Christina Markert 23 rd WWND Montana, Big Sky, Feb 12-17 1 Resonance production in jets Christina Markert University of Texas at Austin Motivation Resonance

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


Lifetime of nuclear medium

TchemicalTchemical

t ~ > 4 fm/cresonances

t ~ 10 fm/c2 particle correlation Partonic phase < 6 fm/c


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


Resonance suppression in central collisions

Phys. Rev. Lett. 97 (2006) 132301

e-Print Archive: nucl-ex/0604019

Resonances from late decay


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


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.


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 +


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


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)


(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)


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 ?


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


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?


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


(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 !


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


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*, )


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

Documents

Christina Markert 23 rd WWND Montana, Big Sky, Feb 12-17 1 Resonance production in jets Christina Markert University of Texas at Austin Motivation Resonance