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New types of sub-atomic particles Stephen L. Olsen University of Hawai’i uc u ccc u d u s d
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History: (hadrons) 1930’s: proton & neutron..all we need??? 1950’s: , , , , , … “Had I foreseen that, I would have gone into botany” – Fermi 1960’s: The 8-fold way “3 quarks for Müster Mark” 1970’s add charmed particles 1980’s & beauty 1990’s & (finally?) top chadwick Fermi Gell-Mann RichterTing Lederman PetersJones Zweig
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Hadron “zoo” mesons baryons
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Quarks restore economy ( & rescue future Fermis from Botany?) (& 3 antiquarks) Baryons: qqq Mesons: qq p: u +2/3 p: u -2/3 +:+: d -1/3 u +2/3 d +1/3 u -2/3 d +1//3 u +2/3 -:-: u -2/3 d +1/3 s +1/3 u +2/3 d -1/3 s -1/3 M. Gell-Mann 3 quarks Zweig
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Fabulously successful, but… quarks are not seen why only qqq and qq combinations? What about spin-statistics?
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s -1/3 2 of these s-quarks are in the same quantum state Das ist verboten!!
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The strong interaction “charge” of each quark comes in 3 different varieties Y. Nambu O. Greenberg s -1/3 the 3 s -1/3 quarks in the - have different color charges & evade Pauli --
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QCD: Gauge theory for color charges generalization of QED + i e A + i i G i QED gauge Xform QCD gauge Xform eight 3x3 SU(3) matrices 8 vector fields (gluons) 1 vector field (photon) scalar charge: e isovector charge: erebegerebeg QED QCD Nambu Gell-Mann & Fritzsch
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Attractive configurations ijk e i e j e k i ≠ j ≠ k ij e i ejej same as the rules for combining colors to get white : add 3 primary colors or add color+complementary color antiquarks: anticolor charges Hence the name: Quantum Chromodynamics quarks: e i e j e k color charges ejej eiei ekek
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Difference between QED & QCD QED: photons have no charge QCD: gluons carry color charges gluons interact with each other
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QED QCD difference Coupling strength distance
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Test QCD with 3-jet events (& deep inelastic scattering) rate for 3-jet events should decrease with E cm gluon ss
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“running” s Why are these people smiling?
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Probe QCD from other directions non-qq or non-qqq hadron spectroscopies: Pentaquarks: e.g. an S=+1 baryon (only anti-s quark has S=+1) Glueballs: gluon-gluon color singlet states Multi-quark mesons: qq-gluon hybrid mesons uc u c cc u d u s d
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Pentaquarks “Seen” in many experiments BaBar CDF but not seen in just as many others High interest: 1 st pentaquark paper has ~500 citations Belle BES
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Experimental situation is messy (many contradictory results) NA49 pp @ E cm =17 GeV (fixed tgt) (PRL92, 052301: 237+ citations!) COMPASS p @ E =160 GeV (fixed tgt) 1862 ± 2 MeV FWHM = 17 MeV = 5.6 (1862): qqssd 100s of (1530)s but no hint of (1862) hep-ex/0503033
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Pentaquark Scoreboard Positive signals Negative results Also: Belle Compass L3 Yes: 17 No: 17
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Existence of Pentaquarks is not yet established
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This talk: search for non-standard mesons with “hidden charm” standard cc mesons are: –best understood theoretically –narrow & non overlapping c + c systems are commonly produced in B meson decays. b c c s V cb cos C CKM favored W-W- cc uc u c (i.e containing c & c)
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Thanks to KEKB we have lots of B mesons (>1M BB pairs/day) >1fb -1 /day Design: 10 34
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Is the X(3872) non-standard? B K J/ M( J ) ’ J/ X(3872) J/ S.K. Choi et al PRL 91, 262001
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Its existence is well established seen in 4 experiments X(3872) CDF X(3872) D0 hep-ex/0406022 9.4 11.6
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Is it a cc meson? These states are already identified 3872 MeV Could it be one of these?
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no obvious cc assignment 3872 c ” h c ’ c1 ’ 2 c2 3 M too low and too small angular dist’n rules out 1 J/ way too small c too small;M( ) wrong c & DD) too small c should dominate SLO hep-ex/0407033
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go back to square 1 Determine J PC quantum numbers of the X(3872) with minimal assumptions
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J PC possibilities (for J ≤ 2) 0 -- exotic violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2- -(2)2- -(2) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed
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J PC possibilities 0 -- ruled out; J P =0 +,1 - & 2 + unlikely 0 -- exotic violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2- -(2)2- -(2) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed
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Areas of investigation Search for radiative decays Angular correlations in X J/ decays Fits to the M( ) distribution Search for X(3872) D 0 D 0 0
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Search for X(3872) J/
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Kinematic variables CM energy difference: Beam-constrained mass: B K J B K J B B ϒ (4S) E cm /2 ee ee M bc EE
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Select B K J/ B K c1 ; c1 J/ X(3872)? 13.6 ± 4.4 X(3872) J/ evts (>5 significance) M( J/ ) Bf(X J/ ) Bf(X J/ ) =0.14 ± 0.05 M bc
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Evidence for X(3872) J/ reported last summer hep-ex/0408116) 12.4 ± 4.2 evts B-meson yields vs M( ) Br(X 3 J/ ) Br(X 2 J/ ) = 1.0 ± 0.5 Large (near max) Isospin violation!!
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C=+1 is established B J/ only allowed for C=+1 same for X ” ”J/ (reported earlier) M( ) for X J/ looks like a
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J PC possibilities (C=-1 ruled out) 0 -- exotic violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2 - - ( 2 ) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed
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Angular Correlations K J/ J=0 X 3872 J z =0 z
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Strategy: for each J PC, find a distrib 0 if we see any events there, we can rule it out Rosner (PRD 70 094023) Bugg (PRD 71 016006) Suzuki, Pakvasa (PLB 579 67)
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Use 250 fb -1 ~275M BB prs exploit the excellent S/N Signal (47 ev) Sidebands (114/10 = 11.4 ev) X J/ ’ J/
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0 -+ 0 -+ : sin 2 sin 2 safe to rule out 0 -+ |cos | |cos | 2 /dof=34/9 2 /dof=18/9
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0 ++ ll In the limit where X(3872), , & J/ rest frames coincide: d /dcos l sin 2 l rule out 0 ++ 2 /dof = 41/9 |cos l |
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1 ++ ll 1 ++ : sin 2 l sin 2 K 1 ++ looks okay! compute angles in X(3872) restframe |cos l | 2 /dof = 11/9 |cos | 2 /dof = 5/9
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J PC possibilities (0 -+ & 0 ++ ruled out) 0 -- exotic violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2 - - ( 2 ) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed
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Fits to the M( ) Distribution X J/ in P-wave has a q* 3 centrifugal barrier X J/ q*
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M( ) can distinguish -J/ S- & P-waves S-wave: 2 / dof = 43/39 P-wave: 2 / dof = 71/39 q* roll-off q* 3 roll-off (CL=0.1%) (CL= 28%) Shape of M( ) distribution near the kinematic limit favors S-wave
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Possible J PC values (J -+ ruled out) 0 -- exotic violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2 - - ( 2 ) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed
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Search for X D 0 D 0 0
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Select B KD 0 D 0 0 events | E| 11.3±3.6 sig.evts (5.6 ) Bf(B KX)Bf(X DD )=2.2 ± 0.7 ± 0.4x10 -4 Preliminary D *0 D 0 0 ? M(D 0 D 0 0 )
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X DD rules out 2 ++ 1 ++ : DD in an S-wave q* 2 ++ : DD in a D-wave q* 5 Strong threshold suppression
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Possible J PC values (2 ++ ruled out) 0 -- exotic violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2 - - ( 2 ) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed 1 ++
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can it be a 1 ++ cc state? 1 ++ c1 ’ –Mass is ~100 MeV off – c1 ’ J/ not allowed by isospin. Expect: Bf( c1 ’ J/ )<0.1% BaBar measurement: Bf(X J/ )>4% 3872 - ( c1 ’ J/ ) / ( c1 ’ J/ ) Theory: ~ 40 Expt: 0.14 ± 0.05 c1 ’ component of the X(3872) is ≤ few %
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Intriguing fact M X3872 =3872 ± 0.6 ± 0.5 MeV m D0 + m D0* = 3871.2 ± 1.0 MeV lowest mass charmed meson lowest mass spin=1 charmed meson X(3872) is very near DD* threshold. is it somehow related to that?
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hh bound states (hadronium)? pn DD* deuteron: 2 loosely bound qqq color singlets with M d = m p +m n - hadronium (dueson) : 2 loosely bound qq color singlets with M = m D + m D* - attractive nuclear force attractive force?? There is lots of literature about this possibility N. Tornqvist hep-ph/0308277 u c u c
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X(3872) = D 0 D* 0 bound state? J PC = 1 ++ is favored M ≈ m D0 + m D0* Maximal isospin violation is natural ( & was predicted) : |I=1; I z = 0> = 1/ 2 (|D + D* - >+ |D 0 D* 0 >) |I=0; I z = 0> = 1/ 2 (|D + D* - > - |D 0 D* 0 >) |D 0 D* 0 > = 1/ 2 (|10> - |00>) (X J/ ) < (X J/ ) was predicted Equal mixture of I=1 & I =0 Swanson PLB 598, 197 (2004) Tornqvist PLB 590, 209 (2004) Swanson PLB 588, 189 (2004)
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X(3872) conclusion Not a cc state Matches all(?) expectations for a D 0 D* 0 bound state CC u c u c 1 st clear example of a non-qq meson
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Are there others? Is the X(3872) a one-of-a-kind curiousity? or the 1 st entry in a new spectroscopy? Look at other B decays hadrons+J/ B K J/ B K J/ B K J/
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B K J/ in Belle “Y(3940)” M≈3940 ± 11 MeV ≈ 92 ± 24 MeV M bc S.K. Choi et al hep-ex/0408126 PRL
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Y(3940): What is it? Charmonium? –Conventional wisdom: J/ should not be a discovery mode for a cc state with mass above DD & DD* threshold! Some kind of -J/ threshold interaction? –the J/ is not surrounded by brown muck; can it act like an ordinary hadron? J/
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Y(3940): What is it (cont’d) ? another tetraquark? –M ≈ 2m Ds –not seen in Y J/ ( contains ss) –width too large?? –need to search for Y(3949) D S D S s c s c ?? PRL 93, 041801 M( J/ )
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Y(3940): What is it (cont’d) ? cc-gluon hybrid? –predicted by QCD, –decays to DD and DD* are suppressed –large hadron+J/ widths are predicted –masses expected to be 4.3 ~ 4.4 GeV (higher than what we see) cc Horn & Mandula PRD 17 898 (1974)
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Summary X(3872): –J PC established as 1 ++ –cc component is small (≤ few %) –all properties consistent with a D 0 D* 0 bound state uc u c 1 st unambiguous example of a non-standard meson Y(3940): –No obvious cc assignment –tetraquark seems unlikely –cc-gluon hybrid? cc ????? - Lots to do: determine J PC ; find other modes (DD*, D s D s, …?)
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Mahalo
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Back-up slides
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Difference between QED & QCD QED: photons have no charge QCD: gluons carry color charges gluons interact with each other
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Vacuum polarization QED vs QCD 2n f 11C A in QCD: C A =3, & this dominates
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QED QCD difference Coupling strength distance
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Testing the Standard Model QCD X Electro-Weak X QED decrease in s with distance Lamb-shift g-2 Atomic spectra … W, Z & t masses Z width sin W Asymmetries Cross-sections …
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Tests of QED and EW sectors Electro-Weak sector (tested @ ~0.01% level) QED (tested @ ppb) Example: (g-2)/2| electron Expt: 1,159,652,188.4(4.3)x10 -12 Theory: 1,159,652,201.4(28)x10 -12
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M( J/ ) look-back plot
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Another one? e + e - J/ + X >4 )peak at M=3940 11 MeV N=148 33 evts Width consistent w/ resolution (= 32 MeV) cc cc c0 cc ‘ ‘ What is it? c0 ? c ?? ‘“
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Look at e + e - J/ D(D ( * ) ) Reconstruct a J/ & a D use D 0 K - + & D + K - + + Determine recoil mass
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Look at M(DD ( * ) ) DD* DD 3940 MeV 9.9 ± 3.3 evts (4.5 ) 4.1 ± 2.2 evts (2.1 ) c0 DD* ‘ c DD “
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Other hadronium states? M=1859 MeV/c 2 < 30 MeV/c 2 (90% CL) J/ pp in the BES expt M(pp)-2m p (GeV) 00.10.20.3 acceptance 2 /dof=56/56 fitted peak location +3 +5 10 25 J.Z.Bai PRL 91,022001(2003)
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