Highlights from STAR at QM2006

1
Highlights from STAR at QM2006
James Dunlop for the STAR Collaboration
(Brookhaven National Laboratory)
2
Outline

• Single particle spectra with PID
• Partonic species dependence of jet quenching ?
• Recombination at intermediate pT ?
• Correlations, correlations, correlations
• Medium itself HBT, v2
• Response of jet to medium zT distributions
• Response of medium to jet
• Elongation along h the Ridge
• Conical emission 2- and 3- particle correlations
• The future RHIC II and penetrating probes
• Upsilon in pp
• Direct g-hadron correlations

3
The STAR Detector
Large acceptance 2? coverage at mid-rapidity
Magnet Coils Central Trigger Barrel
(CTB) ZCal Time Projection
Chamber (TPC) Year 2000
Barrel EM Cal (BEMC) Silicon Vertex Tracker
(SVT)Silicon Strip Detector (SSD) FTPCEndcap
EM CalFPD TOFp, TOFr FPD Year 2001
PMD
Future upgrade Time of Flight, DAQ1000, Heavy
Flavor Tracker, Muon Telescope Detector
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Grey Probes and Jet Quenching

• Problem interaction with the medium so strong
  that information lost Black
• Significant differences between predicted RAA,
  depending on the probe
• Experimental possibility recover sensitivity to
  the properties of the medium by varying the probe

Wicks et al, nucl-ex/0512076
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Hard Probes p0s and g in STAR

• direct photons and dAu
• double ratio
• (?incl/?0) / (?decay/?0) 1 ?dir/ ?decay
• direct g signal consistent with NLO pQCD
• baseline results for AuAu analysis
• No discrepancy between STAR PHENIX.

• EMCal ?0s in pp
• preliminary result from subset of year 5 data
• good agreement with pQCD KKP fragmentation
• disfavors Kretzer FFs

See Talk by Martijn Russcher
6
Gluon contribution factor to hadrons

• q jets or g jets ? gluon jet contribution to
  protons is significantly larger than to pions at
  high pT in pp collisions at RHIC pbar/? lt 0.1
  from quark jet fragmentation at low beam energy .
  STAR Collaboration, PLB 637, 161 (2006).
• From Kretzer fragmentation function, the g/q jet
  contribution is similar to AKK. S. Kretzer, PRD
  62, 054001 (2000).

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Particle ratios in 200 GeV AuAu
gluon jet
quark jet
quark jet

• At pTgt5 GeV/c at RHIC at 200 GeV
• p(pbar)/? are larger than the ratios from quark
  jet.
• Expectation pbar/? (AuAu) lt pbar/? (dAu, pp).
  (X.N. Wang, PRC 58, 2321, (1998))
• p(pbar)/? (AuAu) p(pbar)/? (dAu, pp). ? new
  experimental phenomena R.J. Fries et al., PRC 68,
  044902 (2003) R.C. Hwa et al., PRC 70, 024905
  (2004) DELPHI Collaboration, Eur. Phy. J. C 5,
  585 (1998), Eur. Phy. J. C 17, 207 (2000) W. Liu
  et al., nucl-th/0607047.

STAR Collaboration, PRL 97 (152301) 2006
? B. Mohantys talk(2.2)
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Energy dependence of RAA (RCP)
Steeper initial jet spectra ? Or Color charge
dependence ? At same pT 3 difference in
xT. Q. Wang and X.N. Wang, PRC 71, 014903 (2005)
At 1.5lt pT lt 6 GeV/c RCP(ppbar) gt RCP(?) At
pTgt6 GeV/c, RCP(ppbar) RCP(?) Similar to 200
GeV AuAu collisions.
? B. Mohantys talk(2.2)
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dsNNcc/dy from pp to AA

• D0, e, and µ combined fit
• Advantage Covers 95 of cross section
• Mid-rapidity dsNNcc/dy vs Nbin
• sNNccfollows binary scaling
• Charm production from initial state (as expected)
• Higher than FONLL prediction in pp collisions.

See Talk by Chen Zhong
10
RAA of Charm/Beauty

• Non-photonic electrons strongly suppressed
• Major issue for jet quenching, especially if B
  contribution large
• But, B contribution highly uncertain

STAR, submitted to PRL
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Can we tell how much beauty?

• Use e-h Correlation
• Large B mass compared to D
• Semileptonic decay e gets larger kick from B.
• Broadened e-h correlation on near-side.
• Extract B contribution
• Use PYTHIA shapes
• Con Model dependent
• Pro Depends on decay kinematics ?well described
• Fit ratio B/(BD)

See Talk by Xiaoyan Lin
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B contribution to NP electrons vs. pT

• Fit e-h correlation with PYTHIA Ds and Bs
• Non-zero B contribution
• Contribution consistent with FONLL
• Model dependent (PYTHIA)
• Depends mainly on kinematics of D/B decay (not on
  Fragmentation).
• Dominant systematic uncertainty
• photonic background rejection efficiency
• Additional uncertainties under study

Beauty !
pp 200 GeV
See Talk by Xiaoyan Lin
13
v2 of strangeness hadrons and nuclei in 200 GeV
AuAu collisions
STAR preliminary
? H. Lius talk(3.4)

• Intermediate pT (0.7ltpT/nlt2GeV/c)
• KS K ? ? ? ? v2 follow NQ scaling.
• The centrality dependence of v2 similar to
  minbias.
• Heavy particle d follows A scaling, 3He follows
  A scaling at low pT, maybe deviate at higher
  pT?need more statistics.

• Y. Bais talk (KS???)(2.4)
• X. Dongs poster (K)(75)

• S. Blyths talk (?)(3.1)

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Energy dependence of particle composition
STAR preliminary

• In 62 and 200 GeV AuAu collisions
• ?/KS ratio similar peak positions.
• p(pbar)/? ratios similar shapes at pTgt2 GeV/c.

system size dependence? B. Mohantys talk(2.2)
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?-h correlations

• _
• if O sss (f ss) at intermediate pT come mostly
  from TTT (TT)
• ?No near side correlation!
• ?Not consistent with data.
• Same-side yield ?0
• Omegas with pT less than 4.5 GeV/c contain
  non-thermal
• s-quarks made in jets?
• ? ? ? - h correlations are similar

R. C. Hwa et al., nucl-th/0602024.

• J. Bielcikovas talk(3.1)

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Discussion recombination/coalescence model
STAR preliminary

• Differences between data and current models
• The p(pbar)/? ratios in energy dependence at
  pTgt2 GeV/c.
• R.J. Fries et al., PRC 68,
  044902 (2003).
• The O/? ratio at pTgt4 GeV/c.
• R. C. Hwa et al.,
  nucl-th/0602024.
• The O-h correlation with 2.5ltpT(trigger)lt4.5
  GeV/c
• and 1.5ltpT(associate)ltpT(trigger)
  GeV/c. R. C. Hwa et al., nucl-th/0602024.

? B. Mohantys talk(2.2)
? S. Blyths talk(3.1)

• J. Bielcikovas talk(3.1)

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Correlations

• RHIC 10-1 to 10-3 level
• Multiple samples
• Multiple probes
• Model dependence in separation of sources

• WMAP 10-5 level
• One sample
• Only photons
• Well-defined separation of sources

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HBT measurement
New direction
imaging vs Abeam
?(1530)
mT scaling for space momentum correlation

• D. Dass poster(21)

• P. Chaloupkas poster(106)
• R. Witts talk(3.1)

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Elliptic flow and its fluctuation
Consistent v2/? scaling for all energies and
collision systems.

• S. Voloshins talk(2.4)

First measurement of v2 fluctuation. ?v2/ltv2gt
36 observed.
central

peripheral

• P. Sorensens talk(2.4)

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Dh-Df Correlations Background

• Near-side long range correlation in ??
• STAR, nucl-ex/0509030
• near side ridge
• How do structures, yields, evolve
• Centrality, kinematics (wide pt ranges), particle
  identification?
• Little guidance from theory data driven approach

Phys. Rev. C73 (2006) 064907
mid-central AuAu pt lt 2 GeV
Dr/vrref
0.8lt pt lt 4 GeV nucl-ex/0607003 See Poster by Ron
Longacre
3 lt pT(trig) lt 6 GeV2 lt pT(assoc) lt pT(trig)
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Dh-Df Component Picture
3ltpt,triggerlt4 GeV pt,assoc.gt2 GeV

• Study near-side yields
• Study away-side correlated yields and shapes
• Components
• near-side jet peak
• near-side ridge
• v2 modulated background

AuAu 0-10 preliminary
Strategy Subtract ?? from ?? projection
isolate ridge-like correlation Definition of
ridge yield ridge yield JetRidge(???) ?
Jet(??) Can also subtract large ??.
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The h Ridge Jet yield vs Centrality
3ltpt,triggerlt4 GeV pt,assoc.gt2 GeV
See Talk by Jörn Putschke
AuAu 0-10 preliminary

• Jet yield constant
• with Npart

pp. low pT Number corr.
AuAu. low pT pT corr.
Reminder from pTlt2 GeV h elongated structure
already in minbias AuAu f elongation in p-p ? to
h elongation in AuAu.
Dr/vrref
PRC 73, 064907 (2006)
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L,K0s Near-side associated yield vs centrality,
AuAu
Charged hadrons ridge yield increased vs.
Npart L,K0s both have increase of near-side yield
with centrality in AuAu L, K0s ratio of yields
in central AuAu/dAu 4-5 ridge yield of K0S lt
ridge yield of L -gt ridge yield increases with
centrality -gt jet yield is constant vs Npart
same yield as in dAu
See Talk by Jana Bielcikova
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Central AuAu Ridge, Jet Yield vs pT, trig pT,
assoc
pt,assoc. gt 2 GeV
Central
Jet spectrum much harder than inclusive gets
harder w/ increasing pt,trigger Ridge spectrum
close to inclusive independent of pt,trigger
Ridge yield constant (slightly decreasing) vs.
pT trig
Ridge Persists up to highest pT trig
See Talk by Jörn Putschke
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Near-side zT Distributions Jet

• Measure hadron triggered fragmentation functions
• Dh1,h2(zT)
• zTpTassoc/pTtrig
• Similarity between AuAu and dAu after ridge
  subtraction

Are the AuAu results with the ridge subtracted
the same as dAu, EVEN at low pT?
See Talk by Mark Horner
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Near-side zT Distributions Jet

• Measure hadron triggered fragmentation functions
• Dh1,h2(zT)
• zTpTassoc/pTtrig
• Ratio AuAu/dAu
• Similarity between AuAu and dAu after ridge
  subtraction

• 8ltpTtriglt15 GeV/c
• STAR PRL 97 162301

Near-side zT distributions similar to dAu no
50 dilution from thermal coalescence triggers?
Phys.Rev. C70 (2004) 024905
See Talk by Mark Horner
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Away-Side pTtrig Dependence

• Away-side
• Structures depend on range of pT.
• becomes flatter with increasing pTtrig
• yield increases

1.3 lt pTassoc lt 1.8 GeV/c
AuAu 0-12
Central contribution to away-side becomes more
significant with harder pTtrig gt fills dip
See Talk by Mark Horner
6.0 lt pTtrig lt 10.0 GeV/c
4.0 lt pTtrig lt 6.0 GeV/c
3.0 lt pTtrig lt 4.0 GeV/c
0-12
Away side
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Away-side zT Distributions

• High zT for hard triggers shows standard
  suppression (0.2)
• Larger yields seen at low zT or low pTtrig
• bulk response
• Deviation from suppression depends on pTtrig

2.5 lt pTtrig lt 4.0 GeV/c never reaches the
0.25?0.06 IAA away-side suppression for pTtriggt8
GeV/c (STAR PRL 97, 162301)
See Talk by Mark Horner
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Correlation from FTPC to MTPC
Trigger 3ltpTtriglt4 GeV/c, A.FTPC 0.2ltpTassoclt
2 GeV/c, A.TPC 0.2ltpTassoclt 3 GeV/c
See Talk by Levente Molnar
2.7lt?assoclt3.9
AuAu 0-10 AuAu 0-5
AuAu 60-80
STAR Preliminary
STAR Preliminary
Near-side correlation consistent with
zero Away-side correlations are very
similar! Energy loss picture is the same for mid-
and forward h? Need quantitative calculations for
correlations analyses!
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Hard-soft correlations

• M. Horners talk(3.2)

• Hard-soft away-side spectra approaching the
  bulk.
• Mach-cone shock waves a fast thermalization
  mechanism through dispersing energy into
  collective modes of shock waves.

STAR Collaboration, PRL 95,152301 (2005)
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Three particle correlation

• Two Analysis Approaches
• Cumulant Method
• 1) Unambiguous evidence for three particle
  correlations.
• Jet-Flowbackground Method
• 1) Within a model dependent analysis,
  evidence for conical emission in central AuAu
  collisions

pTtrig3-4 GeV/c pTassoc1-2 GeV/c

• C. Pruneau s talk(1.3) ? J. Ulerys poster(44)

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RHIC II Benefits of increased luminosity
hadron
Previous Au Run, year 4
photon

• Penetrating probes need higher luminosity
• g-jet precision studies of jet quenching
• Upsilon precision studies of screening length

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More Beauty ? signal in pp

• ee- Minv
• Unlike-Sign Pairs
• Like-Sign Pairs

STAR Preliminary pp 200 GeV
STAR Preliminary pp 200 GeV ee- Minv Background
Subtracted

• Large dataset sampled in Run VI
• Luminosity limited trigger
• Analyzed 5.6 pb-1, with corrections.
• Measure ?(1s2s3s) ds/dy at y0

See Talk by Pibero Djawotho
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Mid-rapidity ?(1s2s3s) Cross section
STAR Preliminary pp 200 GeV
Counts
ds/dy (nb)
y

• Integrate yield at mid-rapidity ylt0.5
• ?(1s2s3s) BR ds/dy
• 91 28 stat 22 syst pb-1 (Preliminary)
• Consistent with NLO pQCD calculations at
  midrapidity.
• Trigger ready for next run and RHIC II
  luminosity limited

See Talk by Pibero Djawotho
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Towards g-jet (g,p0)-h Df Correlation analysis
pp
p0 Mixed Photon
Use shower-shapes in EMC Create two
samples Enriched photon sample (mix g,
p0) Enriched p0 sample (almost pure
p0) Reduction in near angle peak in Photon
sample Away-side yields only slightly
reduced Effect more prominent for larger Ettrigger
See Talk by Subhasis Chattopadhyay
36
Spectra for g-tagged Events
Use g-enriched sample plot away-side pT-spectra
for photon-tagged events Matches charged hadron
spectra in direct photon events from HIJING.
Promising for future g-jet studies RHIC II
See Talk by Subhasis Chattopadhyay
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Summary

• Single particle spectra with PID
• Partonic species dependence of jet quenching ?
• Recombination at intermediate pT ?
• Correlations, correlations, correlations
• Medium itself HBT, v2
• Response of jet to medium zT distributions
• Response of medium to jet
• Elongation along h the Ridge
• Conical emission 2- and 3- particle correlations
• The future RHIC II and penetrating probes
• Upsilon in pp
• Direct g-hadron correlations

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Backup
39
STAR electrons

• Discrepancy between STAR and PHENIX
• Investigated method to estimate Photonic
  background. No issues found.
• Reanalyzed from scratch
• pp results change by 25
• dAu results change by 10
• AuAu results do not change
• Within systematics
• Still difference btw. STAR PHENIX
• RAA still slightly below most cb calculations.
• Future low material run
• Improve uncertainty on background
• Issue remains no information on contribution
  from beauty.

• STAR AuAu 0-5

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STAR QM2006 parallel talks

• J.H. Chen --- Spin alignment of vector mesons
  (K, ?) in AuAu and pp collisions at 200 GeV.
• H. Liu (3.4) --- Yields and elliptic flow of
  d(dbar) and 3He(anti-3He) in AuAu collisions at
  200 GeV.
• G. Wang (3.4) --- Incident-energy and system-size
  dependence of directed flow.
• Y. Bai (2.4) --- v2, v4 centrality, pT and
  particle-type dependence in AuAu collisions at
  RHIC
• I. Selyuzhenkov (3.4) --- Global polarization of
  Lambda hyperons in AuAu collisions at RHIC
• S. Voloshin (2.4) --- Energy and system size
  dependence of elliptic flow and v2/e scaling
• J. Putschke (1.3) --- Near-side ?? correlations
  of high-pT hadrons from STAR
• B. Mohanty (2.2) --- Properties of particle
  production at large transverse momenta in CuCu
  and AuAu collisions at RHIC energies
• M. Horner (3.2) --- Low and intermediate pT
  azimuthal di-hadron correlations from 200 GeV
  AuAu collisions measured in STAR
• J. Bielcikova (3.1) --- High pT azimuthal and
  pseudorapidity correlations with strange baryons
  and mesons at RHIC
• X. Lin (2.2) --- Study B and D contributions via
  azimuthal correlations between non-photonic
  electrons and charged hadrons
• C. Zhong (2.1) --- Scaling of charm integrated
  cross section and modification of its transverse
  momentum spectra in dAu and AuAu collisions at
  RHIC
• R. Witt (3.1) --- ?0(1530) production in heavy
  ion collisions and its implications for
  ?t(therm-chem)
• S. Blyth (3.1) --- A measurement of the
  centrality dependence of the N(?)/N(?) ratio and
  ? anisotropic flow
• P. Djawotho (3.1) --- Quarkonium production at
  STAR
• S. Chattopadhyay (3.2) --- Azimuthal ?-charged
  hadron correlations in dAu and pp collisions
  from STAR at 200 GeV
• M. Russcher (3.3) --- Direct photon production in
  pp and dAu collisions at 200 GeV from STAR
• P. Sorensen (2.4) --- First measurements of
  elliptic flow fluctuations
• C. Pruneau (1.3) --- Is there a Mach-cone?
  Three particle azimuthal correlations from STAR

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STAR QM2006 posters

• P. Chaloupka --- ?-? correlations in dAu and
  AuAu collisions at STAR
• S. Das --- Strangeness fluctuations at RHIC
• T. Tarnowsky --- Energy and system size
  dependence study of percolation phase transition
• R. Raniwala --- Elliptic flow of inclusive
  photons and charged particles in CuCu collisions
  at 200 GeV
• J. Ulery --- Are there Mach cones in heavy ion
  collisions? Three particle azimuthal correlations
  in STAR
• J. Bouchet --- Performance studies of the silicon
  detectors in STAR towards microvertexing of rare
  decays.
• M. Cosentino --- Upsilon measurement in STAR
• A. Iordanova --- System size dependence of
  freeze-out properties at RHIC
• D. Das --- Identical Meson Interferometry in STAR
  Experiment
• X. Dong --- K production in AuAu collisions at
  RHIC
• H. Gose --- Proton femtoscopy in STAR
• A. Knospe --- Strangeness and heavy flavor
  production
• G. Lin --- The inclusive photon and charged
  particle v2 at 200 GeV in AuAu and CuCu
  collisions.
• R. Longacre --- ???? scaled correlation signals
  which increase with centrality of AuAu
  collisions at 200 GeV
• T. Nayak --- Net charge fluctuations using high
  order cumulants
• P. Netrakanti --- Mechanism of particle
  production in pp and dAu collisions
• M. Shao --- A study of the intrinsic time
  resolution of MRPC used in STAR-TOF
• S. Monika --- Energy and system size dependence
  of photon production
• B. Srivastava --- Understanding the particle
  production mechanism with correlation studies
  using long and short range correlations and the
  balance function

42
STAR Collaboration
U.S. Labs Argonne, Lawrence Berkeley,
and Brookhaven National Labs U.S. Universities
UC Berkeley, UC Davis, UCLA, Caltech,
Carnegie Mellon, Creighton, Illinois-Chicago,
Indiana, Kent State, MIT, MSU, CCNY, Ohio State,
Penn State, Purdue, Rice, Texas AM, UT Austin,
Washington, Wayne State, Valparaiso,
Yale Brazil Universidade de Sao
Paolo China IHEP - Beijing, IPP - Wuhan,
USTC, Tsinghua, SINAP, IMP Lanzhou Croatia
Zagreb University Czech Republic
Nuclear Physics Institute England University
of Birmingham
France Institut de Recherches Subatomiques
Strasbourg, SUBATECH - Nantes Germany Max
Planck Institute Munich University of
Frankfurt India Bhubaneswar, Jammu, IIT-Mumbai,
Panjab, Rajasthan, VECC Korea Pusan Natl
University Netherlands NIKHEF Poland Warsaw
University of Technology Russia MEPHI
Moscow, LPP/LHE JINR Dubna, IHEP Protvino
Thanks!
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Df Correlation, strange particle triggers, AuAu
200 GeV
See Talk by J. Bielcikova
trigger baryon/meson baryon/antibaryon
Selection criteria 3.0 GeV/c lt pTtrigger lt 3.5
GeV/c 1 GeV/c lt pTassociated lt 2 GeV/c h lt 1
STAR preliminary
STAR preliminary
STAR preliminary
STAR preliminary
correlation functions before elliptic flow
subtraction
correlation functions after elliptic flow
subtraction syst. error due to v2 uncertainty
25
44
Direct photons for correlation analysis
Standard methods used for extraction of photons
Statistical method by Reconstruction of
inclusive photons Subtract photons from decay
of p0 , h etc. Cannot be used for
correlation. Method Enhance g using difference
in shower shapes.. Compare correlation
functions between g-enriched (narrow EM
showers) p0-enriched (broader EM
showers) mixed
PHOTON
p0
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Associated pT Dependence

• Centrality 0 - 12
• Associated pT (rows)
• 0.3 0.8 GeV/c
• 0.8 1.3 GeV/c
• 1.3 1.8 GeV/c
• 2.0 4.0 GeV/c
• Triggers (columns)
• 2.5 4.0 GeV/c
• 3.0 4.0 GeV/c
• 4.0 6.0 GeV/c
• 6.0 10.0 GeV/c
• Detailed cases
• 3rd row
• right column

pTassoc
pTtrig
see talk by M. Horner
7
46
Heavy Flavor Production

• e-h Correlations
• Understanding features in heavy quark
  measurements requires experimental measurement of
  B and D contributions.
• First try use non-photonic electron
  correlations.
• See talk from Xiaoyan Lin

47
v1 measurement
v1 depends on energy, not on system size.

• G. Wangs talk(3.4)
  

v4/v22 measurement, see Y. Bais talk(2.4)

48
Fluctuation and freeze-out dynamics at RHIC
STAR preliminary
K/? fluctuation similar in 62 and 200
GeV Positive long range ?? correlation
observed ? B. Srivastava poster(101)
STAR Preliminary

• S. Dass poster(107)

Tch (GeV)
Energy scan to map out the critical point by
measuring K/?, p/? fluctuation and identified
particle spectra in the future.

• A. Iordanovas poster(04)

µB (MeV)
49
Soft physics measurements vs dNch/d?

• A. Iordanovas poster(04)

Tkin,ltpTgt, HBT Radii are strongly correlated with
(dNch/d?).
nucl-ex/0505014 Lisa et al.

• D. Dass poster(21)

50
Summary

• EOS and thermalization
• 1) Significant v2 fluctuation
• 2) 3 particle jet correlation evidence for
  conical emission.
• Coalescence
• 1) Similar shape of p(pbar)/? ratios at
  pTgt2 GeV/c between 62 and 200 GeV
• 2) The ?/? ratio peaks at pT4 GeV/c
• 3) Significant ?-h correlation at
  intermediate pT.
• Jet quenching parton energy loss
• The common suppression of pbar and pion ?
  new experimental phenomena

• Energy and system size dependence of v2,
  fluctuation
• Three particle correlation
• ? K p at low pT, light nuclei production
• Correlation and fluctuation
• K, ?, KS, ?, ?, ?, ?, K, p v2 and RCP
• Baryon/meson-charged hadron correlation
• PID spectra at high pT
• Pbar and pion Casimir factor CA/CF9/4
• Charm and bottom dead cone
• Energy dependence of identified particle
  production
• Thanks to the STAR Collaboration!