from Heavy Ion Collisions New Frontiers in QCD 27-28 October 2011 - - PowerPoint PPT Presentation

Multiquark hadrons from Heavy Ion Collisions

New Frontiers in QCD

27-28 October 2011 Yonsei University

Sungtae Cho

Institute of Physics and Applied Physics Yonsei University

− This talk is based on

Identifying Multiquark Hadrons from Heavy Ion Collisions, ExHIC Collaboration, Phys. Rev. Lett. 106, 212001 (2011) Studying Exotic Hadrons In Heavy Ion Collisions, ExHIC Collaboration, arXiv: 1107.1302

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Outline

− Introduction − The statistical model − Hadronization in heavy ion collisions − The coalescence model − Results − Conclusion

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Introduction

− Normal hadrons

: Mesons and Baryons

− Multiquark hadrons

i) H dibaryon and scalar tetra quark (1976) hadronic molecule (1990) ii) Hadronic molecules & multiquark states Belle (2003) BaBar (2003)

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) 980 ( f

) 3872 ( X

) 2317 (

sJ

D

K K

Introduction

− Normal hadrons

: Mesons and Baryons

− Multiquark hadrons

i) H dibaryon and scalar tetra quark (1976) hadronic molecule (1990) ii) Hadronic molecules & multiquark states Belle (2003) BaBar (2003)

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) 980 ( f

) 3872 ( X

) 2317 (

sJ

D

K K

c c q q D D D D , ,

* *



s c q q s c DK , , 

− The purpose of this work

i) To estimate the possibility of observing predicted exotics with/without heavy quarks in heavy ion collision experiment ii) To find a possible solution to a problem of identifying hadronic molecular states and/or hadrons with multiquark components

− We focus on hadron production yields

i) Normal hadron (light quark hadrons) production yields are well described by the statistical model ii) Many aspects of the heavy ion collision experimental results can nicely be explained by the coalescence model

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The statistical model

− Hadron yield ratios at RHIC

• A. Andronic, P. Braun-Munzinger, and J. Stachel, Nucl. Phys. A 772, 167 (2006)

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− The thermally equilibrated system

Fugacity i) The hadronization temperature and the chemical potential

are determined from the experimental data ii) We expect the statistical model to play its important role again in describing the expected multiquark hadron yields produced at heavy ion collision experiment

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 

s s B B c c

n n n n c

e

 

 

 





 

 

/ 1 2 2

1 2

H i T

E i i H i

e dp p g V N  

2 2 i i i

p m E  

Hadronization in heavy ion collisions

− The fragmentation picture

i) A parton spectrum relates

the probability for a parton to hadronize into a hadron, carrying a fraction z<1 of the momentum of the parent parton. ii) The puzzle in antiproton /pion ratio Requires a rescaling for a fraction z for all hadrons

• V. Greco, C. M. Ko, and P. Levai,
• Phys. Rev. Lett. 90, 202302 (2003)

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− Coalescence vs. fragmentation

i) There must be a competition : A fragmentation dominates at large transverse momenta and a coalescence prevails at lower transverse momenta

vs.

− The coalescence picture

i) The quark number scaling of the elliptic flow of identified hadrons ii) The yield of antihyperons recently discovered in heavy ion collision at RHIC

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z p p

h T Frag T

 n p p

h T Coal T



The coalescence model

− Yields of hadrons with n constituents

i) Wigner function : Coalescence probability function ii) Covariant phase space density

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) , , : , , ( ) , ( ) 2 ( 1

1 1 1 3 3 n n W n i i i i i i i i Coal

p p x x f p x f E p d d p g g N  

 

       



 





                

n i n n n n y p i

y x y x y x y x e dy

i i

1 1 1 1 1 *

2 , , 2 2 , , 2    

) , , : , , (

1 1 n n W

p p x x f  

i i i i i i i

N p x f E p d d p  



) , ( ) 2 (

3 3

 

− The coalescence model can

i) explain both the quark and hadron coalescence

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) , , : , , (

1 1 n n W

p p x x f      

 

    g N Coal

− The coalescence model can

i) explain both the quark and hadron coalescence

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) , , : , , (

1 1 n n W

p p x x f      

 

    g N Coal

c c

) 3872 ( X

c c q q

*

D D

− The coalescence model can

i) explain both the quark and hadron coalescence ii) consider the internal structure of hadrons

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360 . ~ ) 2 1 ( ) 4 (

2 2 / 3 2 i i i i i

T V g N     093 . ~ ) 2 1 ( 2 3 2 ) 2 1 ( ) 4 (

2 2 2 2 / 3 2

       

i i i i i i i i i

T T T V g N        029 . ~ ) 2 1 ( 2 15 8 ) 2 1 ( ) 4 (

2 2 2 2 2 / 3 2

       

i i i i i i i i i

T T T V g N       

) , , : , , (

1 1 n n W

p p x x f      

 

    g N Coal

c c

) 3872 ( X

c c q q

*

D D

− Final results − The quark coalescence

: Reference hadrons -

− The hadron coalescence

: The relation between the binding energy and the root mean square radius

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), 1115 (  ) 2286 (

c



2 2

2 . . a E B   

2

2 2

a r 

2

2 3 r   

 

  

         

n j l n i i i i i i i i i i i i Coal h

i

T T l l T V g N g N

1 1 1 2 2 2 2 / 3 2

) 2 1 ( 2 ! )! 1 2 ( ! )! 2 ( ) 2 1 ( ) 4 (       

  

i i

1 



 

 i j j i i

m m 1 1 1

1



Results

− Summary of multiquark hadrons considered

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− Estimated multiquark hadron yields at RHIC and LHC

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− The loosely bound exotic hadron molecules are more produced − Normal hadron zone − The exotic multiquark hadrons become suppressed

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Stat i Coal molecule i

N N , 2  2 2 .

,

 

Stat i Coal normal i

N N 2 .

,



Stat i Coal multiquark i

N N

− Comparison to experimental data

i) Fortunately, STAR Collaboration has a preliminary measurement for P. Fachini [STAR Collaboration], Nucl. Phys. A 715, 462 (2003) ii) Can we say whether is a tetraquark hadron or a hadronic molecule? :

4-7 October 2011 GSI QWG2011, 8th International Workshop on Heavy Quarkonium 19

) 980 ( f

K K

2 . ~

) 980 ( 

N N f

) 980 ( f

− Comparison to experimental data

i) Fortunately, STAR Collaboration has a preliminary measurement for P. Fachini [STAR Collaboration], Nucl. Phys. A 715, 462 (2003) ii) Can we say whether is a tetraquark hadron or a hadronic molecule? : At least, must not be a tetraquark hadron

4-7 October 2011 GSI QWG2011, 8th International Workshop on Heavy Quarkonium 20

) 980 ( f

K K

2 . ~

) 980 ( 

N N f

) 980 ( f ) 980 ( f

8

) 980 (

 

f

N



Conclusion

− Exotic hadrons in relativistic heavy ion collisions

i) The yields of exotic hadrons are large enough to be measurable in experiments : Relativistic heavy ion collisions can provide an

• pportunity to search for exotic hadrons

ii) The probability to combine n quarks into a compact region is suppressed as n increases iii) The yield of a hadron in relativistic heavy ion collision reflects its structure : Therefore, yields can be used to discriminate the different pictures for the structure of exotic hadrons

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Backup slides

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− Time evolution of quark-gluon plasma

• J. D. Bjorken, Phys. Rev. D 27, 140 (1983)

i) Collision ii) Pre-equilibrium : QGP iii) Hadronization : Mixed phase iv) Freeze-out : Hadron gas

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2 2

z t   

− Time evolution of exotics : DsJ(2317)

• L. W. Chen, C. M. Ko, W. Liu, and M. Nielson, Phys. Rev. C 76, 014906 (2007)

i) Time evolution of the DsJ(2317) meson abundance in central Au+Au collision at =200 GeV ii) The yield of the DsJ(2317) meson increases during the hadronic evolution in the coalescence model iii) The yield decreases or remains almost unchanged depending

• n whether the DsJ(2317) meson

is a two-quark or a four-quark meson

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NN

s

− Quark coalescence

: Reference hadrons -

− Hadron coalescence

: The relation between the binding energy and the root mean

square radius

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), 1115 ( 

) 2286 (

c



Stat Stat Stat total Stat

C C C C

N N N N

) 2520 ( ) 2455 ( ) 2286 ( , ) 2286 (    

   ) ( 67 .

, ) 2286 ( ) 2625 ( c total Coal Stat

C C

N N 

 

   , 519MeV

s 

 MeV

c

385  

2 2

2 . . a E B    2

2 2

a r 

2

2 3 r   

) 1405 ( 2 ) 1405 ( ) 1405 (

2 3

  

  r   MeV 5 . 20 

− Summary of all exotic hadrons considered

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− Estimated hadrons yields at RHIC and LHC

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− Graphs

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