Resonance production in heavy-ion collisions at STAR
description
Transcript of Resonance production in heavy-ion collisions at STAR
![Page 1: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/1.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 1
Resonance production in heavy-ion collisions at STAR
Christina MarkertUniversity of Texas at Austin
• Motivation• Resonances Hadronic phase (system size/energy) Chiral symmetry restoration (jets)• Conclusion
![Page 2: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/2.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 2
Lifetime of nuclear medium 200 GeV Au+Au
TchemicalTchemical
t ~ 3-5 fm/cresonances
t ~ 10 fm/c2 particle correlation Partonic phase ~ 5-7 fm/c
Phys. Rev. Lett. 97 (2006) 132301
![Page 3: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/3.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 3
Hadronic re-scattering and regeneration
Life-time [fm/c] :K(892) = 4.0 =(1520) = 13 (1020) = 45
Depends on:• hadronic phase density • hadronic phase lifetime
time
signal lost
signal measured late decay
signal measured
signal measuredearly decay
che
mic
al fr
eeze
-o
ut
p
pp
kin
etic
fre
eze
-out
re-scattering
regeneration
e+
e-leptonic decay
hadronic decay
![Page 4: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/4.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 4
System size and energy dependence
increasing centralitylarger system size
Au 197
Cu 64
smaller nucleus Smaller system size
lower energy
200 GeV
62 GeV
compare to number ofproduced charged
particlesdN/dy
![Page 5: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/5.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 5
Resonance suppression (system size dependence)
Suppression scales with dNch/dy ~ system size
STAR preliminary
[1] P. Braun-Munzinger et.al.,PLB 518(2001) 41, priv. communication[2] Marcus Bleicher and Jörg Aichelin Phys. Lett. B530 (2002) 81. M. Bleicher and Horst Stöcker J. Phys.G30 (2004) 111.
Phys. Rev. Lett. 97 (2006) 132301 Phys. Rev. C71 (2005) 064902See S. Dash SQM2007 statistical errors only !
Regeneration/Rescattering cross section:p)
Life-time [fm/c] :K(892) = 4.0 =(1520) = 13 (1020) = 45
STAR Preliminary
A Lordanova SQM2007
[2][1]
![Page 6: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/6.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 6
Resonance suppression (energy dependence)
STAR preliminary
Phys. Rev. C71 (2005) 064902nucl-ex/0703033See S. Dash SQM2007
Life-time [fm/c] K(892) = 4.0 (1020) = 45
STAR preliminary
M. Bleicher et al.
statistical errors only !
Less re-scattering at lower energies in peripheral collisionsSame volume but,• Lower density smaller interactions cross section?• Shorter hadronic lifetime less hadronic interactions ?
![Page 7: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/7.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 7
Regeneration might increase elliptic flow
C. Nonaka, et al.,Phys.Rev.C69:031902,2004
Data suggest small regeneration for K* (need smaller errors !)
minbias 200 GeV Au+Au
Partonic resonance generation:Number of Constituent Quark (NCQ) scaling at intermediate pT (meson NCQ = 2)
Hadronic resonance (re)generation:Regenerated resonances–final state interactions NCQ = 4 (* = + =2+2)
Phys. Rev. C71 (2005) 064902
Recombination model
![Page 8: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/8.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 8
Mass shift and width broadenings are predicted as influence of medium on resonance spectral function, e.g.:
For baryonic and strange resonances
M.F.M Lutz (SQM 2001) J.Phys.G28:1729-1736,2002
M.F.M Lutz, E.E. Kolomeitsev, Nucl.Phys.A755:29-39,2005. hep-ph/0501224
For mesonic resonances Ralf Rapp (Texas A&M) J.Phys. G31 (2005) S217-S230
(1520) and (1385) resonances decay channel change
M. Kaskulov et al., nucl-th/0509088
Resonance in a medium (nuclear matter)
![Page 9: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/9.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 9
Resonances from jets
near-side
STAR Preliminary
near
away
Study Chiral Symmetry Restoration by comparing resonance production in event classes based on azimuthal distribution:
We expect high pT resonances from the away side jet to be medium modified due to the high density and temperature of the partonic and pre-equilibrium hadronic medium
arXiv:nucl-ex/0706.0724
![Page 10: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/10.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 10
Formation of hadronic resonances (from jets) in a chiral medium
side 1
side 2
near
away
Low pt High pt
Near side No medium or late hadronic medium
No medium
Away side Late hadronic medium Partonic or early hadronic medium (depend on formation time) CSR ?
Side 1 & 2 Late hadonic medium Early hadronic medium
Formation time arguments:a.) General pQCD:Formation time [fm/c] ~ pT [GeV]Formation time [fm/c] ~ 1/massb.) Specific string fragmentation (PYTHIA) formalism:Gallmeister, Falter, PLB630, 40 (2005)Intermediate pT resonances form earlyc.) Vitev et al. (hep-ph/0611109): High pT heavy particles and resonances form early
Need to determine the right momenta for trigger and resonance particle
![Page 11: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/11.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 11
First attempt(1020) reconstruction from jets
M inv (K+ K-)
M inv (K+ K-)
Trig
ger/
Eve
nt
Number of triggers
• Trigger particle: hadron pT > 4.0 GeV • Associated particle: resonance (1020) <pT>~ 0.9 GeV
~95% of events have on trigger particle
(1020)
charged hadrons200 GeV Au+Au
![Page 12: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/12.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 12
(1020) from same/away side in/out of plane
side1
side2
near
away
Systematic errors are ~ 10%
51385±2369
64498±2400 54893±2378
61043±2394
No mass shift or width broadening
visible
Yield away/same1.26±0.19
side2
side1 near - side
away- side
![Page 13: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/13.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 13
Hadron - resonance correlation in Au+Au
of h-(1020) – C • h-(1020) mixed event
Pythia 75M events p+p 200 GeV only phi (no background from K+K combinations)
QM2006 M.Horner
Pythia p+p
STAR preliminary
ZYAM = zero yield at minimum
Hadron trigger pT > 4 GeV (1020) <pT > ~ 0.9 GeV ( need higher pt )
Not corrected for acceptanceSystematic BG normalization error not included
Not corrected for v2
![Page 14: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/14.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 14
Time of Flight upgrade detector
STAR: Time of Flight detector upgrade:• PID at higher momentum • Electron hadron separation• Installation completed in 2-3 years
STAR Experiment
|1/β-1|<0.03
J.WU QM2006
TOF
Improves reconstruction of hadronic and leptonic decay channels:K* K+, p*p
ee
![Page 15: Resonance production in heavy-ion collisions at STAR](https://reader035.fdocuments.in/reader035/viewer/2022062314/568148bf550346895db5dc9f/html5/thumbnails/15.jpg)
Christina Markert SQM2007, June 2007, Levoča, Slovakia 15
Conclusions
• Low momentum resonances provide information regarding the lifetime of hadronic stage.
• Re-scattering cross section scales with system size.• Lower collision energy results in less hadronic interactions.
• High momentum resonances from jets could be used as a tool to trigger on early produced resonances and test chiral symmetry restoration
• Need more quantitative theoretical description of formation time of hadronic resonances as a function of mass, momentum and medium density.
• First step: Untriggered 1020) correlation spectrum shows no
evidence of medium modification • Next steps:
• Trigger on high p T (1020)• Reconstruct resonances in jets with shorter lifetime as (1020)
but sufficient statistics (e.g. K*, ).
• New TOF detector will help to study higher pT resonance and leptonic decays.