Results on Charmonium and Bottomonium Tom Browder University
Results on Charmonium and Bottomonium Tom Browder (University of Hawaii) Will cover results from BESII, CLEO(-c), Ba. Bar and Belle Apologies: Not an expert but a backup speaker. Can only cover a small subset of interesting results in the available time. Thanks: I have borrowed from talks by Pedlar, Shepard, Olsen, Muramatsu, Mussa, CZ Yuan, Skwarnicki. I have benefitted from correspondence with Soren Prell and others.
S. Olsen Charmonium mesons formed from c- and c-quarks c r c c-quarks are heavy: mc ~ 1. 5 Ge. V 2 mp _ velocities small: v/c~1/4 (for b b, v/c ~0. 1) non-relativistic QM applies What is V(r) ? ?
“Cornell” potential c r ~0. 1 fm c slope~1 Ge. V/fm “confining” large distance component V(r) G. S. Bali hep-ph/0010032 2 parameters: slope & intercept 1/r “coulombic” short distance component
Charmonium spectrum
1 -- Charmonium states e- y J/y y’ s(e+e- hadrons) y” “narrow” “wide” (G~300 Ke. V) (G~100 Ke. V) (G~25 Me. V) Y(4415) e+ Important BES contribution to R Y(4040) Y(4160) Directly accessible via e+e- annihilation D-meson + anti-D meson mass threshold y” DD decay channel is open G(DD) 25 Me. V
(3770), (4040), (4160), (4415) In 1998 and 1999, BES scanned 91 energy points between 2 and 5 Ge. V to determine R. Phys. Rev. Lett. 84, 594 (2000) and 88, 101802, (2002).
Results from the new R analysis (2007) hep-ex: 0705. 4500
Resonance parameters (PLB 660, 315 (2008))
Current J/ and (2 S) Samples (× 106) Note: B( ψ(2 S)-> + -J/ψ)~32% one can tag J/ψ events very cleanly and efficiently. BESII : J/ 2001 – 58 M; CLEO-c: (2 S) 2006 -27 M CLEO-c has Cs. I(Tl) crystals, BESII does not but BESIII will.
Inclusive photon signal for ψ’ γ ηc ar. Xiv: 08 05. 0252 B(ψ(2 S)->γ ηc (1 S)) = (4. 32+-0. 16+-0. 60)*10^-3 B(J/ ψ->γ ηc (1 S)) = (1. 98+-0. 09+-0. 30)% Renormalize ηc BF scale B(J/ ψ->γ ηc (1 S))/B( ψ(2 S)->γ ηc (1 S)) = 4. 59+-0. 23+-0. 64.
Signal for J/ψ γηc η Discrepancy between c properties (especially widths) in different processes is unresolved.
P-wave states Gamma energy spectrum from y’ g X decays accessible via E 1 transitions from y’ Gaiser et al (Crystal Ball) PRD 34 711 E 1 Transition Partial width G ” ke. V 23 S 1 (y’) 13 P 2 (cc 2) les 17 ts p i n c e in rem prc 1 23 S 1 (y’) 13 Pst 1 (c a)su 24 ke. V 1 ” e rom 3 ith m f 3 2 Sb 1 le(y’) 1 24 ke. V w P 0 (cc 0) t a n cul eeme l a C r 3 g. P (c ) 13 S (J/y) a 1 420 ke. V 2 c 2 1 ood 13 P 1 (cc 1) 13 S 1(J/y) 290 ke. V 13 P 0 (cc 0) 13 S 1(J/y) 120 ke. V
Hadronic transitions G(y’ + -J/y) 70 ke. V n ee w t be t en eory m + G(y” gre e J/y) ke. V th 50 155 & a 1 nt PRD 4 e” l “allowed” e b na urem Yan o s a as ang & e e r “ m. Ku G(y’ h. J/y) 5 ke. V “allowed” c. f allowed +0 h G(y’ 0 J/y) 0. 3 ke. V isospin violating
CLEO 2005 +2007 update 0 The hcand ηc(2 S) have been observed ψ hc 0γ ηc Belle 2002 Charmonium table below D Dbar threshold is complete
Recent results on non-exotic charmonia 21 S 0 (ηc(2 S)) found by Belle S. K. Choi et al PRL 89 102001 properties as expected 23 P 2 found by Belle hep-ex/0507033 properties as expected 11 P 1 (hc) found by CLEO hep-ex/0508037 properties as expected 13 D 1 g 13 P 1 g 11 P 0 seen by CLEO, Phys. Rev. D 74: 031106, 2006. G(meas) = 75 18 ke. V G(theor) ~59 -77 ke. V
The potential model for (ccbar) charmonium mesons is robust and reliable. The old “missing states” (hc and ηc(2 S)) have now been observed Declare victory May 1, 2003
Problems with strong decays of charmonium MARK-II Old unsolved mystery K*K ρπ X-H Mo et al, review in hep-ph/06011214 (>10 proposals) W. S Hou’s idea, glueball-J/ψ mixing, seems to be ruled out Rosner One possible explanation
’ Baryon Anti-baryon OK First measurements by BESI, remeasure BR with BESII data sample. ’ Ξ- Ξ+ ’ ΛΛ ΛΛ-bar pπ pπ+ ’ Σ 0 + pπ pπ ΣΣ-bar ΞΞ-bar p 2π-p 2π+ ’ pp-bar pp Consistent with “ 12% rule”.
Bottomonium Data Samples Belle 2. 9 fb-1 (2006) , 11 M Y(3 S) Ba. Bar, 30. 3 fb-1, ~120 M Y(3 S) ~14. 4 fb-1 on the Y(2 S)
Bottomonium: Some mysteries in strong decays “QCD Multipole Expansion” What is special about the case m-n > 1 ?
Most famous ancient mystery (1994 -2000)
Possible Theoretical Explanations: High statistics data and sophisticated analysis may provide some clues (CLEO)
The matrix element for Υ(m. S) Υ(n. S) The amplitudes A, B could be complex In the above, ε, ε’ are the polarization vectors of the Υ(n. S), Υ(m. S) q 1, q 2 are the pion 4 -vectors while E 1, E 2 are their energies in the Υ rest frames. q 2 is the invariant mass of the two pions
CLEO High Statistics Analysis of di-pion matrix element M , θX
CLEO High Statistics Analysis of di-pion matrix element A, B are complex. B was previously neglected C is consistent with zero (spin flip and breakdown of QCD multipole expansion not present). PRD 76, 072001 (2006)
Recent data for Υ(4 S) Υ(1 S, 2 S) + Belle data Non-B Bbar decay Ba. Bar data PRL 96 (2006) 232001 PRD 071103 (R) 2007
CLEO’s first evidence for (2 S) (1 S) η preliminary 4. 6σ One candidate is found, Expect this is 16% of the η mode
Ba. Bar discovers Υ(4 S) (1 S)η These are examples of non-B Bbar decays that have been observed by Ba. Bar and Belle. preliminary
Could related transitions provide a way to discover the elusive hb or ηb ? Two suggestions: (Voloshin, Mod. Phys. Lett. A 19, 2895 (2004)) (Godfrey, Rosner, PRD 66, 014012 (2002) like CLEO’s hc search )
Where is the ground state bottomonium ηb ? Tests theory and is the highest priority of the quarkonium working group (QWG) Direct M 1 transitions Which Upsilon(n. S) is best ? Inclusive or exclusive ? What are the hadronic modes of the ηb ?
Second mystery or big problem in the field: Where is the ηb, the ground state bottomonium state ?
Search for a Y(4260) analogue in the bottomonium sector Y(4260) → J/y + - Is there a corresponding bb state b → (1 S) + - ? “Searching for the bottom counterparts of X(3872) and Y(4260) via + -Υ(1 S)”, Wei-Shu Hou, PR D 74, 017504 (2006) → theory inspiration (experimental work by Kai-Feng Chen and Anatoly Sokolov) Resonant structure is rather complicated above BB threshold. E. g. Y(10860) is commonly assumed to be a radially excited 1 -- b b bound state a. k. a the Y(5 S), but we do not really know that. World wide Y(10860) data: Total cross-section Collected mainly for Bs physics, ≈105 Bs / fb 1985 CLEO 0. 1/fb 2003 CLEO III 0. 43/fb 2005 Belle 1. 9/fb 2006 Belle 21. 7/fb Use this data to measure + - Υ(1, 2, 3 S) production at the (10860)
Anomalous (1, 2, 3 S) + -, (1 S) K+K- cross sections at (5 S) 3. 2 s 14 s PRL 100, 112001, 21. 7 fb 1 Final state (3 S) (2 S) 20 s (1 S) 4. 9 s (2 S) Initial state Gtot Me. V G (1 S) + ke. V (10860) 0. 032 6 (3 S) (4 S) (1 S) (10860) decay or decay of new overlapping state Yb? 0. 020 (3 S) 20. 5 (2 S) 110 0. 9 1. 8 590 (10860) Energy scan (7. 9 / fb) around (10860) : compare (1 S) + - and total hadronic cross sections. Results will be ready soon.
What about the dipion mass distributions for the Y(10860) ? (the state formerly known as the “Υ(5 S)”) Phase space, Cahn-Brown model (B=0) There are hints of a low mass structure in a) and b) but statistics are low.
Bottomonium: New Physics Potential Suppose those precision electroweak fits are taken literally, MH~76± 30 Ge. V. Suppose n. MSSM is correct, then there is a H and another light Higgs particle a 1 (m(a 1) <m(b)). Can avoid LEP limits and still have MH~100 Ge. V. (R. Dermisek, J. Gunion, B. Mc. Elrath) The dominant decay mode might be: Difficult at a hadron collider. But could find the light Higgs (a 1) in bottomonium at B or Super B Factories.
Bottomonium: New Physics Potential (cont’d) One motivation for Ba. Bar’s 30 fb-1 Y(3 S) run.
Hunting dark matter or light Higgs in Υ(n. S) decays High precision check of lepton universality in dilepton decays Light Higgs signature Can also search for the HYPER-CP particle using decays to a μ+ μ-
Ba. Bar’s final run Kirkby Expect compelling results on bottomonium from Ba. Bar (and perhaps Belle) in the near future.
More New Results (but not enough time to cover)
New Measurements of Upsilon(3 S) Branching Fractions (CLEO)
New Measurements of Upsilon(3 S) Branching Fractions (CLEO)
It looks like there may be a bb version of the Y(4260) lurking around the (5 S) W. -S. Hou PRD 74, 017504 (2007) If there are bb versions of the XYZ’s, why not ss versions as well?
1 -- Ys states around 2 Ge. V? Y(2175) f 0(980)f from Ba. Bar (confirmed by BESII) e+e- g f 0(980)h @ Ecm ~10. 6 Ge. V confirmed by BESII M(f 0(980)f Ge. V M. Ablikim et al (BES) PRL 100, 102003 (2008)
Backup Slides
The new 2007 improved results Comparison of the updated R value and the old results in Phys. Rev. Lett. 88 (2002) 101802 preliminary Differences in R values are due to the updated resonant parameters and initial state radiative correction factor (1+ obs). hep-ex: 0705. 4500
’ Baryon antibaryon OK BESII – CLEOc comparison pp-bar ΛΛ-bar ΣΣ-bar ΞΞ-bar Consistent with SU(3) symmetry. Reduced Branching Ratios R = Br/(π p* /s½), p* is baryon momentum. R’s same under SU(3) symmetry. Phys. Lett. B 648, 149 (2007) BES
Belle: G( (5 S) (n. S)) is Huge!! (4 S) (1 S) + - data ossse & ction ) 8 tim es as many event s! 44± 8 evts “ (5 S)” (1 S) 23. 6 fb-1 from Belle 2 S 3 S 4 S Belle 0710. 2577 K. F. Chen et al (Belle) PRL 100, 112001 (2008) (2 weeks ago) 325± 20 evts! (1/20 (4 S) (1 S) times ~ 1 / 477 fb-1 from Belle 10 th the ctrhe
Partial Widths Assume “ (5 S)” = (5 S) N. B. Resonance cross section 0. 302 ± 0. 015 nb at 10. 87 Ge. V PRD 98, 052001 (2007) [Belle] PDG value taken for (n. S) properties >100 times bigger!! Cf (2 S) (1 S) + - ~ 6 ke. V (3 S) 0. 9 ke. V (4 S) 1. 8 ke. V
Where is the ground state bottomonium ηb ? Tests theory and is the highest priority of the quarkonium working group (QWG) Which Upsilon(n. S) is best ? Inclusive or exclusive ? What are the hadronic modes of the ηb ?
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