Jet quenching au RHIC:
résultats expérimentaux

Journée thématique “Jet quenching”

IPN-Orsay, November 14th, 2005

David d’Enterria

LLR – Ecole Polytechnique, IN2P3, Paris

Overview

 “Jet physics” results @ RHIC (w/o full jet reco):

(1) Inclusive high pT spectra, (2) di-hadron φ,η high-pT triggered correlations.

confronted to non-Abelian radiative energy loss in QGP “paradigm”.

 High pT (leading) hadron suppression data in central AA:

1. Magnitude ÞVery dense medium: dNg/dy ~ 1000 (~ dNch/dη). OK

2. Transverse momentum dependence: flat pT . OK

3. Centrality dependence. OK

4. Light-meson species dependence (π0 vs. η). OK

5. Center-of-mass energy dependence (SPS-20 GeV, RHIC-62,200 GeV). OK

6. Non-Abelian radiation. OK

7. Path-length dependence. OK ?

8. System-size (CuCu vs. AuAu) dependence. OK ?

9. Heavy vs. light quark suppression. OK ?

 Modified high pT di-hadron (φ,η) correlations in central AA:

1. Disappeareance of away-side azimuthal dijet peak. OK

2. Enhanced (“volcano”-like) away-side associated yield at lower pT. (?)

3. Broadening of near-side pseudo-rapidity correlations. OK

“Jet quenching” as a QGP signal

Multiple final-state non-Abelian (gluon)

radiation off the produced hard parton

induced by the dense QCD medium

Parton energy loss µmedium properties:

Flavor dependent energy losses:

Energy is carried away by gluons emittted

inside (broader) jet cone:

“gluonsstrahlung”

Prediction I: Suppression of high pT leading hadrons: dN/dpT

Prediction II: Modification of (di)jet correlations: d2Npair/dφdη

Predition III: Modified energy- & particle- flow within full jet

~collinear but broadened

“Softened” fragmentation

dE/dx ~ s k2T

DEloss(g) > DEloss(q) > DEloss(Q)

(color factor) (mass effect)

SPS,RHIC,LHC

RHIC,LHC

LHC

µ(g density, L)

µ (q coeffic., L2)

GLV:

BDMPS

Wiedemann:

ˆ

Jet physics at RHIC: experimental limits

Full jet reconstruction w/ standard algorithms is unpractical at RHIC due to huge soft background (large “underlying event”):

Feasible at LHC for Ejet >~ 50 GeV

p+p ®jet+jet [Ös = 200 GeV]

Au+Au ® X [ÖsNN = 200 GeV]

“Jet physics” at RHIC (I): Single inclusive high pT spectra

Alternative I : Study the energy modifications suffered by the highest pT hadron in the event (“leading” hadron of the jet) in AA (compared to pp):

Many interesting results obtained from this “first-order” approach !

p+p ® h+ X [Ös = 200 GeV]

Au+Au ® h+X [ÖsNN = 200 GeV]

“Jet physics” at RHIC (II): Di-hadron azimuthal correlations

Alternative II : Study the azimuthal correlations in AA relative to pp between highest pT hadron (“trigger”) & any other “associated” hadron:

Many interesting results obtained from this “2nd-order” approach !

p+p ® h1+h2+ X [Ös = 200 GeV]

Au+Au ® h1+h2+ X [ÖsNN = 200 GeV]

“Jet physics” at RHIC (II): Di-hadron azimuthal correlations

Alternative II : Study the azimuthal correlations in AA relative to pp between highest pT hadron (“trigger”) & any other “associated” hadron:

Many interesting results also obtained from this “2nd-order” approach !

Many interesting results obtained from this “2nd-order” approach !

p+p ® h1+h2+ X [Ös = 200 GeV]

Au+Au ® h1+h2+ X [ÖsNN = 200 GeV]

High pT leading hadron spectra at RHIC
& jet-quenching models:
Good agreement data  theory

Inclusive single spectra at high pT (AA, dA, pp)

High quality large-pT data (up to ~20 GeV/c) available in pp, dA and AA collisions:

Au+Au – 200 GeV

d+Au – 200 GeV

p+p – 200 GeV

Leading hadron spectra in free space: pp @ 200 GeV

High pT p0,h± spectra up to ~15 GeV/c. Good theoret. (NLO pQCD) description

KKP FF

Kretzer FF

(PDF: CTEQ6M)

PHENIX Collab.

PRL 91, 241803

hep-ex/0304038

High quality data: sensitive to different

parametrizations of gluon FF

p+p  p0 X	p+p  h± X

Well calibrated (experimentally & theoret.)

p+p baseline spectra at hand.

Leading hadron spectra in AuAu @ 200 GeV

Au+Au p0 X (peripheral) Au+Au p0 X (central)

Peripheral data agree well with Strong suppression in

p+p (data & pQCD) plus “Ncoll-scaling” central Au+Au collisions !

Suppressed high pT hadroproduction in central AuAu

Discovery of

high pT suppression

(one of most significant

results @ RHIC so far)

D.d'E., HP'04

nucl-ex/0504001

Ncoll scaling

(“hard” production)

x5 suppression

Npart scaling (surface emission)

Very strong suppression (RAA ~ 0.2 !) up to

pT ~ 10 GeV/c for π0 h±, well below incoherent

scattering expectations for hard cross-sections

PHENIX Collab.

PRL 88, 022301 (2002)

nucl-ex/0109003

[Run-2 data]

Hadrons are suppressed. Photons are not.

Colorless hard probes (direct g insensitive to final-state) are unsuppressed.

Confirms that AuAu collision = incoherent sum of pp collisions

(i.e. “Ncoll scaling” expectation is valid) for perturbative probes.

D.d'E, HP'04

EJP C 43 (2005)295

PHENIX.

PRL 94, 232301

Hadrons are suppressed in AuAu. Not in dAu.

Initial-state cold nuclear matter effects (shadowing, Cronin) are small at RHIC mid-rapidity.

High pT suppression in central AuAu is due to final-state effects

(absent in “control” dAu experiment)

D.d'E.,

nucl-ex/0401001

PHENIX.

PRL 91, 072303 (2003)

High pT suppression: “Universal” for all light mesons

Common suppression pattern (magnitude, pT, centrality, ... dependence) for 0 and :

“Jet quenching” model + 1-D longitudinal plasma expansion

The matter is so opaque that even a 20 GeV 0 is stopped.

Same flat RAA ~ 0.2 up to 10 GeV/c

Universal suppression for light mesons indicates it is at partonic level prior to q,g fragmentation into leading meson according to vacuum FFs.

Magnitude of the suppression: medium properties

Data vs. models (pQCD+ non-Abelian parton energy loss) comparison:

Initial gluon densities:

Opacities:

<n> = L/≈ 3 – 4 [Levai et al.]

Transport coefficients:

Medium-induced radiative

energy losses:

dE/dx ≈ 0.25 GeV/fm (expanding)

dE/dx|eff ≈ 14 GeV/fm (static source) [X.N.Wang]

Very large gluon densities: dNg/dy~1000 consistent w/ measured dNch/dη ~700

All medium properties imply energy densities >> ecrit QCD (assuming thermalizat.)

[BDMPS ]

[Salgado-Wiedemann]

[Dainese, Loizides ...]

[Arleo]

dNg/dy ~ 1000 [Vitev & Gyulassy]

<q 0> ~ 14 GeV2/fm

High pT suppression: pT-dependence

Flat pT- dependence described by parton energy loss models:

The matter is so opaque that even a 20 GeV 0 is stopped.

Underlying LPM interference for single gluon bremsstrahlung would give: DEloss ~ log(pT)

Combination of different effects (convolution w/ realistic gluon energy distribution, local parton pT slope, ...) yields constant suppression factor.

PQM

PQM – A. Dainese, C. Loizides, G. Paic

EPJ C 38, 461(2005)

GLV – I. Vitev 2005

High pT suppression: Ös-dependence

Ös- dependence in agreement with parton energy loss in increasingly dense (expanding) medium:

“Jet quenching” model + 1-D longitudinal plasma expansion

D.d'E., HP'04

EJP C 43 (2005)295

RAA ~ 1 @ s ~ 20 GeV Þ dNg/dy ~ 400 , <q0> ~ 3.5 GeV/fm2

RAA ~ 0.3 @ s = 62 GeV Þ dNg/dy ~ 650 , <q0> ~ 7 GeV/fm2

RAA ~ 0.2 @ s = 200 GeV Þ dNg/dy ~ 1100 , <q0> ~ 14 GeV/fm2

[Note: RAA @ SPS

uses “revised” pp ref.]

Initial gluon density:

Medium transport coeff.:

SPS

RHIC

RHIC

High pT meson suppression in AA @ 17.3 GeV ?

Revised pp reference: high pT π0 production in (0-10%) central PbPb at SPS is slighted suppressed or consistent w/ “Ncoll-scaling” :

D.d'E. PLB 596, 32 (2004)

NA57, PLB62, 317 (2005)

Confirmed by NA57 (& NA49) recent high pT results in central PbPb at SPS:

E loss

(Wang)

NA49 (A. Lazslo, QM'05)

High pT suppression: non-Abelian nature

Excitation function (Ös-dependence) & non-Abelian nature of energy loss in agreement w/ parton energy loss calculations:

(i) rising initial parton density with Ös

(ii) increasing relative fraction of hard-scattered gluons (at fixed pT) with Ös

“Jet quenching” model + 2-D longitudinal plasma expansion

D.d'E. EJP C 43 (2005)295

Gluon: CA = Nc = 3

Quark: CF =(Nc2-1)/2Nc = 4/3

Relative fraction of q,g at pT = 5 GeV/c:

QCD radiation probability:

CA /CF=2.25

}

High pT suppression: centrality dependence

Increasing centrality (Npart) Þ increased L, r Þ increased suppression

Agreement data  models as expected for diff. suppressions at different (geometrical) parton production points.

“Jet quenching” model + 2-D longitudinal plasma expansion

PQM – A. Dainese, C. Loizides, G. Paic

EPJ C 38, 461(2005)

X.N. Wang, PLB 2003

High pT leading hadron spectra at RHIC
& jet-quenching models:
Less good agreement data  theory ?

High pT suppression: system-size dependence

Smaller CuCu system adds significant precision at intermediate Npart~100:

Theory predicts: ln(RAA) µNpart-2/3

Both PHENIX & STAR preliminary data seem to exclude = -2/3

Fit to STAR Npart prefers ~ -1/3 (circumf./area ~ A-1/3 ~ Npart-1/3 ?)

PHENIX data seems to indicate a “steeper” slope at low Npart.

Differences STAR  PHENIX and PQM  GLV still unclear at this point.

M. van Leeuwen, QM'05

C.Klein-Boesing, QM'05

High pT suppression: path-length dependence

2 times more suppression out-of-plane (“long” direction)

than in-plane (“short” direction).

Glauber parton energy loss model predicts only ~50% increased “out-of-plane” vs “in-plane” π0 emission

Azimuthal anisotropy stronger than “canonical” L2 (or L) path-length dependence.

Source of extra azim. anisotropy above pT ~ 4 GeV/c ?

 = 0°

 = 90°

PRELIMINARY

[B. Cole, S. Mioduszewski HP'04]

[D.d'E, EJP C 43 (2005) 295]

RAA vs φ w/ respect to reaction plane :

PQM – Dainese, Loizides, Paic EPJ C 38, 461(2005)

Heavy quark suppression via non-photonic electrons (I)

Semi-leptonic decays of open charm and bottom mesons = main source

of high pT (“non-photonic”) electrons.

proton-proton baseline:

Au+Au suppression

(Note: state-of-the-art theory underpredicts data)

Heavy quark suppression via non-photonic electrons (II)

Latest single e± RAA indicates large suppression in central AuAu:

Note: STAR – PHENIX RAA agrees,

but the pp refs are different by ~ 50%.

Peripheral AuAu

Central AuAu

Heavy quark suppression via non-photonic electrons (III)

Theory expectations :

Quantitative predictions:

Models need larger medium densities: dNg/dy=3500, <q> = 14 GeV2/fm than

for light mesons RAA to reproduce data ! Unclear consistency w/ dNch/dy ~ 600

M. Djordjevic et al., nucl-th/0507019

Armesto, Salgado, Wiedemann, QM'05

Charm RAA = 0.2 - 0.3

Beauty RAA = 0.4 - 0.6

DEloss(g) > DEloss(q) > DEloss(Q)

(color factor) (mass effect)

Gluonsstrahlung probability

“Dead cone”: g rad.

suppressed at  < mQ/EQ

Heavy quark suppression via non-photonic electrons (IV)

Models need too dense medium to account for observed suppression in data:

Possible resolutions of the disagreement (or a combination of them ?):

(1) Larger suppression of beauty …or charm dominance up to electron pT ≈ 10 GeV?

(2) Extra gluon-fragmentation production of charm affected by energy loss ? (would also explain PHENIX proton-proton data ?)

(3) Hadronic (+ partonic) energy loss ?

(4) Radiative + collisional energy loss ? Other ... ?

High pT di-hadron φ,η correlations
in high-energy AuAu collisions

“Jet physics” at RHIC (II): di-hadron azimuthal correlations

Study the azimuthal correlations in AA relative to pp between the highest pT hadron (“trigger”) & any other “associated” hadron:

Many interesting results obtained from this “2nd-order” approach !

p+p ® h1+h2+ X [Ös = 200 GeV]

Au+Au ® h1+h2+ X [ÖsNN = 200 GeV]

3-5 GeV/c

d+Au

Near-side

away-side

Dijets via high pT di-hadron φ correlations: pp, dAu

Two-particle correlations: h±- – h±, p0,± – h±. Trigger: highest pT (leading) hadron.

Associated  distribution (e.g. ”assorted”: 2 GeV/c < pTassoc < pTtrigger)

Normalized to number of triggers:

trigger

Phys Rev Lett 90, 082302

STAR Preliminary

Jt = 500 ± 40 ± 150 MeV/c

kt= 1.9 ± 0.2 ± 0.3 GeV/c /<z>

4.5 < Ettrig < 6.5 GeV/c

6.5 < Ettrig < 8.5 GeV/c

ptassoc > 2.0 GeV/c

d+Au (cent, MB)

p+p

2-3 GeV/c

p+p

Preliminary

d+Au

p+p

pTassoc = 2-3 GeV/c

pTassoc = 3-5 GeV/c

Clear near- ( ~ 0) and away- ( ~ p) side jet signals

Dijets via high pT di-hadron φ correlations: AuAu

Same dNpair/dφ analysis as in pp (dAu) but 2 extra “complications”:

(1) Increased “underlying event” background

(2) Collective elliptic flow (harmonic) contribution

Ajitanand, ICPAQGP'04

and nucl-ex/0501025

Delicate subtraction procedure (esp. in finite acceptances).

Di-hadron AuAu Δφ correlations: Results at high pT

Centrality dependence of away-side disappearance globally described by parton energy loss models (increasing medium traversed):

STAR, PRL 90, 082302 (2003)

1/Ntrigger dN/d()

 (radians)

pT trigg = 4 – 6 GeV/c

pT assoc > 2 GeV/c

Away-side peak disappearance:

“monojet”-like topologies

in central AuAu.

Near-side jet-like Gaussian peak

unmodified (AuAu ~ dAu ~ pp)

PQM – A. Dainese, C. Loizides, G. Paic

EPJ C 38, 461(2005)

Di-hadron AuAu Δφ correlations: Results at lower pT

W.Holtzman, RIKEN-Corrs. Workshop '05

“Lost” away-side energy is recovered at lower pT values.

Strongly modified away-side D correlations in central AuAu:

F.Wang, RIKEN-Corrs. Workshop '05

“peak”

“dip”

Std. away-side

Gaussian peak

Preliminary

Away-side () “dip” and excess

of energy (“double peak”) at:

PHENIX: 1.3 rad

STAR: 1.1 rad

Au+Au

periph

Au+Au

central

PHENIX, PRLsubmitted, nucl-ex/0507004

“peaks”

pT trigg = 4 – 6 GeV/c

pT assoc = 0.15 – 4 GeV/c

STAR, PRL95,152301(05)

nucl-ex/0501016

Away-side:

Broadened distribution of

associated low pT hadrons.

pT trigg = 4 – 6 GeV/c

pT assoc = 0.15 – 4 GeV/c

STAR, submitted to PRL

nucl-ex/0501016

“Double peak” = Mach wave cone ?

Double peak structure at at  1.2 rad reminiscent of Mach wave conical shock (“sonic boom”) Þ speed of sound accessible

Note: gluon Cerenkov-like emission also proposed [access to medium index refrac. n=1/cos(c)]

Caveats:

M

Trigger

Calculations based on collisional energy loss alone (does rad. energy

loss fill the cone ?)

(2) The direction of the Mach cone should change w/ the expansion.

Stoecker, Satarov, Mishutin, hep-ph/0505245.
Casalderrey, Shuryak, Teaney, hep-ph/0411315.

Mach cone:

 = arccos(cavs) = 1.2 rad = 71º

c2s ¹ constant:

QGP (1/ Ö3) ® phase transition (0.) ® HRG (Ö0.2) :

~ exp

d+Au, 40-100%

Au+Au, 0-5%

STAR preliminary

3 < pT(trig) < 6 GeV
2 < pT(assoc) < pT(trig)

[D. Magestro, HP'04]

Di-hadron  correlations: AuAu, dAu, pp (I)

Significant broadening of near-side pseudorapidity

correlations in AuAu compared to pp, dAu.

(“stretching” of jet cone along η).

STAR preliminary

p+p

Au+Au, 0-5%

near-side width

d+Au, 40-100%

Au+Au, 0-5%

STAR preliminary

3 < pT(trig) < 6 GeV
2 < pT(assoc) < pT(trig)

Armesto, Salgado, Wiedemann

PRL 93, 242301 (2004)

Di-hadron  correlations: AuAu, dAu, pp (II)

Significant broadening of near-side pseudorapidity

correlations in AuAu compared to pp,dAu.

(“stretching” of jet cone along η).

Coupling of g radiation w/ longitudinal

expanding medium ?

“Cartoon” Summary: Jet-quenching at RHIC

Jet profile in pp (dAu) collisions:

Jet profile in AuAu central collisions:





°





°

Near-side width: <jT> ~ 600 MeV/c

unmodified in pp,dAu

Away-side width and acoplanarity

unmodified in pp and dAu

Factor ~5 suppression of leading hadron

(very large initial parton densities: dNg/dy~1000)

Disappearance of back-to-back peak (“monojets”)

“Double peak” structure at lower pT in away-side

(“sonic boom” in medium ?)

Dijet broadening in η

(coupling of g radiation w/ expanding medium ?)

Strong QCD medium effects at work !

“QCD vacuum” & “cold QCD medium”

“hot & dense QCD Medium”

Summary

Large amount of precision high-pT hadron production data after 5 years of operation at RHIC allows to quantitatively address jet physics in QCD

medium (w/o full jet reco).

Differential observ. of suppressed hadro-production in central Au+Au provide:

- stringent constraints on underlying quenching mechanism.

- direct access to the density & transport properties of QCD medium.

Are “jet quenching” data due to radiative energy loss in a QGP ?

Good agreement with calculations on:

Leading hadrons: Magnitude, √s, pT, centrality, (light) species dependence

Dihadron correlations: disappeareance of away-side azimuthal dijet peak,

Broadening of near-side pseudo-rapidity correlations.

Some tests are weak at present:

Few details missing in system-size dependence

No sharp test of L2 dependence yet.

Heavy quark energy loss larger than expected

New insights of medium properties from new observables (cs via “Mach cone”) ?

LHC = enormous reach, qualitatively new observ. (full jet reco, jet-jet, jet-g,Z ...)

backup slides ...

Di-jet properties: experimental observables

Spread of hadrons around jet axis, relative orientation of the 2 jets: jT, kT, pout

Multiplicity of assoc. hadrons (area under peaks): “fragmentation function” D(z)

hadron

hadron

Jet “width” jT

Di-jet acoplanarity kT

parton

parton

near-side

away-side



[see e.g. J.Jia, nucl-ex/0409024]

D(z), z=p/ptot “Fragmentation function”

“Fragmentation functions”: Central AuAu

syst. error

Near side:

overall

enhancement

from pp to AA

larger initial

parton energy

(and modest

energy loss)?

Away side:

softening of

spectra from pp

to central Au+Au

energy from

initial parton

converted to

low pT particles.

energy loss in

medium!

Associated (pT assoc = 0.15 – 4 GeV/c) near- and away- side hadron pT spectra:

Associated near-side jet yields overall enhanced (enhanced underlying evt.)

Associated away-side jet yields “shifted down” in pT: spectra closer to pure “soft” inclusive hadron production (“thermalized”)

Near-side

Away-side

pT trigg = 4 – 6 GeV/c

pT assoc = 0.15 – 4 GeV/c

STAR, submitted to PRL

nucl-ex/0501016

Jet production in AA : (a few) theoretical expectations

Mono-jets:

Jet broadening in η:

X.N.Wang&M.Gyulassy PRL 68, 1480 (1992)

Armesto et al

hep-ph/0405301

Leading hadron suppression:

Valuable diagnostic tools of QCD medium properties (dNg/dy, <q0>, cs, ...)

Medium-modified FFs:

"Mach cone":

X.N.Wang;

A. Majumder,

Salgado&Wiedem.

Arleo, ...

Bjorken, 1982

dNpair/dφ

dNpair/dη

dN/dpT

M

Trigger

Mach cone:

dN/dzT

Stoecker et al. hep-ph/0505245.
Casalderrey, Shuryak, hep-ph/0411315

nucl-th/0302077

Nchjet increases

<zjet> decreases

Intermediate pT mesons suppressed. Baryons are not

Strongly enhanced baryon (p, L) production at pT ~ 2 – 4 GeV/c

Strong centrality dependent baryon/meson: ratio well above “perturbative” (pp) ratios.

Clear deviation from std. vacuum fragmentation functions (large non-pQCD effects) calls for extra baryon production mechanism: recombination.

Above pT ~ 6 GeV/c: Recovery of “vacuum” fragmentation ratio. Baryons suppressed too.

/K0s

Au+Au 0-5%

p+p

Au+Au 0-10%

p+p

Lamont, QM'05

O.Barannikova, QM'05

Baryon vs. meson “fragmentation functions”

However ... Associated yields similar for meson & baryon triggers.

Magnitude and centrality-dependence of associated (near- & away- side) hadron pT spectra for baryon & meson triggers show small differences.

Jet-like production but different suppression for leading baryons and mesons !?

PRC 71, 051902 (2005)

Near-side

Away-side

pT trigg= 2.5 – 4 GeV/c

pTassoc = 1.7 – 2.5 GeV/c

How to compare high pT spectra in AA and pp ?

High pT particles issue from hard scatterings describable by pQCD:

A

B

AB

dAB → hard = A·B·dpp → hard

dNAB → hard (b) = TAB(b)·dpp → hard

Nuclear Modification Factor:

AB

At impact parameter b:

geom. nuclear overlap at b

production is “shadowed”

TAB ~ # NN collisions (“Ncoll scaling”)

“Factorization theorem”:

Independent scattering of “free” partons:

A+B = “simple superposition of p+p collisions”

High pT suppression: system-size dependence

RAA for Cu+Cu @ √sNN = 200 GeV

Suppression observed for central Cu+Cu

Models scale density from central Au+Au

All models show reasonable to good agreement

STAR preliminary

Charged hadrons

M. van Leeuwen (STAR), QM'05

M. Shimomura (PHENIX), QM'05

PHENIX Preliminary

Di-hadron AuAu: Δφ correlations (III)

Same dNpair/dD result in polar coords. now:

Strongly non-Gaussian

away-side “peak”.

Standard back-to-back

di-jet topology.

Au+Au peripheral

Au+Au central

PHENIX Collab. PRL to be submitted

Jet production in the “QCD vacuum” (pp collisions)

Jet : Collimated spray of hadrons in a cone ( ~ 0.7) with 4-momentum of original fragmenting parton

Leading hadron takes away large fraction (<z> ~0.6 –0.8 @ RHIC) of parent parton pT

Jet balanced back-to-back by other hard-scattered "parton" (jet, direct g, ...) A (small) acoplanarity appears due to intrinsic kT (parton Fermi motion).

Jet production in “QCD media” (pA, AA collisions)

kT broadening

(Cronin enhancement)

(Leading-twist) shadowing

or gluon saturation (CGC)

Final-state effects

Parton energy loss due to medium-induced

gluon-strahlung in hot & dense environment

Initial-state effects

(accessible via pA colls.):

(accessible in AA colls.):

“Fragmentation functions”: xE distributions pp,dAu

 Dq(z)~e-6z

independent of pTt

<ztrig>=0.85 measured*

Away-side associated hadron pT spectra:

xE ~ z/<ztrig> represents away jet fragmentation z

xE variable: Two-particle equivalent of fragmentation variable z

At high pT, i.e. when di-jets are nearly back-to-back.

David d'Enterria

2004-01-14T06:23:12