christina markert 23 rd wwnd montana, big sky, feb 12-17 1 resonance production in jets christina...
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Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 1
Resonance production in jets
Christina MarkertUniversity of Texas at Austin
• Motivation• Resonance measurements Time evolution of hadronic phase• Chiral symmetry restoration• Resonances from jets• Summary and a lot of future plans
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 2
Lifetime of nuclear medium
TchemicalTchemical
t ~ > 4 fm/cresonances
t ~ 10 fm/c2 particle correlation Partonic phase < 6 fm/c
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 3
Hadronic re-scattering and regeneration
Life-time [fm/c] : = 1.3++ = 1.7 K(892) = 4.0 =(1520) = 13 (1020) = 45
Depends on:• hadronic phase density • hadronic phase lifetime
time
che
mic
al fr
eeze
-o
ut
signal lost
kin
etic
fre
eze
-out
signal measured late decay
signal measured
rescattering
regeneration
e+
e-
signal measuredearly decay
+
-
signal measured late decay
e+
e-
signal measuredlate decay
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 4
Resonance suppression in central collisions
Phys. Rev. Lett. 97 (2006) 132301
e-Print Archive: nucl-ex/0604019
Resonances from late decay
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 5
Resonance decay product re-scattering
Decay daughters from low pT resonances re-scatter in hadronic phase
Decay daughters from high pT resonances are less affected by hadronic phase
Net shift in <pT>
Resonance signal from early medium• Leptonic decay• High momentum resonance
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 6
Resonance response to medium
Tc
part
on
s
had
ron
s
Baryochemical potential
Temperature
Quark Gluon Plasma
Hadron Gas
T Freeze
Shuryak QM04LHC?
Resonances below and above Tc:
Chiral symmetry restoration Mass and width of resonances
Hadronic time evolution From hadronization (chemical freeze-out) to kinetic freeze-out.
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 7
Chiral symmetry restoration
Ralf Rapp (Texas A&M) J.Phys. G31 (2005) S217-S230
Vacuum At Tc: Chiral Restoration
Measure chiral partnersnear critical temperature Tc (e.g. and a1)
Data: ALEPH Collaboration R. Barate et al. Eur. Phys. J. C4 409 (1998)
a1 +
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 8
Leptonic resonance reconstruction
STAR: Electron hadron separation with Time of Flight upgrade detector
STAR Experiment
Electronics and detector assembling at UT Austin
|1/β-1|<0.03
J.WU QM2006
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 9
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)
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 10
(1520) and (1385) in medium = 10
(1520): ~100 MeV mass shift and (100 MeV width)(1385): ~40 MeV mass shift and (50 MeV width)
Spectral function of statesM.F.M Lutz J.Phys.G28:1729-1736,2002
Resonance in a medium (nuclear matter)
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 11
Resonances from jets to probe chirality
Bourquin and GaillardNucl. Phys. B114 (1976)
T=170 MeV, T=0 Leadinghadrons
Mediumaway
near
• In p+p collisions resonances are predominantly formed in jets. • Comparison of resonances from jets (no medium) with resonances from bulk (medium)
jets ?
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 12
Resonances from jets
In jet –plane
Out of jet-planeIn jet-plane
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 early hadronic medium
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 13
Resonances from jets and formation time
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)
side Late hadonic medium Early hadronic medium
K. Gallmeister, T. Falter.
Phys.Lett.B630:40-48,2005
General pQCD:Formation time [fm/c] ~ pT [GeV]Specific string fragmentation (PYTHIA) formalism:Gallmeister, Falter, PLB630, 40 (2005)Heavier particles form later, Resonances form earlier
Which are the right momenta for trigger and resonance particle?
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 14
First attempt(1020) reconstruction in STAR
M inv (K+ K-)
M inv (K+ K-)
Trig
ger/
Eve
nt
Number of triggers
• 4.5 M Au+Au 0-20% most central data • Leading hadron particle pT > 4.0 trigger/event = 0.12• Associated resonance particle (1020) <pT>~ 0.9 GeV (1020)/event = 0.05
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 15
(1020) from same/away side in/out of plane
side 1
side 2
near
away
In Jet-Plane Same Side near
In Jet-Plane Away Side away
Trigger pT > 4GeV, (1020) <pT>~ 0.9 GeV
All angles
Out of Jet-Plane side1 + side2
No mass shifts or width broadenings visible Expected, since pT of (1020) is small, need to increase f pT
Less signal at the same side compared to away side (20%±10%)
M inv (K+ K-)
M inv (K+ K-)
M inv (K+ K-)
M inv (K+ K-)
Systematic errors not included !
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 16
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
See Jana’s and Betty’s talk
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 17
Conclusion and future plans
• Hadronic low momentum resonances are affected by hadronic interaction medium Measurement provides lifetime between chemical and thermal freeze out• High momentum resonances from jets might be used as a tool to trigger on early produced resonances and test chiral symmetry restoration if they leave the hadronic medium without interaction• Need theoretical description of resonance momentum and medium density when decay occur.• Study p+p and Au+Au data with different pT selections for associated and trigger resonances in hadron-resonance correlations.• Reconstruct resonances in jets with shorter lifetime as (1020) but sufficient statistics (e.g. K*, )
Christina Markert 23rd WWND Montana, Big Sky, Feb 12-17 18
EMCal in ALICE
Without single jet reconstruction only statisticalAnalysis possible.Jet reconstruction Calorimeter necessary
Major advantages at the LHC:-Jet energy known, i.e. measure effect as function of fractional momentum-Enhanced statistics in relevant resonance pt-Range (3-10 GeV/c)-Trigger on quark and gluon jets separately