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Quarkonium experimental overview I

Quarkonium experimental overview I. Stephen Lars Olsen Seoul National University. France-Asia Particle Physics School, Les Houches, FRANCE October 11-12, 2011. J/ y. y ’. ϒ (1S). Outline. y ”. ϒ (4S). Lecture 1: Bound charmonium & bottomonium states and their properties. X(3872).

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Quarkonium experimental overview I

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  1. Quarkoniumexperimental overview I Stephen Lars Olsen Seoul National University France-Asia Particle Physics School, Les Houches, FRANCE October 11-12, 2011

  2. J/y y’ ϒ(1S) Outline y” ϒ(4S) Lecture 1: Bound charmonium & bottomonium states and their properties

  3. X(3872) Zb(10610) Y(3940) Y(4260) Outline Zb(10650) Lecture 2: Non-quarkonium, quarkonium-like states and the future

  4. Lecture 1 Bound charmonium & bottomonium states and their properties

  5. Constituent Quark Model 1964 The model was proposed independently by Gell-Mann and Zweig Three fundamental building blocks 1960’s (p,n,l) Þ 1970’s (u,d,s) mesons are bound states of a of quark and anti-quark: Can make up "wave functions" by combining quarks: baryons are bound state of 3 quarks: proton = (uud), neutron = (udd), L= (uds) anti-baryons are bound states of 3 anti-quarks: Λ= (uds)

  6. Make mesons from quark-antiquark Y Y=“hypercharge” = S+B Y _ _ _ us ds s d _ u +1/3 _ _ _ _ dd _ _ _ du uu ud u d _ IZ ss s _ _ sd su -2/3 _ -1/2 +1/2

  7. Ground state mesons (today) JP=0- JP=1- 498 494 892 896 K*+ K*0 135 548 783 776 776 776 r- w r0 r+ 139 139 958 f 1020 _ 494 498 K*- K*0 896 892 (p+,p0,p-)=lightest (r+,r0,r-)=lightest nr=0 nr=0 S-wave S-wave

  8. HW: Construct baryon octet and decuplet combinations of three uds triplets duu d uuu u d u d u s uus s s Finish the procedure

  9. Answer 2(8-tet)s + 10-plet  singlet dud uud ddd uud dud uud sdd sud suu sdd sud suu sud ssd ssd ssu ssu sss

  10. Ground state Baryons JP=1/2+ JP=3/2+ 939 938 M=1232 MeV 1115 M=1385 MeV 1189 1197 1192 M=1533 MeV 1315 1321 M=1672 MeV all nr=0 all S-waves all nr=0 all S-waves

  11. Are quarks real objects?or just mathematical mnemonics? 助记符 기억하는 Are quarks actually real objects?" Gell-Mann asked. "My experimental friends are making a search for them in all sorts of places -- in high-energy cosmic ray reactions and elsewhere. A quark, being fractionally charged, cannot decay into anything but a fractionally charged object because of the conservation law of electric charge. Finally, you get to the lowest state that is fractionally charged, and it can't decay. So if real quarks exist, there is an absolutely stable quark. Therefore, if any were ever made, some are lying around the earth." But since no one has yet found a quark, Gell-Mann concluded that we must face the likelihood that quarks are not real. Gell-Mann Nobel Prize 1969

  12. A prediction of the quark model:

  13. Mark I detector At SLAC’s “SPEAR” e+e- collider muon identifier tracking chamber e+ e- ~3GeV

  14. R data in June 1974 hadrons R e+ Ecm e- Big data fluctuations around 3.0 GeV Not even close to 2/3 2/3 Ecm Compilation by: L. Paoluzi Acta Physica Polonica B5, 829 (1974)

  15. after a fine energy scan near 3 GeV: A huge, narrow peak near 3.1 GeV Also seen in pNe+e-X at Brookhaven y J R=2.2 >>2/3 M(e+e-) 10 J.J. Aubert et al., PRL 33, 1404 (1974) J.E. Augustine et al., PRL 33, 1406 (1974) The “J/y” meson

  16. Another peak near 3.69 GeV y’  About 2 weeks later G.S. Abrams et al., PRL 33, 1453 (1974)

  17. Why J/y? Group leader of the Brookhaven expt Event in Mark I y’p+p- J/y e+e- Samuel C.C. Ting Mark-I detector Chinese character for Ting:

  18. Interpretation of J/y and y’ charmed-quark anticharmed-quark mesons c c c c nr=1 M=3.686 GeV nr=0 M=3.097 GeV S-wave S-wave charmed quark  q= +2/3 partner of the s-quark before 1974 after 1974 A q=+2/3rds partner of the s quark had been suggested by many theorists

  19. Charmonium mesons formed from c- and c-quarks r c c c-quarks are heavy: mc ~ 1.5 GeV  2mp velocities small: v/c~1/4 non-relativistic, undergraduate-level QM applies

  20. QM of cc mesons c c r What is V(r) ?? “derive” from QCD

  21. “Cornell” potential c c r linear “confining” long distance component V(r) slope~1GeV/fm ~0.1 fm r 1/r “coulombic” short distance component 2 parameters: slope & intercept

  22. Charmonium (cc) Positronium (e+e-) _ y’ J/y

  23. The “ABC’s” of charmonium mesons JPC quantum numbers c S=1  triplet of state S=0  singlet c c Parity (x,y,z) ↔ (-x,-y,-z) C-Parity quark ↔ antiquark J/y (y’): JPC = 1- - photon: JPC = 1- - X e+ J/y (y’) e-

  24. ABC’s part IIspectroscopic notation c c c y’ = 23S1 hc = 21S0 ’ S= spin (0 or 1) J= total ang. mom. n(2S+1)LJ J/y = 13S1 n=radial quant. nmbr L= S, P, D, F, … hc = 11S0 0, 1, 2, 3, …

  25. ABC’s part III“wave function at the origin” _ In J/y decay, the c and c quarks have to annihilate each other S-wave n=1 e+ a c c S-wave e- n=2 P-wave This only can happen when they are very near each other: S-wave Many J/y processes are  |Y(0)|2, the “wave function at the origin,” or, in the case of states with Y(0)=0, derivatives of Y(0), which are usually small. P-wave D-wave n=3

  26. Immediate questions: • Can the other meson states be found? • Why are the J/y and y’ so narrow?

  27. Finding other states What about these? These states have been identified y’ = 23S1 cc2 = 13P2 c cc1 = 13P1 c c cc0 = 13P0 c c c J/y = 13S1

  28. The Crystal Ball Detector

  29. E-dipole g transitions to 13P0,1,2 e+ y’ e- QM textbook formula: 24. e- y’ 24. 29. 26. 313. 239. 114. J/y E. Eichten et al., PRL 34, 369(1975)

  30. Crystal ball results y’gX e+ y’ e- y’ Eg Crystal Ball expt: Phys.Rev.D34:711,1986. “smoking gun” evidence that quarks are real spin=1/2 objects J/y

  31. y’gcc0 radiative transition Expect 1+cos2q BESII PRD 70, 092004 (2004)

  32. Discovery of the P-wavestates (cc0,1,2) convinced everyone quarks were real e- y’ Eg J/y Crystal Ball expt: Phys.Rev.D34:711,1986.

  33. Immediate questions: Done! • Can the other meson states be found? • Why are the J/y and y’ so narrow?

  34. Problems with the quark model: • Individual quarks are not seen • why only qqq and qq combinations? • violation of spin-statistics theorem?

  35. W- s-1/3 s-1/3 s-1/3 three s-quarks in the same quantum state Das ist verboten!!

  36. The strong interaction “charge” of each quark comes in 3 different varieties Y. Nambu M.-Y. Han W- s-1/3 s-1/3 1 2 s-1/3 3 the 3 s-1/3 quarks in the W- have different strong charges & evade Pauli

  37. Attractive configurations Baryons: Mesons: eijk eiejek i ≠ j ≠ k i j i dij ei ej j k same as the rules for combining colors to get white: add 3 primary colors-or-add color+complementary color quarks: eiejek color charges antiquarks: anticolor charges ei ej ek eijkeiejek dijei ej

  38. Quantum Chromodynamics er eb eg QED: scalar charge e QCD triplet charge: ej aQED Non-Abelian extension of QED as gij single photon eight “gluons” ei QCD gauge transform QED gauge transform   + i ali Gi   + ie A 8 vector fields (gluons) 1 vector field (photon) eight 3x3 SU(3) matrices

  39. Vacuum polarization QED vsQCD QED 2nf 11CA QCD in QCD: CA=3, & this dominates as increases with distance

  40. QED: photons have no charge coupling decreases at large distances QCD: gluons carry color charges gluons interact with each other coupling increases at large distances a Coupling strengths distance

  41. Test QCD with 3-jet events(& deep inelastic scattering) as gluon rate for 3-jet events should decrease with Ecm

  42. “running” as as~1/4 short distance Large distance MJ/y

  43. Color explains the discrepancy in R & color Each quark has 3 colors

  44. J/y R=2.2 >>2/3 10

  45. why are the J/y and y’ so narrow? 2 3 4 Ecm

  46. How does the J/y (y’) decay? c c as C=- as gij C=- gij c gkl as C=- c violates color symmetry violates C parity c as gij Lowest-order allowed QCD process: • suppressed by as3 as gkl as This is called “OZI”* suppression *Okubo-Zweig-Iizuka gmn c

  47. How wide is the J/y (& y’)? J/y y’ The observed widths of these peaks are due entirely to experimental resolution, which is typically a few MeV

  48. Determining the J/y (& y’) widths Mark-I PRL 34, 1357 (1975) cross section for e+e-  J/yX e+ X=hadrons X Gee GX e- X=m+m- X=e+e- 2009 values 4 eqns, 4 unknowns

  49. e+e- hadrons at higher Ecm:a 3rd peak: the y” (y(3770)) Gtot ~150x bigger y’ 2009 values y” Gee ~20x smaller y” LGW PRL 39, 526 (1977)

  50. Why is Gtot (y”) much bigger? “charmed” mesons New decay channel is available: y”DD c D D0 or D+ q y” c q (=u or d) c no “OZI” suppression q D 2mD “open charm” threshold c D0 or D- (My”=3775 MeV ) 2mD+=3739 MeV 2mD0 =3729 MeV “Fall apart” Decay modes (My’=3686 MeV )

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