Charmonia above open charm threshold

Charmonia above open Charmonia above open charm thresholdcharm threshold

Yu.S.KalashnikovaYu.S.Kalashnikova

ITEPITEP

2

Charmonium Charmonium

4

3S

SS SO TV r V V Vr

2

2 cc

pH m V

m

Yu.S.Kalashnikova, ITEP

mmcc = 1.5 GeV = 1.5 GeV

3

3000

3250

3500

3750

4000

4250

0-+ 1-- 0++ 1++ 2++ 1+- 2-- 3-- 2-+

M, MeV

Theory: Godfrey-IsgurTheory: Godfrey-Isgur

DD

? ?


Expected Expected

Yu.S.Kalashnikova, ITEP 4

All eight cAll eight ccc states below D states below DDD threshold are threshold arewell-established, and properties are compatiblewell-established, and properties are compatiblewith quark modelwith quark model

New states above DNew states above DDD threshold do not fit threshold do not fit quark-antiquark assignementquark-antiquark assignement

New degress of freedom enter the gameNew degress of freedom enter the game

New charmoniaNew charmonia


ExperimentExperiment StateState Production Production mechanismmechanism

Belle, BaBar, CDF, D0Belle, BaBar, CDF, D0 X(3872)X(3872) B -> K decay, pB -> K decay, ppp

BelleBelle Z(3930)Z(3930)

Belle, BaBarBelle, BaBar Y(3940)Y(3940) B -> K decayB -> K decay

BelleBelle X(3940)X(3940) double charmoniumdouble charmonium

BelleBelle Y(4008)Y(4008) B -> K decayB -> K decay

BelleBelle Y(4160)Y(4160) double charmoniumdouble charmonium

BaBar, BESBaBar, BES Y(4175)Y(4175) ISRISR

BaBar, CLEO, BelleBaBar, CLEO, Belle Y(4260)Y(4260) ISRISR

BaBar, BelleBaBar, Belle Y(4350)Y(4350) ISRISR

BelleBelle Y(4620)Y(4620) ISRISR

BelleBelle Z(4430)Z(4430) B -> K decayB -> K decay



Warning:Warning:


Most of the new states are found only at Most of the new states are found only at B-factoriesB-factories

The number of events is tinyThe number of events is tiny

Not all the states seen at Belle are confirmedNot all the states seen at Belle are confirmed by BaBar, and by BaBar, and vise versavise versa


Hybrid excitationsHybrid excitations

DDDD loops and threshold loops and threshold effectseffects

PionsPions

Degrees of frreedom which are frozen in Degrees of frreedom which are frozen in quark models start to reveal themselvesquark models start to reveal themselves

I. HYBRIDSI. HYBRIDS


Hybrid excitations:Hybrid excitations:gluon with two “minimal” gluon with two “minimal” strings attachedstrings attached q

qg


Y(4260): hybrid Y(4260): hybrid charmonium?charmonium?


BaBarBaBarBelleBelle


Y(4320): Y(4320): hybridhybrid charmonium? charmonium?

Charmonium hybridsCharmonium hybrids(mass, MeV)(mass, MeV)


JJPCPC QCD QCD string string

LatticeLattice

00-+-+ 42504250 11-+-+ 43204320 43004300 11---- 44004400 44004400 22-+-+ 44504450

QCD string: Yu.S.K., A.NefedievQCD string: Yu.S.K., A.NefedievLattice: J.Dudek Lattice: J.Dudek et alet al

Exotics!Exotics!

Selection rule:Selection rule:


hhmagnetimagneti

cc

DD(*)(*)DD(*)(*)

DD(*)(*)DDJJ(*)(*)

Y(4260) and Y(4320) as Y(4260) and Y(4320) as hybrids:hybrids:


Observed in ISR, so they are vectorsObserved in ISR, so they are vectors

ee++ee-- width is small width is small

reside in a dip in Rreside in a dip in R

do not couple to Ddo not couple to D(*)(*)DD(*)(*)

hybrids?hybrids?

LGT: (1LGT: (1----))hh @ 4400 MeV @ 4400 MeV

SScccc = 0 for (1 = 0 for (1----))hh -> spin flip is needed -> spin flip is needed for J/for J/ mode mode

Problems:Problems:

II. LOOPSII. LOOPS


16

DD loops:DD loops:(unquenching quark model)(unquenching quark model)

D

D

D

D

cc

=

+cc

D

D

D

D

DD

D

DD

D


17

Coupled channels

0

2 3

2

( ) ( )( , , )

( )

( )( ) ( ), ( )

/ 2 0

i i k kik i k

ii i

i i i

f p f pt p p M

M M g M

f p d pg M g M g M

p E i

1 2( ) ( )ii

c M i M i

cc DD

Interaction: f(p)= p

One bare cc statewith the mass M0

Hadronic Hadronic shiftshift


Quark models provide a good fit toQuark models provide a good fit tolowest charmonia levels and 1D, 3S, 4Slowest charmonia levels and 1D, 3S, 4Sexcitationsexcitations

With loops included, in explicit calculations With loops included, in explicit calculations one finds large hadronic shiftsone finds large hadronic shifts(about 200 MeV from the lowest set of (about 200 MeV from the lowest set of thresholds only)thresholds only)

Does unquenching destroy Does unquenching destroy naïve quark model?naïve quark model?


Sum rules:Sum rules:(exact in nonrelativistic limit)(exact in nonrelativistic limit)

Hadronic shifts are the same Hadronic shifts are the same for a given multipletfor a given multiplet

There is no JLS There is no JLS JL’S’ mixing JL’S’ mixing via loopsvia loops

Loop effects are hidden?Loop effects are hidden?


Sum rules are severely violatedSum rules are severely violatedby S-wave thresholds strongly by S-wave thresholds strongly coupled to the initial qcoupled to the initial qqq state: state:

Nonanalyticity of the DD scattering amplitude,Nonanalyticity of the DD scattering amplitude, and cusps in crossectionand cusps in crossection

Extra singularities (Extra singularities (CC polesCC poles))

genuine quarkonium survuves, but CC state disappearsgenuine quarkonium survuves, but CC state disappearsIn the NIn the Nc c limit limit

Weird charmoniaWeird charmoniaand relevant thresholdsand relevant thresholds


X(3872) D0D0* 3872 MeVD+D-* 3879 MeV

Y(4260) DD1 4285 MeV

Y(4325) D*D0 4360 MeV

(4430) D*D1 4430 MeV

Threshold affinity means that the admixture of D-meson pairs in the wavefunction could be large

X(3872) X(3872)

X(3872) 25 evt 3.5 σ

659 evt 11.6σ522 evt 5.2σ

MX = 3871.3 ±0.7 ± 0.4 MeV MJ/ψππ–MJ/ψ = 774.9 ±

MX = 3872.0 ±0.6 ± 0.5 MeV 3873.4 ±0.14 MeV

Br(B- → XK-)×Br(X→J/ψππ) = (1.3 ± 0.3) 10–5 (1.28± 0.41) 10–5

3871.77

MJ/ψππ– MJ/ψ

37 evt 10

22


M(D0D*0)=3871.81 M(D0D*0)=3871.81 0.36 MeV 0.36 MeVM(X)=3871.46 M(X)=3871.46 0.09 MeV 0.09 MeV

JJPCPC = 1 = 1++++


X(3872) as a X(3872) as a CCCC state: state:

bare bare c1c1(2(233PP11) charmonium state) charmonium stateattracted to D0D*0 S-wave thresholdattracted to D0D*0 S-wave threshold

Bugg, YuSK, Danilkin&SimonovBugg, YuSK, Danilkin&Simonov

Spectral density of the 2Spectral density of the 233PP11 charmoniumcharmonium

level in the clevel in the ccc-D-D(*)(*)DD(*)(*) coupling scheme coupling scheme


YuSKYuSK Danilkin&SimonovDanilkin&Simonov

Quark model for bare state + Quark model for bare state + 33PP00-type pair creation vertex-type pair creation vertex


Flattè analysis of Belle data on XFlattè analysis of Belle data on X

J/J/D0D0D0D000

Assumptions: Assumptions: Coupled-channel model for the XCoupled-channel model for the XConclusions: Conclusions: Belle data are compatible with thisBelle data are compatible with this assumptionassumption

YuSK&NefedievYuSK&Nefediev

III.OPE –BOUNDIII.OPE –BOUNDMOLECULESMOLECULES



Mesonic molecules bound by Mesonic molecules bound by one pion exchangeone pion exchange

One pion t-channel exchange in theOne pion t-channel exchange in theI=0 1I=0 1++++ D DDD* channel is attractive, so* channel is attractive, soa molecule can be formed, in perfect analogya molecule can be formed, in perfect analogywith deuteronwith deuteron

Voloshin@Okun, deRujula, Georgi&Glashow (circa 1976)Voloshin@Okun, deRujula, Georgi&Glashow (circa 1976)

Tornqvist, Swanson,…Tornqvist, Swanson,…

Star flipping:Star flipping:OPE in the 1OPE in the 1++++ DD* DD*


DD

D*D* DD

D*D*

X(3872) asX(3872) asDD* bound-DD* bound-statestate

Deeply bound molecular statesDeeply bound molecular states


DD* : generic vertex is D* -> DDD* : generic vertex is D* -> D in P-wave, in P-wave, molecule is loosely boundmolecule is loosely bound

DD(*)(*)DDJJ: generic vertex is D: generic vertex is DJJ -> D -> D(*)(*) in S-wave, in S-wave, molecule is deeply boundmolecule is deeply bound

Close Close et alet al

Y(4260) and Y(4320) Y(4260) and Y(4320) as 1S and 2S molecular states in the D*Das 1S and 2S molecular states in the D*D11

system bound by one pion exchangesystem bound by one pion exchange

However…However…


In existing molecular models pions are not treatedIn existing molecular models pions are not treateddynamically, but enter dynamically, but enter static static potentialpotential

Three-body cutsThree-body cuts are ignored are ignored

Inclusion of dynamical pions leads to imaginaryInclusion of dynamical pions leads to imaginarypart of the potential, and bound states cease to exist part of the potential, and bound states cease to exist

Baru Baru et alet al

IV. ZIV. Z++ss





Z-states are Z-states are chargedcharged, and, as such, are, and, as such, arenecessarily exoticnecessarily exotic

Z-states are seen Z-states are seen only only @ Belle@ Belle

If exist, could beIf exist, could be

compact tetraquarkscompact tetraquarks

moleculesmolecules

hadrocharmonia hadrocharmonia (whatever it means)(whatever it means)

ConclusionsConclusions


There is no theoretical concensus on the There is no theoretical concensus on the nature of new statesnature of new states

More high statistics and high resolution More high statistics and high resolution data is needed to confirm/rule outdata is needed to confirm/rule out different assignementsdifferent assignements

PANDA on the horizon:PANDA on the horizon:


High luminosity High luminosity O(10 O(1033) c) ccc pairs per day pairs per day

High beam momentum resolution High beam momentum resolution precise precise measurements of mass and widthmeasurements of mass and width

Detector Detector hadronic modes accessible hadronic modes accessible (DD(DD, DD, DD etc) etc)

pppp -> c -> cccpppp -> c -> ccc + light hadrons + light hadrons

Documents

Charmonia above open charm threshold