P.Pakhlov ITEP, Moscow (for Belle collaboration) e+e- collision from to Novosibirsk, BINP, 2006.

Double charmonium Double charmonium production in eproduction in e++ee--

annihilationannihilationP.PakhlovP.Pakhlov

ITEP, Moscow ITEP, Moscow

(for Belle collaboration)(for Belle collaboration)

e+e- collision from e+e- collision from to to Novosibirsk, BINP, 2006Novosibirsk, BINP, 2006

Novosibirsk’06, Novosibirsk’06, P.PakhlovP.Pakhlov

Theory introductionTheory introductionLast 30 years NRQCD serves to Last 30 years NRQCD serves to calculate charmonium calculate charmonium production: production:

factorization perturbative (cc factorization perturbative (cc production) and non-perturbative production) and non-perturbative (cc hadronization into charmonium) (cc hadronization into charmonium)

= = nn(cc) (cc) OOnnccccColor Singlet ModelColor Singlet Model (ignore (ignore (cc)(cc)88) was ok before Tevatron ) was ok before Tevatron ’ ’ surplus problem appears (1994)surplus problem appears (1994)Color Octet ModelColor Octet Model was believed was believed can solve the Tevatron problemcan solve the Tevatron problem

Purely phenomenologic approach: Purely phenomenologic approach: free parameters -- free parameters -- OOnncccc,, to tune to to tune to the datathe dataIf tune parameters to the observed If tune parameters to the observed pp(((2S)) spectra, still have (2S)) spectra, still have problem to predict polarizationproblem to predict polarization


Charmonium production Charmonium production in ein e++ee--

Big surprise #1Big surprise #1

1990 CLEO:1990 CLEO: e e++ee- - J/J/ X X exists!exists!15.2 15.2 4.6 J/ 4.6 J/ events events above kinematical limit above kinematical limit for B-decays (p>2.0 for B-decays (p>2.0 GeV/c) in GeV/c) in (4S) data(4S) data

((ee++ee- - J/J/ X )~2 pb X )~2 pb

Was not predicted by Was not predicted by theory, but first theory, but first observed experimentallyobserved experimentally

LL~1fb~1fb--

11


Theory: production in eTheory: production in e++ee--

Color-SingletColor-Singlet e e++ee- - J/J/ cc was cc was estimated to be very small by estimated to be very small by Kiselev et al.Kiselev et al. (1994)(1994)

~0.05 pb ~0.05 pb should be unobservable should be unobservable even at high luminosity B-factorieseven at high luminosity B-factories

Color-octetColor-octet ee++ee- - ( (cc)cc)88 g g J/J/ g g (with (with OOnncccc fixed to Tevatron and fixed to Tevatron and others data) should not be large as others data) should not be large as well (but can be significant around well (but can be significant around the end-point of J/the end-point of J/ momentum) momentum) Braaten-Chen (1996)Braaten-Chen (1996)

Color-Singlet Color-Singlet ee++ee- - J/J/ gg is the gg is the best candidate! Predicted best candidate! Predicted CSCS~1-2 ~1-2 pb pb Cho-Leibovich (1996)Cho-Leibovich (1996)


Belle’s first resultBelle’s first resultIdea is to study the recoil mass against Idea is to study the recoil mass against reconstructed J/reconstructed J/ using two body kinematics using two body kinematics (with a known initial energy)(with a known initial energy)

MMrecoilrecoil = = (E(Ecmscms- E - E J/J/ ) )22 - P - P J/J/ 22 ) )

2002, Belle found large cross-sections for: 2002, Belle found large cross-sections for: ee++ee- - J/J/ cc

ee++ee-- J/J/ c0c0

ee++ee-- J/J/ cc‘‘

LL~45fb~45fb--

11


Belle’s first resultBelle’s first resultNot the whole story!Not the whole story!

In addition, also observed In addition, also observed associated production associated production

ee++ee-- J/J/ D D(*+)(*+) X X

ee++ee-- J/J/ D D00 X X

Immediately demonstrates Immediately demonstrates large large ee++ee- - J/J/ cc unlike cc unlike theory predictiontheory prediction

Based on LUND ccBased on LUND cc DD*+*+/D/D00 fragmentation rates fragmentation rates calculated:calculated:(e(e++ee--→→ J/ J/cc)/cc)/(e(e++ee--→→

J/J/X) =0.59X) =0.590.140.140.120.12


Using more dataUsing more data

Belle 2004: Full Belle 2004: Full analysis of double analysis of double charmonium charmonium productionproduction

Reconstructed Reconstructed charmonium:charmonium:

J/J/(2S)(2S)

Recoil charmonium:Recoil charmonium:All known charmonium All known charmonium states below DD states below DD thresholdthreshold

LL~155f~155fbb-1-1


Cross-sectionsCross-sections

Interesting: Interesting: Orbital excitations are not suppressed!Orbital excitations are not suppressed!

Only S,P states are seen recoiling to V charmonium!Only S,P states are seen recoiling to V charmonium!

cc J/J/ c0c0 c1c1++c2c2 cc(2S)(2S) (2S)(2S)J/J/(2S)(2S)

25.625.62.82.833.4 .4

16.316.34.64.633.9.9

<9.1 <9.1

<16.9<16.96.46.41.71.71.1.

0 0 12.512.53.83.8

3.13.1

<5.3<5.3

<8.6<8.616.516.51.71.7

0.4 0.4

16.316.34.64.63.93.9

<9.1 <9.1

<16.<16.99

Born cross-sections: * BR (recoil charmonium >2charged)

Reco

nst

ruct

ed R e c o i l


Can theory adopt this Can theory adopt this resultresult

The first NRQCD estimates: The first NRQCD estimates: R=R=J/J/cc

//~~ss22(m(mccv/Ev/Ebeambeam))6 6

(e(e++ee--→→J/J/cc)=2.3)=2.31.1 fb ~10 times 1.1 fb ~10 times lower!lower!

matrix elements are fixed from matrix elements are fixed from annihilation constants using J/annihilation constants using J/→ → ee++ee--, , cc

Bodwin-Braaten-Lee 2003Bodwin-Braaten-Lee 2003; confirmed ; confirmed by by Liu-He-ChaoLiu-He-Chao, , Brodsky-Ji-LeeBrodsky-Ji-Lee

Double photon annihilation also can Double photon annihilation also can not resolve the disagreement: not resolve the disagreement:

experimentally eexperimentally e++ee--→ → J/J/ J/ J/ is not seen; is not seen;

theoretically (after correcting mistake) theoretically (after correcting mistake) ee++ee--→ → → → J/J/ cc is small. cc is small.


BaBar’s confirmationBaBar’s confirmation2005, BaBar2005, BaBar also see also see double charmonium double charmonium events events

ee++ee- - J/J/ cc

ee++ee-- J/J/ c0c0

ee++ee-- J/J/ cc‘‘


New ideasNew ideasWe need to solve an order of magnitude disagreementWe need to solve an order of magnitude disagreement

Kaydalov 2003.Kaydalov 2003. NRQCD is wrong! Use instead Redge NRQCD is wrong! Use instead Redge trajectories approach – tune free parameters from D meson trajectories approach – tune free parameters from D meson production production get reasonable agreement for e get reasonable agreement for e++ee--→→ J/ J/cc (cc (~1 ~1 pb) and pb) and predict predict ~10%~10% of J/of J/cc are double charmonium (Mcc are double charmonium (Mcccc <2M<2MDD))

Bondar Chernyak 2005. Bondar Chernyak 2005. Try to save NRQCD! Light cone Try to save NRQCD! Light cone expansion formalizm. Use wider wave functions. Manage to expansion formalizm. Use wider wave functions. Manage to “predict” “predict” (e (e++ee- - J/J/ cc )~30 fb )~30 fb

Braguta Likhoded Luchinsky 2006Braguta Likhoded Luchinsky 2006. Similar approach to . Similar approach to BC BC applied for all final states: reasonable agreementapplied for all final states: reasonable agreement

All approaches are phenomenological. Need to predict All approaches are phenomenological. Need to predict something that can be checked.something that can be checked.

3

1M

s


Angular analysisAngular analysisFit MFit Mrecoilrecoil(J/(J/) in bins of ) in bins of J/J/ production and production and helicity angleshelicity anglesCorrect on efficiencyCorrect on efficiencyFit with ~(1+Fit with ~(1+coscos22))

production and helicity production and helicity angles separatelyangles separatelysimulteneously: simulteneously: prodprod==helhel

prodprod helhel prodprod==helhelLLminmin NRQCNRQC

DDgluebglueb

allallcc

c0c0

cc’’

+1.4+1.4+1.1+1.1--

0.80.8

-1.7-1.70.50.5

+1.9+1.9+2.0+2.0--

1.21.2

+0.5+0.5+07+07--

0.50.5

-0.5-0.5+0.7+0.7--

0.50.5

+0.3+0.3+1.0+1.0--

0.70.7

+0.93+0.93+0.87+0.87-0.47-0.47

+0.87+0.87+0.86+0.86-0.63-0.63

+1.0+1.0

-1.0-1.0

+1.0+1.0

+1.0+1.0

+0.25+0.25

+1.0+1.0

-1.0-1.0

-1.0-1.0

-1.0-1.0

-1.01-1.01+0.38+0.38-0.33-0.33


Angular analysisAngular analysis

Measure: L=1 for Measure: L=1 for J/J/ c c and and J/J/ cc‘ as ‘ as expected expected

L=0 is measured for J/L=0 is measured for J/ c0 c0 ; NRQCD ; NRQCD expects L=0,2 with similar fractions expects L=0,2 with similar fractions ((c0 c0 is a P-wave)is a P-wave)

Can be used to check BC & BLL Can be used to check BC & BLL models. We pay their attention to this models. We pay their attention to this measurement measurement


New stateNew state Add more data and Add more data and

extend searching region extend searching region above DD thresholdabove DD threshold New peak at M~3.9 New peak at M~3.9

GeV, Temporary called GeV, Temporary called X(3940)X(3940) Two peaks are not Two peaks are not

excluded, but the excluded, but the second is not significant second is not significant with the present with the present statisticsstatistics Significance 5.0 Significance 5.0 =39 =39 26 MeV 26 MeV

(< 93MeV @ (< 93MeV @ 90%C.L.)90%C.L.)

LL~450f~450fbb-1-1


X(3940) decaysX(3940) decays

Expect XExpect XDD or DD or DDDD**

Try to find these Try to find these decays: decays:

Reconstruct J/Reconstruct J/ & & two D’s – no chancetwo D’s – no chance

J/J/ & one D & see & one D & see the unreconstructed the unreconstructed D in MD in Mrecoilrecoil(D J/(D J/) -- ) -- challengingchallenging

D and DD and D** are well are well separated ~2.5separated ~2.5

Clearly seen in the dataClearly seen in the data


X(3940) X(3940) DD DD(*)(*)

X (3940)X (3940)DDDD**:: Clear peakClear peak N=24.5 N=24.5 6.9 (5.06.9 (5.0)) =15.1=15.110.1 MeV10.1 MeV M=3.943M=3.9430.006 GeV0.006 GeV

B B (X(3940)(X(3940)DDDD**)=(96)=(96+45+45--

3232±22)%±22)%

X(3940)X(3940)DD: no signalDD: no signal

N = 0.2N = 0.2+ 4.4+ 4.4-3.5 -3.5 < 8.1< 8.1

B B (X(3940)(X(3940)DD)<41%@ DD)<41%@ 90 C.L.90 C.L.


SummarySummary

Double charmonium production is Double charmonium production is interesting and still not completely interesting and still not completely understood phenomenaunderstood phenomena

Belle luminosity & theory’s wisdom Belle luminosity & theory’s wisdom grow! grow!

Hope to have more interesting results Hope to have more interesting results soon. soon.

P.Pakhlov ITEP, Moscow (for Belle collaboration) e+e- collision from to Novosibirsk, BINP, 2006.

Documents

Transcript of P.Pakhlov ITEP, Moscow (for Belle collaboration) e+e- collision from to Novosibirsk, BINP, 2006.