1 / 57

The meson landscape

“Diquarks,Tetraquarks, Pentaquarks and no quarks”. “Diquarks,Tetraquarks, Pentaquarks and no quarks”. The meson landscape. Scalars and Glue in Strong QCD. New states beyond. Correlated Colour in Strong QCD. Weird baryons: pentaquark problems.

diallo
Download Presentation

The meson landscape

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. “Diquarks,Tetraquarks, Pentaquarks and no quarks” “Diquarks,Tetraquarks, Pentaquarks and no quarks” The meson landscape Scalars and Glue in Strong QCD New states beyond Correlated Colour in Strong QCD Weird baryons: pentaquark problems Some reflections on Pentaquarks Implications for Exotic Mesons? Frank Close IPPP 041027

  2. Colour Correlations in Chromostatics

  3. Chromostatics: Like electrostatics – unlike colours attract baryon + + + meson - +

  4. Attraction of two quarks to make a “diquark” + + Pauli maximal attraction when net spin=0 and different flavours “Scalar Diquarks” Ifthis acts as a quasi-particle………

  5. + + - - Diquark antidiquark mutually attract ……… ……Making a meson from diquarks = 2 quarks and 2 antiquarks

  6. Fall apart into qq* pairs: Broad width + + - - Flavour pattern in nonet differs from qq* Consistent with light scalar mesons Jaffe; Close Tornqvist; Maiani et al

  7. + + + + + + Three diquarks……..

  8. + + + + + + rearrange to make… e.g. a deuteron (lower energy state… … presumably)… …..not obvious in JW model with light [ud]

  9. + + + + - Lets try another way: replace the BLUE YELLOW Diquark by a REDantiquark YELLOW

  10. + + + + -

  11. us* d d u + + + + - neutron K The forces rearrange them to make e.g. a neutron and a kaon… “fall apart” = broad Or so we thought!!! 2002 discovered a (narrow) pentaquark! maybe

  12. d u d u + + + + s* - Ifthe data survive; and if this is a pentaquark…. the correlations seem to maintain their identities 100 times more stable than anticipated (expt) = two ideas on how this happens (theory) Jaffe Wilzcek Karliner Lipkin

  13. (qqq)(qq) description (Karliner, Lipkin) (qq)q(qq) description (Jaffe, Wilczek) (uds) L=1 (ud) L=0 (ud) s L=1 (ud) distance > color magnetic force JP = ½+ JP = ½+ Colour correlated models of the Q+ Pentaquark

  14. Narrow Pentaquarks (if they exist) = strong QCD correlations Jaffe Wilczek u d u d ud L=1 Q* Diquark attractions for unlike flavours = basis for pentaquark models ( not demonstrated how low mass scalar diquarks form, stability, effective bosons, consistency with other hadron spectroscopy… etc. = ?) udQ* ud L=1 Karliner Lipkin

  15. Some reflections on Pentaquarks 10

  16. Inconsistencies (I) • Width of Θ+(1540) • Two “positive” experiments: HERMES: ΓΘ= 17 9  2 MeV ZEUS: ΓΘ= 8  4 MeV • K+N PWA results indicates ΓΘ < 1 MeV • Mass of Θ+(1540)

  17. Anomalies with Theta Mass? (LEPS) F. Close and Q. Zhao, hep-ph/0404075

  18. Arndt Buccella Carlson Dyakanov Ellis Faber Giannini Huang Inoue Jaffe Karliner Lipkin Maltman Nussinov Oh Polyakov Qiang Rosner Stech Trilling U Veneziano Wilczek Xiang Yang Zhu If Theta doesn’t exist, then these (and many other theorists) should be congratulated on their creativity

  19. Mass 15

  20. Mass Fitted historically. Not calculated Dyakanov Petrov Polyakov DPP assumed N(1710) in 10bar X mass formula bizarre: q_5 10bar mass gap 1/3 m_s X pure 10bar not photoproduced from p Jaffe Wilzcek JW assumed N(1440) as (ud)(ud)dbar X width 300MeV X gamma n:gamma p = radial 56plet qqq X Delta(1670) partner Karliner Lipkin KL assume cs* 200MeV orbital to set scale X spin averaged cs* costs 500MeV, Theta= 1800MeV

  21. Mass (L=1) = 200MeV Karliner Lipkin Ds(cs*) spectrum 2.59 2.56 2.32 2.11 1.97 Ask Harry: is this cs* or DK molecule? 0+ 210 1-

  22. Mass 2.55 -2.47 2.07 2+ 1+ L=1 0+ Spin averaged masses in multiplet 400-480 1- L=0 Theta = 1750-1830 0-

  23. Jaffe Wilczek u d u d ud L=1 Q* 3/2 Spin-Orbit splitting <100MeV FC+ Dudek 1/2 udQ* L=1 ud 10bar 3/2+ unique to qqqqq* Karliner Lipkin

  24. Mass Fitted more recently or excused Weise…Wilczek…Close…Maiani…(Kochelev,Vento) m[ud] ~ m(d) ~300MeV e.g. L=2: N(1680: [ud] u) = rho_3(1700: d*u) e.g. L=1: Lambda(1405: [ud] s) = K_2(1430: ds* ) 0+ mesons \sigma 600MeV; k 800MeV; f0/a0 980MeV Theta ~ 1100 + orbital; X doesn’t explain Lambda Why (does?) [ud] get protected ….at high L … in S-wave mesons But not in S-wave baryons?

  25. Mass “calculated”: Instanton attractions: [ud]~450; (uds*) ~ 750 udQ* uds* compact stabilised by instanton forces. aids narrow width (assertion) (ud)6,1 and (ud)3,0 mix lowers mass Hogaasen Sorba; Kochelev Vento…….. Effective mixes [ud]-s* and (uds*) ud*Q ud* leaks into pions = broader width Theta only narrow 10* udQ* ud L=1 400 450 750 Theta (1600)

  26. Width 20

  27. Chiral Soliton Theta-N-K Coupling involves three unknowns A; B; C Width B F/D Set scale with g(10*) = 1-B-C NRCQM: F/D=2/3B=1/5 no ss* in N: C= 4/5 g(10*)=0 g(10*) After Ellis Karliner Prasalowicz C

  28. Width < 10 MeV experiments<1MeV Cahn Trilling; Nussinov;… Decouples from KN (small width) Strong coupling to something (strong production)  How is Theta produced? ………………enigma

  29. Production 25

  30. Inconsistencies (II) • Production rate (e.g. for Θ+(1540) ) • “Positive” experiments: SAPHIR:RΛ*(1520) ~ 0.3 HERMES: RΛ*(1520) ~ 1.6~3.5 ZEUS: RΛ*(1520) ~ 0.2 ( I estimated from RΛ ~ 0.04 ) SVD-2: RΛ*(1520) > 0.2 ( estimated by SPHINX, hep-ex/0407026) • “Negative” experiments: ALEPH: RΛ*(1520) < 0.1 BaBar: RΛ*(1520) < ~ 0.01 Belle: <0.02 HERA-B: RΛ*(1520) < 0.027~0.16 SPHINX: RΛ*(1520) < 0.02

  31. Several experimental limits in hadron production Some not restrictive yet e.g. psi(3095) to Theta Thetabar (=3080) versus LambdaLambdabar (1/100) or can be “explained away” e.g. hard to make 10 q + q* My opinion (this week) Limits in high statistics look impressive. Onus is on supporters to explain them away or find a loophole next ……….example of a possible loophole Lipkin Karliner

  32. Why seen in photons but not in high statistics hadrons? CLAS: Theta+K = N*(2.4GeV) (24ev/10bgnd) Suppose N*(uddss*) and gamma provides the ss* Problems CLAS see in gamma pi K pi N Theta N* No memory of gamma(ss*); should apply to hadrons too…..why not CDF? SPring8 and CLAS1 too low E(gamma) to make 2.4GeV N*

  33. The Mystery of the Sigma_5 • The case of the dog that didn’t bark (Sherlock Holmes) If Theta is real, why isnt Sigma_5 (or Sigma* ½+ 1660) also seen?

  34. Decays Dyakanov Petrov Polyakov; Close Dudek; Oh Kim Lee Note pKs can be + or + 30

  35. Gamma N \to K Theta Assuming s,t,u and contact diagrams

  36. Gamma N \to K Sigma5 FC-Q Zhao

  37. Sigma5:Theta photoproduction ratioinsensitive to ENERGY….. …and to the Sigma Pentaquark mixing. Sigma:Theta > 0.4 Could be 0.6 Why not seen in pKs? FC+Q Zhao 0.5

  38. Absence of Sigma_5, or even Sigma(1660)in experiments that claim Theta is a worry. HERMES (unless Theta (uds*) exists and Sigma (ud*s) doesn’t Vento) Or Theta and Sigma_5 degenerate = extra width FC Dudek unpublished on grounds of taste M(pKs)

  39. Fake Peaks in gamma N Dzierba Szczepaniak Teige N N a2/rho3 gamma 35

  40. Fake Peaks in gamma N D/F wave decay forward back to KKbar a2/rho3 gives charge asymmetry Narrow K+n Broad K-n N a2/rho3 + N K- K Same velocity NK mass 1440 “real” kinematics broadens hump…. Dzierba Szczepaniak Teige

  41. One is real (CLAS) Three are fake Can you tell which? Dzierba Szczepaniak Teige

  42. Could this also explain different nK+ and pKs masses? Different Q values for charged neutral feed into mass of fake Theta? (LEPS) Show Dalitz plots!! F. Close and Q. Zhao, hep-ph/0404075

  43. Exotic Mesons inspired by pentaquark correlations 39

  44. L=1……making exotic 1-+ mesons……et al - + L - + + - - - + - L L +/- + + Burns Close Dudek based on KL

  45. S=+2 meson = Kochelev, Lee & Vento suppresses decay width apply same logic to narrow, strangeness +2 meson near 1600 MeV Exotic Pentaquarks Exotic Mesons general problem with clustered quark models, for example triquark - diquark:

  46. Three overheads on 1-+ pi_1(1400) and pi_1(1600) as correlated q*(qqq*) \pm q(q*q*q) Burns Close Dudek

  47. Paradoxes; Enigmas;Hints of unreality Cascades (exotics) studied since BQM Beware! Why does mass vary? real (dynamic clue);statistics (non existence clue) Decouples from KN (small width) Strong coupling to something (strong production) How is Theta produced? Why seen in low statistics photoproduction but not in high statistics hadroproduction? K-Theta+ why no K+Sigma- Ks Theta+ why no Ks Sigma+ Why is production Theta/Sigma(1660) = infinity?

  48. CONCLUSION Have Weird Multiquark Demons been found? Is there a 1 MeV wide, S=+1 baryon at 1540 MeV? IfNO this is testament to the ingenuity of theorists whose models can explain it even if it doesn’t exist. Lattice QCD is almost unique in not having definitively disproved that such a state does not exist.

  49. CONCLUSION • YES • No • Keep searching Have Weird Multiquark Demons been found? Democratic voting paper/Florida counting principle

  50. This slide sponsored by Oxford University Press • A Very Short Introduction to Particle Physics A little red pocket book with no equations for physics undergraduates and your partners by Frank Close • 10 dollars at amazon.com now

More Related