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Studying Strong Interactions at Densities

Studying Strong Interactions at Densities. Kyungil Kim. New Frontiers in QCD, October 28th, 2011. Based on K. Kim, D. Jido , S.H . Lee PRC 84(2011)025204 K. Kim, Y . Kim, S. Takeuchi, T. Tsukioka PTP 126(2011)735. Introduction. <The QCD Phase Diagram>. October 28 th 2011.

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Studying Strong Interactions at Densities

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  1. Studying Strong Interactions at Densities Kyungil Kim New Frontiers in QCD, October 28th, 2011 Based on K. Kim, D. Jido, S.H. Lee PRC 84(2011)025204 K. Kim, Y. Kim, S. Takeuchi, T. Tsukioka PTP 126(2011)735

  2. Introduction <The QCD Phase Diagram> October 28th 2011 2/32

  3. Introduction • Quark Number Susceptibility with Finite Quark Mass in Holographic QCD • Sudden increase of quark number fluctuation near phase transition • Quark number susceptibility is suppressed by finite quark mass. • Diquarks in Hadron Structures • Using QCD sum rules, we will study properties of diquark structure in hadrons. • It will give a chance to glance at extremely high density region. October 28th 2011 3/32

  4. Quark Number Susceptibility with Finite Quark Mass in Holographic QCD

  5. AdS/CFT Correspondence <AdS metric in 5D> October 28th 2011 5/32

  6. AdS/QCD Model – Bottom-Up Approach Ref. Erlich, Katz, Son, Stephanov PRL 95(2005)261602 Rold and Pomarol NPB 721(2005)79 Domokos and Harvey, Phys.Rev.Lett.99:141602(2007) The action of model, where, AdS5 space is compactified such that Solving the vector field equation of motion at zero momentum yields must be proportional to the quark chemical potential In generalized gauge symmetry to October 28th 2011 6/32

  7. The Hawking-Page Transition Geometry Confinement phase Thermal AdS Deconfinement phase AdS Black Hole The periodicity The Hawking temperature The black hole horizon The Euclidean gravitational action October 28th 2011 7/32

  8. Quark Number Susceptibility Ref. Cheng et al. PRD 79, 074505 (2009) <The pressure> = Grand potential <The definition of susceptibility for various charge> Under conditions met in RHIC and LHC the net baryon number is small and QCD at vanishing chemical potential provides a good approximation. October 28th 2011 8/32

  9. Deformed AdS Space The deformed AdS Black Hole Ref. Y.Kim, T.Misumi, and I.j.Shin [arxiv 0911.3205] <The back-reacted metric> where, <The Hawking temperature for black-hole> where, October 28th 2011 9/32

  10. Quark Number Susceptibility <The 5D action for U(1) gauge field> with gauge choice, 5D gauge coupling constant The Fourier decomposition <The equation of motion for A_t> October 28th 2011 10/32

  11. Quark Number Susceptibility <The quark susceptibility from hydrodynamic approach> <The quark susceptibility from thermodynamics> October 28th 2011 11/32

  12. Quark Number Susceptibility <The quark number susceptibility in deformed AdS> October 28th 2011 12/32

  13. Quark Number Susceptibility in D3/D7 <The black D3-brane background> <The DBI action for D7 brane> October 28th 2011 13/32

  14. Quark Number Susceptibility <The quark mass and the density in D3/D7 model> <The number of quarks> October 28th 2011 14/32

  15. Quark Number Susceptibility in D3/D7 <The quark number susceptibility in D3/D7 Model> October 28th 2011 15/32

  16. Summary & Conclusion • We can have similar results in holographic QCD with lattice calculation in quark number susceptibility calculations. • At bottom-up approach, two ways to obtain the quark number susceptibility give us same result. • Both the bottom-up approach and the top-down approach give the same behavior that the quark number fluctuation is suppressed by the finite quark mass. October 28th 2011 16/32

  17. Diquarks in Hadron Structures

  18. Motivation : Di-quark Structures in Hadrons SHLee and S.Yasui : EPJ C (2009) <Diquark inside baryons> <Quark-antiquark inside mesons> October 28th 2011 18/32

  19. Motivation : Di-quark Structures in Hadrons <Tetraquark> q u q Vs. u q d d q <Pentaquark> q u u d s <H Dibaryon> Di-quark structure has a important rolein high density phase. d s u s d u October 28th 2011 19/32

  20. Introduction: QCD Sum Rules <Two-point correlation function> <The operator product expansion> <Dispersion relation> ∼ Spectral Density <Borel Transformation> October 28th 2011 20/32

  21. Λ Baryons d u s Ref. PDG <Current for Λ > Scalar diquark field Gauge invariant Lagrangian for diquarkfield October 28th 2011 21/32

  22. Λ Baryons Gauge invariant Lagrangian for diquarkfield Propagator of diquark field Free parameters! The relation between diquark condensate and gluon condensate OPE terms October 28th 2011 22/32

  23. QCDSR with Di-quark fields OPE Result October 28th 2011 23/32

  24. Λ Baryons Parameter Set ( ms=0.12GeV, mΛ =1.115GeV) October 28th 2011 24/32

  25. Λ Baryons <Lambda_b sum rule> <Lambda_c sum rule> October 28th 2011 25/32

  26. Nucleons Neutron u d d Proton d u u Necleons doesn’t have “good” diquark structures inside. -> We need to consider quark-diquark interactions. October 28th 2011 26/32

  27. Scalar meson Scalar meson as a tetraquark (ud-diquark field) q q q q October 28th 2011 27/32

  28. Summary & Conclusion • The QCD sum rule approach with a diquark field gives a good result for Lambda. • We can have a diquark mass and condensate values from Lambda. • These parameters give good masses for Lmabda_c and Lambda_b. • We tried this approach to nucleon and scalar meson (tetraquark). • We have reasonable results with “bad” diquark structures inside those particles. October 28th 2011 28/32

  29. Summary & Outlook

  30. Summary • The AdS/QCD model is useful to study the physics near phase transition. • We can have similar results in holographic QCD with lattice calculation in quark number susceptibility calculations. • Diquark pictures for hadrons are successful. • We now try to apply this approach to other particles which are expected to have “good” diquark structure. (tetraqaurk, pentaquark, H-dibaryon, …) • By extended work to H-dibaryon, we expect to glance at high density region. October 28th 2011 30/32

  31. Outlook <FAIR at GSI> <KoRIA Project> October 28th 2011 31/32

  32. Thank you very much!!

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