Kenji Morita

HHIQCD2015@YITP

L-L Interaction fromRelativistic Heavy Ion Collisions
Kenji Morita(YITP, Kyoto)in Collaboration withAkira Ohnishi (YITP)
Takenori Furumoto (Ichinoseki National Col.)Ref.) Phys. Rev. C91, 024916 (2015)2014 March 41

Kenji Morita (YITP, Kyoto)

OutlineGoal : LL interaction from HIC
1. Introduction
2. Effect of LL interaction (w/ simplest source)
3. +Collective Expansion
1. Spherical source
2. Bjorken and transverse expansion

4. Feed-down Contribution
5. Residual Correlation
6. Summary2014 March 4

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Role of LL Interaction
Possible Emergence of Hyperons in NS core
To understand EoS,
Information on
Hyperon-Hyperon
Interaction isindispensablefrom KEK.jp

H-dibaryon (uuddss)?
L-L bound state due to strong attraction?
Resonance?
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Kenji Morita (YITP, Kyoto)

RHIC Can Tell Us about LL interaction
Au+Au 200AGeV
×108 events(60-80%) (0-5%)
pp

p

N

p1

Np
LNpp

Np
NLpp
Hadronizationp2~5 fm/c, ~160MeV2014 March 4N

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Kenji Morita (YITP, Kyoto)

LL Correlation in HIC
Independent (Chaotic) emission(←Thermal Source)L

Identical particle correlation fromquantum statistics (HBT effect)

R

C(Q) : effective source size
L

LL Interaction : No Coulomb!

1

Affects C(Q) when effective range
reff is comparable with R
Different results for repulsive andattractive interaction

0.5
C(Q)

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Kenji Morita (YITP, Kyoto)

Approach : Thermal Source + VLL
Formula (Gong et al., ‘91)

LL relative S-wave func.

Emission source func.
Thermal source model(Mimic hydro)

Various potentials (via 2 or 3 rangeGaussian Fit)

 Static Spherically Symmetric

Meson exchange models (Nijmegenmodel D, F, Soft Core89/97, ESC08)

 Spherically Symmetric + Hubble Flow Cylindrically Symmetric + Boostinvariance + Transverse flow
2014 March 4

Phenomenological (Ehime)
Quark model (fss2)
Fit to LL6He(Nagara) Filikhin-Gal (FG)
Hiyama et al. (HKMYY)

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Kenji Morita (YITP, Kyoto)

Potential, Wave func., / Correlation
Correlation Function for the Static SourceS-wave w.f.

HBT (size R)

Interaction : deviation from free w.f.

Input VLL

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Kenji Morita (YITP, Kyoto)

Expanding Source Model

S.Chapman et al., ‘95

Give a finite longitudinal extent
Width of C(Q) (Q=|p1-p2|) :effective 3d size

Large RL : narrow width

Transverse flow: fit to pt
distribution of L (STAR ’12)2014 March 4

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Kenji Morita (YITP, Kyoto)

Illustration : Spherical Source

Expansion makes the apparent source size smaller
Attraction in C(Q) becomes stronger
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Kenji Morita (YITP, Kyoto)

Results from Boost-invariant Source

Effect of hf is rather small : longitudinal expansion dominates C(Q)

Behavior at small Q is different from the static source !
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Kenji Morita (YITP, Kyoto)

Combined effects from flow and VLL(min. c2 against R)

Effect of hf is absorbed into change of RoptLongitudinal expansion gives another type of “best fit”
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Kenji Morita (YITP, Kyoto)

VLL from Expanding Source Model
Same VLL are chosen withsmaller R!

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Kenji Morita (YITP, Kyoto)

Feed-Down Contribution
Assume X is not included
DCA < 0.4cm from the primary vertex

S0 → L + gL

R≫1/Q
L(0.67)2
consistent w/ thermal model

Using S0/L =0.278 (p+Be data) and X/L = 0.85 (RHIC), Ldir/Ltot = 0.67
(0.52 if including X)
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Kenji Morita (YITP, Kyoto)

Feed-Down EffectSensitivity at low Q is reduced

Free C(0)Unphysically small size is preferred;
due to the long tail in C(Q) which cannot be
included in the present framework
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Kenji Morita (YITP, Kyoto)

Long Tail : Residual Correlation?
Assuming a short-range
correlation
Search for min c2 in(ares, rres) for each R
c2/Ndof ~ 1 for shown Rrange
Small R : Large rres > R
Low Q behavior
2014 March 4

X

LL Interaction
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Kenji Morita (YITP, Kyoto)

An Example for Agreement

Smaller difference than error-bars
FG and fss2 have the almost same a0

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Kenji Morita (YITP, Kyoto)Constraints on a0 and reff
1/a0 < -0.8 [fm-1]
No constraint on reff

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Kenji Morita (YITP, Kyoto)

Summary and Outlook
RHIC has potential to determine LL interaction
Expansion effect modifies low Q behavior
Ideal measurements (i.e., decay contribution issubtracted) will give strong constraints
Feed-down effect reduces resolving power
Long-tail in STAR data needs to be subtracted
and its origin needs to be understoodScattering length 1/a0 < -0.8 fm-1

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Kenji Morita (YITP, Kyoto)

Backup2014 March 4

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Kenji Morita (YITP, Kyoto)

Analysis by STAR Coll.

arXiv:1408.4360

Fit w/ Lednicky-Lyuboshitz model
Data: long tail (→ Small source size)
Introduce “residual correlation” fora better fit to data

HBT (size r0)
1.006
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Interaction

2.96 fm
HHIQCD2015@YITPResidual correlation-0.0440.43 fm
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Kenji Morita (YITP, Kyoto)2014 March 4

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Kenji Morita (YITP, Kyoto)

Results from the Static Source

Strong attraction
is reflected ontoC(Q)Larger variation among potentials than data error-bars
Size : determined from min. c2
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Collectivity Deforms Source Function

Influence on the best-fit potentials?

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C(Q) is fairly sensitiveto interaction

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Kenji Morita (YITP, Kyoto)

Scattering Length and Effective Range-1.8 < 1/a0 < -0.8 [fm-1]
3.5 < reff < 7 [fm]S0 feed-down affects this ?

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