppression.
Baryon and meson suppression sets in at same
quark pT. Coalesence/recombination
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Flavor independence of Modification factor?
h- - u and d dominated
e - c (maybe b) dominated
X s quark dominated
No apparent flavor dependence of energy loss
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RAA of strange particles
K, K0s, f and h- all scale similarly
Particles with strange quarks scale differently
to non-strange
Phase space effects dominate out to high pT
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Model explanation
Topor Pop et al. hep-ph/0505210
HIJING/BBar KT 1 GeV Strong Colour
Field qualitatively describes RAA. SCF long
range coherent fields SCF behaviour mimicked by
doubling the effective string tension SCF
controls?qq and qqqq production rates and gs
SCF only produced in nucleus-nucleus collisions
RAA? RCP
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mT scaling
No complete mT scaling
Au-Au Radial flow prevents scaling at low
mT Seems to scale at higher mT
p-p Appears to be scaling at low mT
Baryon/meson splitting at higher mT Gluon jets?
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Strange PID correlations
AuAu 0-5 1.0ltpTAssociatedlt2.0

• ?
• Anti-?
• KS0

pTTrigger
Hint of split between baryons and mesons in near
side yield at high pT Need more stats
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Exotics Pentaquarks
D.S. Carman, Ohio University JLab Users meeting

• The published results on the Q from analysis of
  the g2a data cannot be reproduced in the analysis
  of the high statistics g10 data.
• The statistical significance in the published
  data is a coupling of a statistical fluctuation
  and the underestimate of the background in the
  mass region of 1.54 GeV.

Q ? K n
Clas Statement 6/30/04 Improved analysis of
this data finds that the significance of the
observed peak may not be as large as indicated.
We expect a definitive answer from a much larger
statistics data set that is currently being
analyzed.
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Q and L(1520)
STAR Preliminary d-Au
L(1520)
Same analysis used for both plots
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Analysis continues
If pK peak at 1530 MeV/c2 is real I 1 Must
be q. Recent JLab null result! Yield from
STAR analysis is very small Sensitivity of
other experiments? No signal in 200 GeV pp
(8M) and AuAu (10M). What do these null
observations mean? Production dynamics or
unknown data set bias? Peak a fake?
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Strangelet search in STAR
Use the forward ZDC SMD
Strangelets have high m/z ratio
Acceptance depends on charge
SMD Cluster shapes different
Neutron Cluster
Strangelet Cluster
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Strangelet trigger
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The results so far..
STAR Preliminary
None found.
Upper limits at level of a few 10-6 to 10-7 per
central AuAu collisions are set for mass ? 30
GeV/c2
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Summary

• Have gathered data for a very detailed study.
• Evidence that strangeness production driven by
  the entropy of the system created, not only by
  Npart.
• Evidence of phase space suppression out to high
  pT.
• Starting exporation of strangeness role in
  fragmentation
• Little or no evidence for exotica

The old QGP oak is starting to tremble and
were probing its core
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How does volume affect production?

• Canonical (small system i.e. p-p)
• Quantum Numbers conserved exactly.
• Computations take into account energy to
  create companion to ensure conservation of
  strangeness.
• Relative yields given by ratios of phase space
  volumes
• Pn/Pn fn(E)/fn(E)
• Grand Canonical limit (large system i.e. central
  AA)
• Quantum Numbers conserved on average via
  chemical potential Just account for creation of
  particle itself.
• The rest of the system picks up the slack.

When reach grand canonical limit strangeness
will saturate.
Not new idea pointed out by Hagedorn in
1960s (and much discussed since)
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p-p model calculations
Can EPOS reproduce multiplicity dependence?
Werner Vogelsang
NLO - Nice agreement with K0s, L problematic
Calculations also work for p but not protons
Recent EPOS calculations seem to be working
Agreement due to a very strong soft component
from string fragmentation in the parton ladder
formalism.
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Predictions at higher energies

• Canonical suppression
• increases with decreasing energy

• Canonical suppression increases with increasing
  strangeness

s(Npart) / Npart e s(pp) e gt 1
Enhancement!
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But then at vs 8.8 GeV
NA57 (D. Elia QM2004)

• C to GC predicts a factor 4 - 5 larger X-
  enhancement at vsNN 8.8 GeV than at 17 GeV

Perhaps yields dont have time to reach limit
hadronic system?
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On linear scales
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RAA of Strange Particles
Mesons (h h-, K0s , f) follow similar
trends. Strange baryons dont show
suppression. Rcp ? Raa for strange baryons.
Canonical suppression in pp ?
0-5
STAR Preliminary
STAR Preliminary
s-quark
Ordering with strangeness content!
vsNN200 GeV
Particles with strange quarks scale differently
than non-strange!
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Lots of evidence
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No evidence
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How does volume affect production?

• Canonical (small system i.e. p-p)
• Quantum Numbers conserved exactly.
• Computations take into account energy to
  create companion to ensure conservation of
  strangeness.
• Relative yields given by ratios of phase space
  volumes
• Pn/Pn fn(E)/fn(E)
• Grand Canonical limit (large system i.e. central
  AA)
• Quantum Numbers conserved on average via
  chemical potential Just account for creation of
  particle itself.
• The rest of the system picks up the slack.

When reach grand canonical limit strangeness
will saturate.
Not new idea pointed out by Hagedorn in
1960s (and much discussed since)
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Predictions at higher energies

• Canonical suppression
• increases with decreasing energy

• Canonical suppression increases with increasing
  strangeness

s(Npart) / Npart e s(pp) e gt 1
Enhancement!
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But then at vs 8.8 GeV
NA57 (D. Elia QM2004)

• C to GC predicts a factor 4 - 5 larger X-
  enhancement at vsNN 8.8 GeV than at 17 GeV

Perhaps yields dont have time to reach limit
hadronic system?
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Backgrounds considered and rejected
p0 ? gg ? ee- ee- Same-sign es within the K
and p bands mostly in the low mass region
opening angle cut ? very effective removal
Associated production LK ? pp- K
Neither source produces a narrow peak !
D?pp and using p as K doesnt produce peak in
relevant mass range
Peak seems stable to variations in mtm cuts of
daughters
But still looking at other sources of background
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Exotica Strangelets

• True ground state of baryonic matter -
  stable/meta-stable.
• Low z/A, reduced Coulomb, no fission - No limit
  on size.
• Can grow by absorbing neutrons - new energy
  source.
• Strangelet with Agt1017 (Rgt5 angstrom) will not
  be supported
• by the surface of the earth.
• Strangelets with Mgt2MSUN Will collapse into a
  black hole,
• Strangelets with Mlt2MSUN Will be similar to
  neutron stars.

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Upper Limit
E886 (AGS) Adam Rusek E878 (AGS) Mike
Bennett E864 (AGS) K.Barish, M.Munhoz,
S.Coe, JN E864 (AGS) Z.Xu, G.V.Buren,
R.
Hoverstein NA52(CERN) R. Klingenberg,
K.Pretzel - - - STAR (RHIC)
Z-5
Z5
Upper limits at level of a few 10-6 to 10-7 per
central AuAu collisions are set for mass ? 30
GeV/c2
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Multiplicity dependence
HIJING can only match data with extreme
parameters kT 4 GeV
EPOS results eagerly awaited.