femtoscopy at the highest energies: expectations and directions at the lhc

malisa - SPHIC - Catania Italy - Sept 2006 1

Femtoscopy at the highest energies:Expectations and directions at the LHC

Mike Lisa

Ohio State University


Outline• Femtoscopic expectations @ LHC

• NNUS: systematic extrapolation of existing systematics• naïve• CGC

• cascade• HRM: microscopic hadronic rescattering model• AMPT: HIJING+parton cascade+string frag+hadronic cascade

• hydro• scales• shapes

• p+p• Pythia (+HRM, jets)• Black holes

• Some directions at LHC

• Summary


Femtoscopic information

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C r P

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Sr P

ab( ′ r r ) =

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φ(r ′ q ,r ′ r ) = (a,b) relative wavefctn

know/assume source distrib extract interaction (scat. length..)

know/assume relative wavefunction extract spatial distributions

OR


Microexplosions Femtoexplosions

s 0.1 J 1 J

1017 J/m3 5 GeV/fm3 = 1036 J/m3

T 106 K 200 MeV = 1012 K

rate 1018 K/sec 1035 K/s

• energy quickly deposited• enter plasma phase• expand hydrodynamically• cool back to original phase• do geometric “postmortem” & infer momentum


Baseline: 20-year-old systematic program

• Pion HBT @ Bevalac: “largely confirming nuclear dimensions”• Since 90’s: increasingly detailed understanding and study w/ high stats

T 1 2 sysˆHBT( ;p , y, b ,b,ms ,m ,A )

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1985 1990 1995 2000 2005 2010

Year

#

Heinz/JacakWiedemann/Heinz

Csorgo

Tomasik/Wiedemann

Lisa/Pratt/Solts/Wiedemann

Experimental HBT Refereed Journal Publications


R(√SNN, b, Npart, A, B, y, mT, , PID)

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R i mT( ) =′ R i

mTα i

fast region

fast region


R(√SNN, b, Npart, A, B, mT, y, , PID)

PRL 87 082301 (2001)PRL 93 012301 (2004)PRC 71 044906 (2005)

PRC 71 044906 (2005)

PRL 93 012301 ‘04

Spectra

v2

HBT


€

R i mT( ) =′ R i

mTα i


Z. Chajecki, QM05



PRL 87 082301 (2001)PRL 93 012301 (2004)PRC 71 044906 (2005)

PRC 71 044906 (2005)

PRL 93 012301 ‘04

D. Flierl, PhD thesis 2002

Spectra

v2

HBT

PRL 91 262301 (2003)

emission region

K emission region



PRL 87 082301 (2001)PRL 93 012301 (2004)PRC 71 044906 (2005)

PRC 71 044906 (2005)

PRL 93 012301 ‘04

D. Flierl, PhD thesis 2002

Spectra

v2

HBT

PRL 91 262301 (2003)

emission region

K emission region

STAR, PRL 2004

MAL,Pratt Soltz,Wiedemann nucl-ex/0505014

+ - K+ K- K0S p p

p

p

K0S

K-

K+

-

+

Full program just startedEvolution with energy?


€

R i mT( ) =′ R i

mTα i


Z. Chajecki, QM05

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

MAL, Pratt, Soltz, Wiedemann nucl-ex/0505014 STAR, PRL 2004


€

R i mT( ) =′ R i

mTα i


Z. Chajecki, QM05





Naïve (?) : multiplicity dominance continues @ LHC(though two unexplored areas...)

Little dataShape Evolution with energy?


Source imaging - inverting Koonin-Pratt equation

•Non-Gaussian source in 1D (long-known)

•imaging resolves long-range component

•STAR sees similar (see talk of M. Bysterský

•Resonances? [check size scaling]

PHENIX nucl-ex/0605032

€

C r P

ab(r q ) = d3 ′

r r ⋅Sr

P

ab( ′ r r )∫ ⋅ φ(

r ′ q ,r ′ r )

2

€

Sr P

ab( ′ r r ) =

r x a -

r x b( ) distribution

φ(r ′ q ,r ′ r ) = (a,b) relative wavefctn


€

R i mT( ) =′ R i

mTα i


Z. Chajecki, QM05





Naïve (?) : multiplicity dominance continues @ LHC(though two unexplored areas...)

Little dataShape Evolution with energy?

malisa - SPHIC - Catania Italy - Sept 2006 16PHOBOS White Paper: NPA 757, 28

1000 5.5 TeV

5

6

6.4 = RHICx1.6


Multiplicity sets scale: all else fixed


PHOBOS White Paper: NPA 757, 28

1000 5.5 TeV

5

6

6.4 = RHICx1.6



• PHOBOS-based extrapolation:• RLHC / RRHIC = (1.6)1/3 = 1.17

PHOBOS White Paper: NPA 757, 28

1000 5.5 TeV

5

6

6.4 = RHICx1.6




• CGC prediction of multiplicity

• RLHC / RRHIC = (11/3.6)1/3 = 31/3 = 1.45

Kharzeev, Levin & Nardi NPA747 609 (2005)


Beyond multiplicity



• RLHC / RRHIC = (11/3.6)1/3 = 31/3 = 1.45

• Humanic Rescattering Model

• “real” model predicting dN/d and HBT

• (dN/d[LHC] / dN/d[RHIC])1/3 ~ 1.9

dN

/d

T. Humanic,Int.J.Mod.Phys.E15197(2006)


Beyond multiplicity

Rlo

ng (

fm)

dN

/dt



• RLHC / RRHIC = (11/3.6)1/3 = 31/3 = 1.45



• (dN/d[LHC] / dN/d[RHIC])1/3 ~ 1.9

• LHC / RHIC = 2 :: (recall Rlong~~ )

• dynamic effect

• Rlong[LHC] / Rlong[RHIC] ~ 1.5-2

• all are connected??



Beyond multiplicity



• RLHC / RRHIC = (11/3.6)1/3 = 31/3 = 1.45



• (dN/d[LHC] / dN/d[RHIC])1/3 ~ 1.9


• dynamic effect

• Rlong[LHC] / Rlong[RHIC] ~ 2

• all are connected?

• RS, RO larger, but not a simple factor



Beyond multiplicity



• RLHC / RRHIC = (11/3.6)1/3 = 31/3 = 1.45



• (dN/d[LHC] / dN/d[RHIC])1/3 ~ 1.9


• dynamic effect

• Rlong[LHC] / Rlong[RHIC] ~ 2

• all are connected?

• RS, RO larger, but not a simple factor

• steeper pT-dep due to more flow?

• dynamic effect



hydro

• does not do as well as

cascades, but nevertheless

we’ll look next for guidance...

Cascade / Hydro models versus RHIC data

cascade

• AMPT does ~Ok- needs string melting

& 6-10 mb parton


AMPT @ LHC

• All radii increase• ~10% for transverse• ~30% for long

• RO/RS [LHC] < RO/RS [RHIC]

• But... RHIC radii too large in this configuration of model ???

C.M. Ko; WPCF Sept. 2006


Hydro predictions I: Scales

• Neglecting flow, to cool to C[QGP] :

C = 0(C /0)3/4

• Cno flow[RHIC] = 6 fm/c

• Cno flow[LHC] = 20 fm/c

Eskola et al PRC72044904 (2005)

initial conditions frompQCD+saturation



C = 0(C /0)3/4



• Much larger flow @LHC• signif. reduction of timescale @ LHC

[similar to RHIC]

• larger transverse size @ FO





C = 0(C /0)3/4




[similar to RHIC]


• No HBT prediction per se, but...

• RL[LHC] / RL[RHIC] ~ 1.1 ÷ 1.2

• RS[LHC] / RS[RHIC] ~ 1.5 ÷ 2

• (different than HRM)

• steeper pT-dependence





C = 0(C /0)3/4




[similar to RHIC]


• No HBT prediction per se, but...

• RL[LHC] / RL[RHIC] ~ 1.1 ÷ 1.2

• RS[LHC] / RS[RHIC] ~ 1.5 ÷ 2

• (different than HRM)

• steeper pT-dependence

• Consistent w/ independent hydrofor non-central collisions



Heinz&Kolb, PLB542 216 (2002)

(LHC)


• easy prediction: importance of -dep measurements will continue @ LHC

• asHBT• probes timescale & dynamics• non-trivial (& incomplete!) excitation fctn

Hydro predictions II: Shapes

E895 2 GeVPLB496 1 (2000)

STAR 200 GeV

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• hydro @ RHIC• misses scale (well-known)• impressive agreement on -dep


STAR PRL93 012301 (2004)Heinz&Kolb, PLB542 216 (2002)

“RHIC”





• prediction @ LHC• sign change in shape & oscillations



“RHIC”


“IPES” (LHC)





• prediction @ LHC• sign change in shape & oscillations

• qualitatively different kT dependence (*)



“RHIC”


“IPES” (LHC)

* simple formula will not work @ LHC

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≈2RS,2

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p+p: a short diversion and “practice,” or a crucial question?

• “minimalist” physics• Momenta & parentage from PYTHIA• space by hand: x= “1 fm” + p/E

• pT-dep from x-p correlations

• resonances• formation time • some from rescatt

• mult dep from rescatt only

i-th particle

Initial “disk” of radius r

T. Humanic, presentationto ALICE PW2 (March 2006)







• R(dN/d) space-time properties of jet fragmentation/hadronization? [fundamental]

• prediction of pT-dependence needed to test

whether hard processes are really dominant here

pp

jet

jet

Paic and SkowronskiJ. Phys. G31 1045 (2005)

see also Csorgo & Zajchep-ph/0412243 (ISMD04)







• R(dN/d) space-time properties of jet fragmentation/hadronization? [fundamental]

• prediction of pT-dependence needed to test

whether hard processes are really dominant here

• Black Holes / extra dimensions at LHC p+p ?• may be copiously produced (depending on mass)• look for long lifetimes (if d large) in high mult

events ???• even more fundamental, but expectations unclear

[prelim from T. Humanic: small effect on HBT...]

Hossenfelder, H

ofmann, B

leicher, Stocker

Phys.R

ev. D66 (2002) 101502

Humanic, Koch, Stocker hep-ph/0607097


STAR preliminary

mT (GeV) mT (GeV)

Z. Chajecki WPCF05

femtoscopy in p+p @ STAR

• p+p and A+A measured in same experiment

• great opportunity to compare physics

• what causes pT-dependence in p+p?

• same cause as in A+A?


Surprising („puzzling”) scaling

HBT radii scale with pp

Scary coincidence or something deeper?

pp, dAu, CuCu - STAR preliminary

Ratio of (AuAu, CuCu, dAu) HBT radii by pp

• p+p and A+A measured in same experiment

• great opportunity to compare physics

• what causes pT-dependence in p+p?

• same cause as in A+A?

!! But !! major issues with nontrivialinterplay non-femtoscopic correlations


5

as before (same pT dep etc)but scale by ~17%

as before (same pT dep etc)but scale by ~45%

NNUS: naive extrapolation HRM and AMPT

RL (50-100% 30%increase)[dynamics / chemistry / both ??]

RO,S • smaller increase (~30% 10%)• higher flow steeper pT dep

hydro

RL small increase (~30%)[huge flow rapid cooling short ]

RO,S : huge flow • larger increase (~60%)• steeper pT dep

shape inversion; oscillation sign flip

p+p

pp

jet

jet

• signif pT dep• R increase w/ mult

• R increase w/ mult• other details??

• very large RO in high mult??

plats principaux

boissonsentrées

le menu des espérances au LHC


“Inverting the femtoscopic paradigm”

• First-ever p-, p-, p- correlations

• Consistency from baryon sector for flow-generated x-p correlations

• Extraction of real/imaginary p-, p- scattering lengths from CF !!• important new physics direction• “invert the femtoscopic paradigm”• c.f. K0-K0 / p-p

• possible effect of residual correlations - could not reliably calculate (for now...)• significant technical effort (and

more information) required

STAR, accepted to Phys Rev


• p+p - very interesting in itself!• understanding non-femtoscopic correlations crucial

• Beyond Gaussian imaging (3D)• see M. Bystersky

• shape inversion?• correlate femtoscopy with global event plane

• non-id systematics• including “exotica”

• will seriously need to understand correlated feed-down• see talk of H. Gos• a “complication” and a new source of information !

• hadronic physics - extracing phaseshifts• turning the problem around

nouvelles directions


THE END


references• RHIC-tested predictions for low-pT and high-pT hadron spectra

in nearly central Pb+Pb collisions at the LHC• Eskola et al hep-ph/0506049; PRC72044904 (2005)• hydro predictions for spectra• no HBT per se, but timescales and sizes of freezeout at

LHC versus RHIC are shown• Emission angle dependent pion interferometry at RHIC and

beyond• Heinz and Kolb PLB542 216 (2002)• RHIC and LHC predictions for asHBT from hydro

• Signatures for Black Hole production from hadronic observables at the Large Hadron Collider

• Humanic, Koch, Stocker hep-ph/0607097• surprisingly, no HBT, but discussion of possible BH

formation, rates, and how to trigger on them (high-mult: will it follow multiplicity systematics if physics changes so much??)

• Femtoscopy in heavy ion collisions: Wherefore, whence, and whither?

• Lisa nucl-ex/0506049 (WPCF05)• systematics and PHOBOS-extrapolation-based “prediction”

for LHC• Color Glass Condensate at the LHC: hadron multiplicities in pp,

pA and AA collisions• Kharzeev, Levin & Nardi; NPA747 609 (2005)• not HBT, but multiplicity predictions, which of course can

be coupled to HBT multiplicity systematics

• Hanbury-Brown-Twiss interferometry with identical bosons in relativistic heavy ion collisions: Comparisons with hadronic scattering models

• Humanic, Int.J.Mod.Phys.E15:197-236,2006; nucl-th/0510049

• Tom’s review article; contains LHC predictions

For proton-proton collisions:• Signatures for Black Hole production from hadronic

observables at the Large Hadron Collider• Humanic, Koch, Stocker hep-ph/0607097• surprisingly, no HBT, but discussion of possible BH

formation, rates, and how to trigger on them (high-mult: will it follow multiplicity systematics if physics changes so much??)

• Quasi-stable black holes at LHC• Hossenfieder, Hoffman, Bleicher, Stocker

hep-ph/0109085; Phys.Rev. D66 (2002) 101502• VERY nice plot of lifetime versus number of dimensions

• Pion HBT for LHC p+p collisions using a simple causality model

• Humanic, ppt presentation at PW2 meeting March 06• Pythia and HRM - nice, simple calculations showing pT

dep from simple formation time effect• Effect of hard processes on momentum correlations in pp

and ppbar collisions• Paic and Skowronski; J. Phys. G31 1045 (2005)• from size and mult dep, make a connection to space-

time properties of jet fragmentation• unfortunately, no pT prediction


Why can’t HBT be

more like v2?


STAR preliminary

v2 excitation functionpT-integrated

NA49: Phys.Rev. C68 (2003) 034903

slide of Raimond Snellings HIF 2003

Why can’t HBT be more like v2...?


Why can’t HBT be more like v2...?• v2(pT) very similar

• <pt> 158 A GeV ≈ 400 MeV/c

• <pt> 200 GeV ≈ 500 MeV/c

• Integrated v2 mainly driven by <pt>

• Note: In comparison SPS data the slight difference in centrality and systematic uncertainties, about 1.5% are

not plotted

STAR Preliminary

NA49: Phys.Rev. C68 (2003) 034903; CERES: nucl-ex/0303014

slide of Raimond Snellings HIF 2003

v2(pt) SPS-RHIC


Why can’t HBT be more like v2...?It can!.....Just gotta look in less detail!

femtoscopy at the highest energies: expectations and directions at the lhc

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