The Strange Baryon-Baryon Interaction J urgen Schaffner-Bielich - - PowerPoint PPT Presentation

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

The Strange Baryon-Baryon Interaction

J¨ urgen Schaffner-Bielich

Institut f¨ ur Theoretische Physik

Chiral Group Meeting Frankfurt, June 6, 2016

HGS-HIRe

Helmholtz Graduate School for Hadron and Ion Research

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Content

1

Hyperon-Nucleon Interaction: Hypernuclei

2

Baryon-Baryon Interactions: Dibaryons

3

Finding Strange Matter

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Content

1

Hyperon-Nucleon Interaction: Hypernuclei

2

Baryon-Baryon Interactions: Dibaryons

3

Finding Strange Matter

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Baryon octet and decuplet

eightfold way: baryons have three quarks lowest multiplets: octet (spin 1/2) and decuplet (spin 3/2) baryon mass increases with number of strange quarks (strangeness) nucleon (no s-quark): mN = 940 MeV → nuclear chart

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Baryon masses

hyperons with one s-quark: mΛ = 1116 MeV, mΣ+ = 1189 MeV, mΣ0 = 1193 MeV, mΣ− = 1197 MeV hyperons with two s-quarks: mΞ0 = 1314 MeV, mΞ− = 1321 MeV hyperon with three s-quarks: mΩ− = 1672 MeV (spin 3/2, Pauli principle!) bound system with nucleons and hyperons: hypernuclei!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

First hypernuclear event

first hypernuclear measurement: 1953 by Danysz and Pniewski from cosmic ray emulsion event unique double-star feature

• n emulsion plate: one

from hypernuclear production, one from hypernuclear decay!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Danysz and Pniewski

Polish postcard commemorating Danysz and Pniewski (check out the stamp!)

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Hypernuclear production mechanism

hypernuclei produced by incoming K − beam nucleon transformed to a hyperon: K − + n → Λ + π− measurement by outgoing π− prominent feature: recoilless production, Λ is produced at rest inside nucleus!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Light hypernuclei

• 4
• 6
• 8
• 10
• 12
• 14

Exp. RMF 6 8 10 12 14 16

AtomicMassA BindingEnergy(MeV) LightHypernuclei(Restrictedfit)

emulsion data up to mass number A = 15 good measurement of Λ binding energies increases linearly with mass number

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Hypernuclear spectra and levels

peak structure in pion spectra related to single-particle levels of hypernucleus! first surprise: tiny spin-orbit splitting for 16

ΛO

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Nuclear and hypernuclear levels in 17

Λ O

hyperon potential (dotted) is shallower than nucleon potential (solid line) Coulomb potential: dot-dashed line spin-orbit splitting for hyperons is much smaller than for nucleons

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Heavy hypernucleus 89

ΛY

(Hotchi et al., PRC 61 (2001) 044302)

modern spectroscopy of hypernuclei via reaction: π+ + n → Λ + K + several hypernuclei measured up to 208

ΛPb, measured

shells: s, p, d, f, g and h!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Λ Single–Particle Energies

0.05 0.1 0.15 0.2 0.25

10 20 30 Binding Energy (MeV)

(pi,K) (e,e’K) Emulsion (K,pi)

Λ Single Particle States

A−2/3

sΛ pΛ dΛ fΛ gΛ

208 139 89 51 4032 28 16 131211 10 8 7 (Gal, Hungerford, Millener 2016)

measured with pion, kaon or electron beams or in emulsion spin–orbit splitting smaller than experimental resolution fit to single particle energies: UΛ = −27 MeV for A → ∞ note: only for the Λ (besides nuclei) do we know its in-medium properties!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Hypernuclear chart (Bando 1990)

many light hypernuclei observed in emulsion experiments (up to A=15) heavier systems measured spectroscopically

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

HypHI program at GSI (Take Saito et al.)

exploration of the whole hypernuclear chart for light systems! determination of the hypernuclear drip-line note: hyperons stabilize nuclei, 8Be is unbound, but 9

ΛBe is bound!

evidence for 6

ΛH by the FINUDA collaboration (2012)!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Hyperon decays

Hyperons decay mainly by weak interactions: conserves baryon number and charge but changes strangeness by one unit Λ → p + π−(64%), n + π0(36%) Σ+ → p + π0(52%), n + π+(48%) Σ0 → Λ + γ (electromagnetic) Σ− → n + π− Ξ0 → Λ + π0 Ξ− → Λ + π− typical lifetime: τ ≈ 10−10 seconds

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Hypernuclear decays

(Park et al., PRC61 (2000) 054004)

Hyperons in the medium can also decay non-mesonically: Λ + N → N + N, Σ + N → N + N Ξ + N → Σ + N or Λ + N, Λ + Λ → Σ + N or Λ + N . . . nonmesonic decay dominates already for moderate mass number! hypernuclear lifetime saturates around 200 ps

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Sigma-atomic states

Σ− bound mainly by Coulomb forces to a nucleus slight shift of energy levels due to strong interactions Σ-potential is attractive at low densities but repulsive inside the nucleus → no bound Σ-hypernuclear states (Mares, Friedmann, Gal, Jennings 1995)

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Sigma hypernuclei

(Bart et al., PRL 83 (1999) 5238)

• lder data: peaks in Σ-hypernuclear spectra, bound states?

recent data: no peaks, strongly repulsive Σ-potential needed to explain spectrum!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Sigma hypernuclear potential

(Harada and Hirabayashi 2005)

indirect measurement of Σ-nucleon potential by (π−, K +) reaction on 28Si: UΣ ≈ +30 MeV depends also on imaginary part

• f the potential (absorption)

combining with Σ-atomic data: need density dependent potential (attractive at low densities, repulsive in the nuclear core)

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Xi hypernuclei (Dover and Gal 1983)

Hypernucleus BΞ− [MeV] BΞ0 [MeV]

8 ΞHe

8.1∗ ± 1.2 14.2 ± 1.8

11 Ξ B

9.2 ± 2.2 0.4 ± 2.8

13 Ξ C

18.1 ± 3.2 −4.3 ± 3.8

15 Ξ C

16.0 ± 4.7 11.1 ± 5.3

17 Ξ O

16.0 ± 5.5 −4.5 ± 6.1

28 Ξ Al

23.2 ± 6.8 13.3 ± 7.4

first bound Ξ hypernucleus seen in 1959 (Wilkinson, Lorant, Robinson, Lokanathan, PRL 3 (1959) 397) incoming pion beam produces first star two short tracks towards south and north: two hypernuclei emitted! interpretation: 8

ΞB with BΞ = 8.1 ± 1.2

(corrected for modern value of mΞ) Ξ reacts via Ξ + N → Λ + Λ to form two hypernuclei

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Xi hypernuclear potential

double strangeness exchange reaction: (K −, K +) deposits two units of strangeness into the nucleus! indirect measurement of Ξ-nucleon potential by (K −, K +) reaction on

12C: UΞ ≈ −14 MeV

(Khaustov et al. (E885 collaboration) 2000) relativistic potential: UΞ ≈ −18 MeV

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Xi-14N Hypernucleus Event

(Nakazawa et al. 2015)

E373 experiment at KEK production process: Ξ−+14N→10

ΛBe+5 ΛHe

binding energy of BΞ− = 4.38 ± 0.25 MeV

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

ΛΛ Hypernuclei

1963 Danysz et al.:

10 ΛΛBe→9 ΛBe+p + π−, △BΛΛ = 4.3 ± 0.4 MeV

1966 Prowse:

6 ΛΛHe→5 ΛHe+p + π−, △BΛΛ = 4.7 ± 0.6 MeV

1991 E176 (KEK):

13 ΛΛB→13 ΛC+π−, △BΛΛ = 4.8 ± 0.7 MeV

(Dover, Millener, Gal, Davis 1991) 2001 E373 (KEK):

6 ΛΛHe→5 ΛHe+p + π−, △BΛΛ = 1.0 ± 0.2 MeV!

2001 E906 (BNL):

4 ΛΛH→4 ΛHe+π− or 7 ΛΛLi (Randeniya and Hungerford 2007)

ΛΛ interaction is weakly attractive total binding energy of two Λ’s: BΛΛ(A

ΛΛZ) = BΛ(A ΛΛZ) + BΛ(A−1 Λ

Z) additional bond energy: △BΛΛ(A

ΛΛZ) = BΛ(A ΛΛZ) − 2BΛ(A−1 Λ

Z)

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Updated world data on ΛΛ hypernuclei (2011)

(Gal and Millener 2011)

three modern events, comparison to shell model and cluster model calculations

• nly uniquely identified double Λ hypernucleus:

6 ΛΛHe !

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Summary of Hypernuclear Systems

NΛ: attractive → Λ-hypernuclei for A = 3 − 209 UΛ = −30 MeV at n = n0 NΣ: 4

ΣHe hypernucleus bound by isospin forces

Σ− atoms: potential is repulsive NΞ: attractive → 7 Ξ hypernuclear events UΞ = −28 MeV at n = n0 quasi-free production of Ξ: UΞ = −18 MeV ΛΛ: attractive → 5 ΛΛ hypernuclear measurements YY: Y= Λ, Σ, Ξ, unknown! hypernuclear programs at: DaΦne, JLab, J-PARC, MAMI, and PANDA, HYPHI @FAIR!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

PANDA at GSI: Measurement of double Λ hypernuclei

production of Ξ via antiproton beam on nuclei capture of Ξ in another nucleus γ-spectroscopy of produced double-Λ hypernucleus

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Content

1

Hyperon-Nucleon Interaction: Hypernuclei

2

Baryon-Baryon Interactions: Dibaryons

3

Finding Strange Matter

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Multi-Quark States: Some History (incomplete)

multi-quark states already mentioned by Gell-Mann in 1964 strange four-quark states (qs¯ q¯ s): Jaffe 1977 strange six-quark states (qqqqss: H-dibaryon): Jaffe 1978 heavy tetraquarks (QQ¯ q¯ q): Ader, Richard, Taxil 1982 pentaquarks with charm (qqqs¯ c): Lipkin 1987 and Gignoux, Silvestre-Brac, Richard 1987 . . . light pentaquark (qqqq¯ s) in chiral soliton model: Diakonov, Petrov, Polyakov 1997 light pentaquark in diquark model: Jaffe and Wilczek 2003

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Classification of Strange Dibaryons

−S\Z

• 2
• 1

+1 +2 nn np pp 1 Σ−n Λ n Λ p Σ+p 2 Σ−Σ− Ξ−n ΛΛ Ξ0p Σ+Σ+ 3 Ξ−Σ− Ξ−Λ Ξ0Λ Ξ0Σ+ 4 Ξ−Ξ− Ξ0Ξ− Ξ0Ξ0 5 Ξ−Ω− Ξ0Ω− 6 Ω−Ω−

(JS, C.Greiner, St¨

• cker 1992, JSB, Dover, Gal, Millener, C.Greiner, St¨
• cker 1993, 1994)
• rdering according to lowest sum of vacuum masses for given

strangeness S and charge Z

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Hyperon-Nucleon scattering data

50 100 150 200 250 100 200 300 400 500 600 700 800 900 σ [mb] pLab [MeV/c] Λp -> Λp ESC08c Eff.range I Eff.range II 50 100 150 200 140 150 160 170 180 σ [mb] pLab [MeV/c] Σ+p -> Σ+p #-sections ESC08c ESC04d NSC89 50 100 400 500 600 700 pLab [MeV/c] Σ+p -> Σ+p #-sections 50 100 150 200 250 300 140 150 160 170 σ [mb] pLab [MeV/c] Σ-p -> Σ-p #-sections ESC08c ESC04d NSC89p 50 100 400 500 600 700 pLab [MeV/c] Σ-p -> Σ-p #-sections 50 100 150 200 140 150 160 170 180 σ [mb] pLab [MeV/c] Σ+p -> Σ+p #-sections ESC08c ESC04d NSC89 50 100 400 500 600 700 pLab [MeV/c] Σ+p -> Σ+p #-sections 50 100 150 200 250 300 140 150 160 170 σ [mb] pLab [MeV/c] Σ-p -> Σ-p #-sections ESC08c ESC04d NSC89p 50 100 400 500 600 700 pLab [MeV/c] Σ-p -> Σ-p #-sections

(Nagels, Rijken, Yamamoto 2015)

total Λp cross sections (left), elastic Σ±p cross section (middle), inelastic Σ±p cross section (right) model fits for different Nijmegen models (NSC: Nijmegen soft core, ESC: Extended soft core) ingredients: one boson exchange of meson nonets, pomeron and odderon exchange, two pseudoscalar exchange, meson pair exchange

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Baryon-baryon potentials: SU(3) symmetry

(Stoks and Rijken 1999)

classify states according to SU(3) coupling of two octets: 8 × 8 = 1 + 8 + 8 + 10 + 10∗ + 27 NN has bound state in 3S1 −3 D1 (deuteron) → {10∗} NN has quasi-bound state in 1S0 (E = +90 keV) → {27} SU(3) symmetry: bound states in all pure {10∗} broken SU(3): quasi-bound states become bound as hyperons are heavier than nucleons

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Baryon-baryon potentials: Nijmegen soft-core models

Nijmegen soft core model NSC97a-f (newer versions of extended soft-core model: ESC04-08)

• ne-boson exchange model for pseudoscalar, scalar, and

vector mesons uses SU(3) flavour symmetry fitted to NN and NY scattering data predictions for dibaryons (Stoks, Rijken 1999): Σ+p, Σ−n: quasibound state Σ+Σ+, Σ−Σ−: Eb = −1.5 to −3.2 MeV Ξ0Σ+, Ξ−Σ−: Eb = −2 to −17 MeV Ξ0Ξ0, Ξ0Ξ−: Eb = +1 to −16 MeV Ξ−Ξ−: less bound by ≈ 1 MeV update: NΞ(3S1, I = 1) with Eb = 1.56 MeV (ESC08, Nagels, Rijken, Yamamoto 2015)

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Baryon-baryon potentials: Quark-meson models

quark-meson exchange model uses confinement potential for quarks SU(3) symmetry for quark-meson coupling constants describes light hypernuclei predictions for dibaryons (Fujiwara, Suzuki, Nakamoto 2007): no bound states

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Baryon-baryon potentials: chiral effective models

• ne-boson exchange of pseudoscalar mesons plus contact

terms uses SU(3) symmetry, low-energy constants fixed to NN and NY scattering data predictions for dibaryons (Haidenbauer and Meißner 2010): Ξ0Λ: Eb = −0.43 MeV or quasibound Ξ0Σ+: Eb = −2.23 to −6.15 MeV ΞΞ: Eb = −2.56 to −7.28 MeV results depend on cutoff

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

News from Lattice Data on Dibaryons

HALQCD collaboration (Inoue et al. 2010, 2011): bound H-dibaryon with BH = 26 MeV (for mps = 469 MeV, Nf = 3) NPLQCD collaboration (Beane et al. 2010, 2011): bound H-dibaryon with BH = 13.2(1.8)(4.0) MeV and bound (Ξ−Ξ−)b state with BΞΞ = 14.0(1.4)(6.7) MeV (for mπ = 390 MeV, Nf = 2 + 1) Haidenbauer and Meißner 2011: either ΛΛ is unbound (HALQCD) or a resonant state 5 MeV below ΞN threshold (NPLQCD) Shanahan, Thomas, Young 2011, 2013: H dibaryon unbound by 26 ± 11 MeV at physical pion mass

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

nΣ− state on the Lattice

100 200 300 400 500

pLAB (MeV)

10 20 30 40 50 60

δ (degrees)

NSC97f Juelich '04 EFT

100 200 300 400 500

pLAB (MeV)

• 60
• 50
• 40
• 30
• 20
• 10

10 20 30

δ (degrees)

NSC97f Juelich '04 EFT

0.1 0.2 0.3 0.4 0.5

ρn (fm)

• 3

20 40 60 80 100

∆E (MeV) Σ

−

Nuclear matter

(Beane et al. 2012)

scattering length for singlet and triplet nΣ− (left plots) repulsive potential at nonvanishing density (right plot) at unphysical pion mass of mπ ∼ 390 MeV comparison to Nijmegen model, J¨ ulich model and effective field theory

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Hypernuclei on the Lattice

−200 −180 −160 −140 −120 −100 −80 −60 −40 −20

−B [MeV]

1+ 0+ 1+ 0+ 1+ 0+

1 2 + 1 2 + 3 2 + 1 2 + 3 2 +

0+ 0+ 0+ 0+

d nn nΣ H-dib nΞ

3He 3 ΛH 3 ΛHe 3 ΣHe 4He 4 ΛHe 4 ΛΛ He

s = 0 s = −1 s = −2 2-body 3-body 4-body deuteron nn Hdib n 1s0 n 3s1 n 1s0 n 3s1 n 3s1 p 3s1 10 27 1 10 8A 100 80 60 40 20 E MeV

L48 , p2 L48 , p1 L48 , p0 L32 , p2 L32 , p1 L32 , p0 L24 , p2 L24 , p1 L24 , p0

(Beane et al. 2013)

Light nuclei and hypernuclei on the lattice at unphysical pion mass of mπ ∼ 800 MeV and in SU(3) flavor symmetry

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

ΞΞ Dibaryon on the Lattice

(Beane et al. 2011)

bound (Ξ−Ξ−)b state with BΞΞ = 14.0(1.4)(6.7) MeV (for mπ = 390 MeV) extrapolation to physical pion mass: ΞΞ dibaryon bound by −2.56 · · · − 7.27 MeV! NSC97a-f: Nijmegen OBE model, HM: Haidenbauer and Meißner chiral EFT, Miller: SU(3) flavor symmetry arguments

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Dibaryons close to physical point

• 10

10 20 30 20 40 60 80 100 120 140 Phase Shift [degree] ECM [MeV] t=14 t=12 t=10

(Doi et al. (HAL QCD) 2015)

preliminary Nf = 2 + 1 lattice calculation at (mπ, mK) ≃ (146, 525) almost at physical masses phase shifts (left) and potential (right) for ΞΞ ΞΞ interaction with strong attraction but not enough for a bound state

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Content

1

Hyperon-Nucleon Interaction: Hypernuclei

2

Baryon-Baryon Interactions: Dibaryons

3

Finding Strange Matter

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Timeline for strange matter detection

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Sensitivity range for detecting strange matter

(Dover, talk given at PANIC meeting 1991, preprint BNL-46322)

rough coalescence estimate: production ∝ qA · λ|S|, q = Nd/Np, λ = NY/NN for a sensitivity of the experiment of 10−n: |S| + A ≤ n + 3 includes (stable) dibaryon states!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Production of hypernuclei in heavy-ion collisions

(Armstrong, Dover et al. (E864 collaboration) 2004)

production of 3

ΛH and 4 ΛH seen!

decay modes: 3

ΛH→3He+π−, 4 ΛH→4He+π−

historical note: last paper of Carl Dover (posthumous)!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Fishing hypernuclei out of the QGP at RHIC

(STAR collaboration, Science 2010)

production of 3

ΛH and its antiparticle seen

measurement of invariant mass spectrum of π− and 3He initiated follow-up experiments at GSI (FOPI) and LHC (ALICE)!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

H-Dibaryon Production Rates at the LHC

(Benjamin Doenigus for the ALICE collaboration, QM2012)

production limit for H-Dibaryons from Λpπ− mass spectrum limit is about a factor 10 below prediction from statistical model!

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

Hypernuclear production at the LHC

)

2

c )(GeV/

• π

He,

3

Invariant mass ( 2.98 2.99 3 3.01 3.02 3.03 3.04 )

2

c Entries/(2.5 MeV/ 10 20 30 40 50 60 70 80 90

Data Background Combined Fit ALICE 10-50% = 2.76 TeV

NN

s Pb-Pb

• π

He +

3

→ H

Λ 3

c < 10 GeV/

T

p ≤ 2

)

2

c )(GeV/

• π

He,

3

Invariant mass ( 2.98 2.99 3 3.01 3.02 3.03 3.04 )

2

c Entries/(2.5 MeV/ 10 20 30 40 50 60 70 80 90

Data Background Combined Fit ALICE 10-50% = 2.76 TeV

NN

s Pb-Pb

+

π + He

3

→ H

Λ 3

c < 10 GeV/

T

p ≤ 2 (ALICE collaboration 2015)

invariant mass distribution for 3He,π− dN/dy × B.R.(3

ΛH→3He,π−) = (3.86 ± 0.77(stat.) ± 0.68(syst.)) × 10−5

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

ΛΛ correlation function

0.8 0.9 1 0.1 0.2 0.3 0.4 0.5 C(Q) Q [GeV/c] Cylindrical w/ flow, +Cres(Q) λ=(0.67)2 fss2, R=2.5fm ESC08, R=2.5fm FG, R=2.5fm HKMYY, R=2.5fm STAR 0-80% (Ohnishi, Morita, Furumoto, 2015)

ΛΛ correlation function measured by STAR (Au+Au at 200 AGeV) fit with hydro expansion and correction from feed down from Σ0 and

• ther hyperons

residual suppression at high values of Q ∼ 0.4 (?)

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

ΛΛ scattering parameters

5 10 15

• 5
• 4
• 3
• 2
• 1

1 2 reff (fm) 1/a0 (fm-1) ΛΛ scattering parameters

ND NF NSC89 NSC97 ESC08c Ehime fss2 FG HKMYY STAR MFO ’15 (1/a0<-0.8 fm-1) LL (free λ) LL (λ=(0.67)2)

(Ohnishi, Morita, Furumoto, 2016)

scattering parameters for ΛΛ for different interactions STAR data without feed down corrections feed down correcions: yellow area (offset λ = 0.67) LL: Lednicky & Lyuboshits model

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Hyperon-Nucleon Interaction: Hypernuclei Baryon-Baryon Interactions: Dibaryons Finding Strange Matter

How to detect strange matter?

unique opportunity to produce and study them in heavy-ion collisions tracking down strange dibaryons by:

(A) a direct look: exotic decay tracks in TPC (B) backtracking: invariant mass spectra for bound dibaryons (C) correlations: resonances seen in correlation functions, reveals interaction potential

poised for discoveries!