1 / 19

Lattice QCD searches for tetraquarks / mesonic molecules (light scalar mesons & XYZ)

Explore the quest for exotic states in lattice QCD with a focus on tetraquarks and mesonic molecules. Learn about observed resonances, hidden charm states, and the distinction between tetraquarks and molecules.

derrickt
Download Presentation

Lattice QCD searches for tetraquarks / mesonic molecules (light scalar mesons & XYZ)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lattice QCD searches for tetraquarks / mesonic molecules (light scalar mesons & XYZ) Excited QCD 2010, Slovakia SasaPrelovsek University of Ljubljana and Jozef Stefan Institute, Slovenia [sasa.prelovsek@ijs.si] In collaboration with: C.B. Lang, Keh-Fei Liu, N. Mathur, D. Mohler, M. Limmer and T. Draper Lattice 09

  2. examples Subject of study • Some of observed resonances • hidden charm states X,Y,Z • scalars s(600), k(800), a0(980), f0(980) • are candidates for exotic states like • Presented lattice criteria do no distinguish between tetraquarks / molecules: • when saying “tetraquarks” I have in mind both types. Conveying present status of lattice QCD simulations concerning whether tetraquarks exist. Lattice 09

  3. Correlator and physical states n • Compute correlation function in lattice QCD using interpolators • with desired JPC and flavor • Which physical • states n contribute? • Two-particle scattering states • have discrete spectrum Lattice 09

  4. Task: is there any state in addition to tower of scattering states? One-particle (tetraquark) state vs. Two-particle (scattering) state illustration Essential to look for few excited states in addition to the ground state ! Resonances have been sucessfully extracted in simulations of toy models: Sasaki&Yamazaki (2006) Lang & Gattringer (1993) Lattice 09

  5. Finding physical states n: • Easy to extract ground state E1 : • many lattice simulation determine only ground state from a single correlator • Essential to extract few excited states in addition to ground state • Multi-exponential fits to extract several En are unstable • Generalized eigenvalue problem allows determination of [Luscher, Wolf] [Blossier, Sommer, Mendes…] Lattice 09

  6. Recent simulation: is s(600)tetraquark ?[S.P., K.F. Liu, Lang, Mohler, Limmer, Draper, Mathur, arXiv: 0910.2749]first dynamical simulation aimed at tetraquarks tetraquarkscattering st. interpolators attractive I=0 s =udud ? p p 5: repulsive I=2 no resonance expected pp 3: To extract states with four valence quarks: we omit disconn.contractions in I=0,1/2 (as all previous lattice sim.) p(1)p(-1) p(1)p(-1) Such s would have strong tetraquark component, but it can also have qq component. Needs confirmation from independent simulation ! p(0)p(0) p(0)p(0) & s ? Lattice 09

  7. Recent simulations: is k(800)tetraquark ?[S.P., Liu, Lang, Mohler, Limmer, Draper, Mathur, arXiv: 0910.2749] tetraquarkscattering st. interpolators attractive I=1/2 k =udud ? Kp 5: repulsive I=3/2 no resonance expectedKp 3: K(1)p(-1) K(1)p(-1) Such k would have strong tetraquark component, but it can also have qq component . Needs confirmation! K(0)p(0) & k ? K(0)p(0) Lattice 09

  8. [Niu, Liu, Shen, Gong, PRD80 (2009) Mathur et al., PRD76( 2007) S.P. & Mohler, PRD 79 (2009)] Available lattice methods to distinguish: - one-particle (tetraquark) states - two-particle (scattering) states Trivial to derive for two non-interacting particles L-dependence of <Oi |n> Lattice 09

  9. Available lattice methods to distinguish (cont.): - one-particle (tetraquark) states - two-particle (scattering) states [S.P. & Mohler, PRD 79 (2009)] One-particle Two-particles B) Time -dependence of correlators at finite T Lattice 09

  10. [Sasaki, Yamazaki (2006) Liuming Liu, PoS(lat09) 099] Available lattice methods to distinguish (cont.): - one-particle (tetraquark) states - two-particle (scattering) states a mu/d Energy shifts precise simulations can determine Bound state Scattering state (attractive) Lattice 09

  11. Previous simulations: is stetraquark? • Kentucky coll, [Mathur et al, PRD76 (2007)] • quenched , overlap fermions • Single I=0 interpolator • three states with sequential Bayes method; • needs confirmation using eigenvalue method p(1)p(-1) s ? p(0)p(0) Lattice 09

  12. Previous simulations: is stetraquark?These simulations extract only the ground state • Suganuma et al. (2007) • quenched • extract ground state from one interpolator • conventional and non-conventional (hybrid) boundary conditions • ground state is scattering • no observation for tetraquark for • Alford & Jaffe (2000): slight indication for tetraquark • Loan et al.[Loan, Luo, Lam: 0809.5121, 0907.3609] , Scadron70, February 2008

  13. Hidden charm: XYZAll these simulations extract only the ground state • X(3872), Y(4260), …. [T.-W. Chiu & T.-H. Hsieh, 2005-2007 ] • quenched , overlap fermions, relativistic charm • 0.4 ms < mq < mc, mp>430 MeV • a=0.09 fm, L=1.8 fm, 2.2 fm • Ground state from single correlators Lattice 09

  14. Is X(3872) tetraquark/molecule ? • X(3872): JPC=1++ • [Chiu & Hsieh, • PLB646 (2006) 95,PRD73 (2006) 111503] possible issue: scattering should be found at the same energies, before tetraquarks can be trusted Discovered by CDF in 2009 Lattice 09

  15. Is Y(4260) tetraquark/molecule ? • JPC=1-- states • [Chiu & Hsieh, PRD73 (2006) 094510] possible issue: near by scattering states should be found, before tetraquarks can be trusted Lattice 09

  16. [Luscher 1986, 1991, Sasaki, Yamazaki :PRD74, 114507] Liuming Liu, PoS(lat09) 099] Available lattice methods to distinguish (again): - one-particle (tetraquark) states - two-particle (scattering) states a mu/d Energy shifts Only precise simulations can determine them Bound state Scattering state (attractive) Lattice 09

  17. Is X(3872) tetraquark/molecule ? • X(3872) [Liuming Liu, PoS(lat09)099 ] • dynamical , staggered sea • extract ground state from single correlator Many scattering lenghts determined by Liu (not with purpose of looking for tetraquarks) [see also Yokokawa et al, PRD74(2006)034504] a mp Change of sign in a: possible indication for bound state related to X(3872) Lattice 09

  18. Is Z+(4430) tetraquark/molecule ? • Z+(4430) [Meng et al., PRD80 (2009) 034503] • JPC unknown • near to D* D1 threshold: m(D*) + m(D1)= 4430 MeV • suspected to be D* D1 molecule • 1- 1+ • ground state energy determined from correlator • attractive interaction , but no change in sign of scattering lenght • authors suspect that interaction is no strong enough for bound state Lattice 09

  19. Conclusions • Do light scalar mesons s and k have tetraquark component? • We find two light states in I=0 and I=1/2 channels. One is the scattering state, while the other state may be candidate for s or k with strong tetraquark component. Confirmation is needed before firm conclusion! • Ultimate study would need to take into account mixing • and the interpolators have to cover all these Fock components. Then one could determine the fraction of physical states in terms of various Fock components. • Are some of hidden charm states XYZ tetraquarks/molecules? • There is some indication for tetraquark/molecular structure of • X(3872), Y(4260), Y(4140) from the lattice, but much more work is needed. • Few excited states would have to be extracted in addition to the ground state to make • reliable identification for tetraquark/molecular states. Lattice 09

More Related