Exotic hadrons production in heavy ion collisions

20
1 Exotic hadrons production in heavy ion collisions Che-Ming Ko Texas A&M University Exotic hadrons studies in HIC Thermal vs coalescence production Pentaquark Θ + ( ) Diomega (ΩΩ) 0 D sJ (2317): diquark or tetraquark Charmed tetraquark mesons and pentaquark baryons Other exotic mesons, baryons and dibaryons Supported by US National Science Foundation and the Welch Foundation udud s

Transcript of Exotic hadrons production in heavy ion collisions

Page 1: Exotic hadrons production in heavy ion collisions

1

Exotic hadrons production in heavy ion collisions

Che-Ming Ko Texas A&M University

  Exotic hadrons studies in HIC   Thermal vs coalescence production   Pentaquark Θ+( )   Diomega (ΩΩ)0   DsJ(2317): diquark or tetraquark   Charmed tetraquark mesons and pentaquark baryons   Other exotic mesons, baryons and dibaryons

Supported by US National Science Foundation and the Welch Foundation

ududs

Page 2: Exotic hadrons production in heavy ion collisions

2

Exotic hadron studies in HIC

  Θ+( ) - Randrup, PRC 68, 031903 (2003); statistical model - Letessier et al., PRC 68, 061901(R) (2003); statistical model - Chen et al., PLB 601, 34 (2004); coalescence model - Nonaka et al., PRC 69, 031902 (2004); coalescence model, elliptic flow - Not observed by STAR and PHENIX   Diomega (ΩΩ)0

- Zhang et al., PRC 61, 065204 (2000); based on chiral quark model - Pal et al., PLB 624, 210 (05); hadronic transport model   DsJ: (c ) or (c q )

- Chen et al., PRC 76, 064903 (2007); coalescence model   Θcs

+(udus ) and Tcc(ud ) - Lee et al., Eur. J. Phys. C 54, 259 (08); coalescence model

  Exotic mesons (8), baryons (8), and dibaryons (6)

- Cho et al. [ExHIC Collaboration], PRL 106, 212001 (2011); PRC 84, 064910 (2011); coalescence model

c

c

c

ududs

Page 3: Exotic hadrons production in heavy ion collisions

3

Assume thermally and chemically equilibrated system of non-interacting hadrons and resonances with density

Determine chemical freeze out temperature Tch and baryon chemical potential µB by fitting experimental data after inclusion of feed down from short-lived particles and resonances decay.

Tch~Tc

Statistical model Andronic et al, NPA 722, 167 (2006); Wheaton et al., Phys. Commun. 180, 84 (2009)

Page 4: Exotic hadrons production in heavy ion collisions

4

Quark distribution function

Spin-color statistical factor

e.g.

Coalescence probability function

Greco, Ko & Levai, PRL 90, 202102 (2003); PRC 68, 034904 (2003)

Number of hadrons with n quarks and/or antiquarks

fM(x1,x2;p1,p2) = f2(x1 - x2;p1 - p2) = exp[(x1 - x2)2 /2Δ x

2 ] × exp[{(p1 - p2)2 - (m1 - m2)2}/2Δ p

2 ]

Δ x ⋅ Δ p ≈

For baryons, Jacobi coordinates for three-body system are used.

Coalescence model

Page 5: Exotic hadrons production in heavy ion collisions

5

Θ+(udud sbar) production in heavy ion collisions

Number of Θ+ produced in quark coalescence model

Using non-relativistic distributions for quarks and harmonic oscillator wave functions for Θ+

Chen, Greco, Ko, Lee & Liu, PLB 601, 34 (2004)

NΘ = gΘpi ⋅ dσid

3 p i(2π )3Ei

fq (xi, pi) fΘ(x1⋅ ⋅ x5;p1⋅i=1

5

∏∫ ⋅ p5)

= gΘNu2Nd

2Ns

4mq

5ms

+15

⎝ ⎜

⎠ ⎟

3 / 2(4π )3 / 2σ3

V (1+ 2mqTσ2)

⎣ ⎢

⎦ ⎥

4

fq (η,y, p ⊥ ) = gqδ(η − y)exp(− p ⊥

2 /(2mqT))

fΘ(x;p) = 84 exp − y i2 /σi

2 − k i2σi

2

i=1

4

∑i=1

4

∑⎛

⎝ ⎜

⎠ ⎟

Page 6: Exotic hadrons production in heavy ion collisions

6

  About 0.5 Θ+ (σ=0.86 fm and ΓΘ=20 MeV) in central rapidity per collision, similar to predictions from statistical model (Randrup; Letessier et al.)

Au+Au @ 200 GeV

dNΘ

dτ= RQGP (τ) + σ

πN→K Θv nπnNVH + σKN→πΘv + σKN→Θv( ) nK nNVH

−ΓΘNΘ − σK Θ→πNv nK NΘ − σπΘ→KNv nπNΘ

Time evolution of Θ+(udud sbar) abundance

Page 7: Exotic hadrons production in heavy ion collisions

7

Diomega prodcution in HIC According to the chiral quark model of Zhang et al. (PRC 61, 065204 (2000)), diomega (ΩΩ)0+ is bound by ~ 116 MeV with a root-mean-square radius ~ 0.84 fm and lifetime ~ 10-10 sec.

  Cross sections for I-VI are ~ 2-25 µb and thus unimportant.   Production is dominated by two-step processes through VII, VIII (~ 50-175 µb) and IX (~ 20-50 mb).   Yield is order of magnitude smaller than in statistical or coalescence model (neglect of three-body process?) Pal, Ko & Zhang, PLB 624, 210 (05)

Page 8: Exotic hadrons production in heavy ion collisions

8

  Mass of 2317 MeV less than those predicted by quark model and QCD sum rule for two-quark state (c , p-wave) but comparable to those for four-quark state (c q , s-wave)

  Width of a few (four-quark) to a few tens (two-quark) keV from decay to Dsπ, empirically less than 4.6 MeV limited by experimental resolution.

  Observed in elementary reactions: - BABAR: from Ds+π0 inclusive invariant mass distribution in e+e- annihilation (PRL 90, 242001 (03)) - Belle: from B decay (PRL 91, 262002 (03))

DsJ(2317): Jπ=0+

Page 9: Exotic hadrons production in heavy ion collisions

9

DsJ production at RHIC

  Cross sections are for four-quark state and larger by ~9 for two-quark state.   Final yield is sensitive to the quark structure of DsJ

Chen, Liu, Nielsen & Ko, PRC 76, 064903 (2007))

Page 10: Exotic hadrons production in heavy ion collisions

10

Orbital angular momentum dependence of coalescence probability

fsw ( y , k ) = 8exp −

y 2

σ2− k 2σ2

⎝ ⎜

⎠ ⎟

f pw ( y , k ) =

163

y 2

σ2− 8 +

163

k 2σ2⎛

⎝ ⎜

⎠ ⎟ exp −

y 2

σ2− k 2σ2

⎝ ⎜

⎠ ⎟

  Hadron Wigner functions

  Coalescence factors

1gNV

4πσ 2( )3 / 2

1+ 2µTσ 2( )2≈ 0.360 for s −wave

1gNV234πσ 2( )3 / 22µTσ 2

1+ 2µTσ 2( )2≈ 0.093 for p −wave

  p-wave coalescence is suppressed by a factor of ~ 4 compared to s-wave coalescence.

Page 11: Exotic hadrons production in heavy ion collisions

11

Suppression of Λ(1520) in HIC Abelev [Star Collaboration], PRL 97, 132301 (2006)

  Measured Λ(1520)/Λ(1115) ratio is significantly smaller than thermal model prediction, but can be explained by the coalescence model after taking into account the p-wave state of strang quark in Λ(1520) (Kanada-En’yo and Meuller, PRC 74, 061901(R) (2006).

Page 12: Exotic hadrons production in heavy ion collisions

12 Works very well with 3x CB = CM = 635 mu2

u u d €

CB

mimjsi ⋅ sj[ ]∑

  Baryon mass differences

  Meson mass differences

d u €

CM

mimjsi ⋅ sj[ ]∑

Diquark

Quark-antiquark

Quark color-spin interaction and hadron masses Lee, Yasui, Liu, and Ko, EJPC 54, 259 (2008)

Page 13: Exotic hadrons production in heavy ion collisions

13

  Charm tetraquark mesons - Tcc ( ) is ~ 80 MeV below D+D* -  Coalescence model predicts a yield of ~5.5x10-6 in central Au+Au collisions at RHIC and ~9x10-5 in central Pb+Pb collisions at LHC if total charm quark numbers at mid-rapidity are 3 and 20, respectively -  Yields increase to 7.5x10-4 and 8.6x10-3, respectively, in the statistical model

  Charmed pentaquark baryons -  Θcs( ) is ~ 70 MeV below D+Σ, ~ 30 MeV below N+Ds, but ~ 8 MeV above Λ+D -  Yield is ~1.2x10-4 at RHIC and ~7.9x10-4 at LHC from the coalescence model for total charm quark numbers of 3 and 20, respectively -  Statistical model predicts much larger yields of ~4.5x10-3 at RHIC and ~2.7x10-2 at LHC

Charm exotics production in HIC Lee, Yasui, Liu & Ko Eur. J. Phys. C 54, 259 (08)

Page 14: Exotic hadrons production in heavy ion collisions

14

Decay modes of Tcc and Θcs

Page 15: Exotic hadrons production in heavy ion collisions

15

Exotic mesons, baryons and dibaryons Cho, Furumoto, Hyodo, Jido, Ko, Lee, Nielsen, Ohnishi, Sekihara, Yasui, and Yazaki [ExHIC Collaboration], PRL 106, 212001 (2011); PRC 84, 064910 (2011)

Page 16: Exotic hadrons production in heavy ion collisions

16

Parameters in fireball model & in hadron Wigner functions

σ = µω( )−1/ 2

V (τ) = π RC + vC (τ −τC ) + a /2(τ −τC )2[ ]2τc

fixed by normal hadrons

Page 17: Exotic hadrons production in heavy ion collisions

17

Exotic hadron yields at RHIC and LHC

  Most yields are sufficient large (>10-5)

Page 18: Exotic hadrons production in heavy ion collisions

18   Most exotic hadrons are abundantly produced (>10-5)

Yields of exotic hadrons at RHIC

Page 19: Exotic hadrons production in heavy ion collisions

19

Ratio of exotic hadron yields from coalescence and statistical models

  Multiquark hadrons are suppressed while hadronic molecules are enhanced in coalescence model, compared to the statistical model predictions

Page 20: Exotic hadrons production in heavy ion collisions

20

Summary

  Expected yield of Θ+(udud ) in HIC is large but it is not observed.

  Possible existence of tetraquark meson Tcc( ) and pentaquark baryon Θcs( ) due to attractive diquark spin-spin interaction

  HIC allows for the study of ΩΩ interaction and possible existence of (ΩΩ)0+

  Yield of Dsj (2317) in HIC is sensitive to its quark structure

  Yields of exotic hadrons are appreciable in HIC (>10-5)

  In the coalescence model, yields of exotic hadrons are sensitive to their structures with molecular-state configurations enhanced and multiquark configurations suppressed relative to statistical production

udc c

udusc