Alexis POMPILI ( University & I.N.F.N. of Bari ) [ Collaboration]

Alexis POMPILI (University & I.N.F.N. of Bari)

[ Collaboration]

Results from BABAR , CLEO & Belle

QCD@Work 2003 Conversano - 15 June 03

Observation of two narrow mesonsin the and final states

0sD 0sD

QCD @ Work 2003 A.Pompili (U. of Bari &

I.N.F.N.)

2

Outline

spectroscopy before new states observationsc

Charm physics @ B-factories – reconstruction method issues

Summary and conclusions

Observation of the first new state - features

Evidence for a second new state - features

Feedback/explanations by theorists

QCD @ Work 2003 A.Pompili (U. of Bari &

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3

Spectroscopy of statessc

S. Godfrey and N. Isgur, Phys. Rev. D32, 189 (1985); S. Godfrey and R. Kokoski, Phys. Rev. D43, 1679 (1991), M. Di Pierro and E. Eichten, Phys. Rev. D64, 114004 (2001)

Potential models of [heavy-quark | light-quark] mesons have had so far reasonable success in describing the spectroscopy of the D, Ds, B, Bs systems

Godfrey-Isgur model

P-waveS-wave

Limited experimen

tal informatio

n

)2573(*sJD

)2535(1sD

)2112(*sD

)1969(sD

(mix?)

%)6(%),94( 0

131 S

011 S

132 S

012 S

?

?

??

231 P

)48.2(1 03P

131 P

)53.2(1 11P

isospin-violating

[narrow]

[narrow]

lightheavy SLjSjJ

,

doublet23j

Predicted mass range:

Predicted large width range :(for decay by K-emission)

doublet21j

26.24.2 cGeV

MeV990270

NO experim. candidates (so far)

IF their masses were below D(*)K threshold, they would decay byisospin-violating -emission andwould be extremely narrow !

The results presented here concern 2 states [0+,1+], below DK, D*K threshold, decaying to Ds0, Ds*0 !

QCD @ Work 2003 A.Pompili (U. of Bari &

I.N.F.N.)

4

Charm Physics @ B-factories

The Y(4S) resonance “lays” on a large continuum bkgd :

e+e- colliders @ Y(4S) Beams Data taking Det./Expt. [*]

CESR (Cornell) Symmetric 1990-1999 CLEO-II

PEP-II (SLAC) Asymmetric Start: 1999

KEK-B (Tsukuba) Asymmetric Start: 1999 Belle[*] Integrated Luminosity relative to the data sample used for the results presented here

Ldt

19.86 fb

15.91 fb

15.13 fb

Powerful tool for charm physics

e+e- (nb) bb cc ss uu dd

1.05 1.30 0.35 1.39 0.35

+- +- e+e-

0.94 1.16 40

Effective cross sections at the energy of the Y(4S)

QCD @ Work 2003 A.Pompili (U. of Bari &

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5

Charm Physics from Continuum Production

By using inclusive continuum events … combinatorial bkg is strongly reduced !

Kinematical selection: require cut on CMS momentum of charmed meson :

SD

D

Solid (open) points: on (off) resonance data [normalized]

cGeVpD 5.2*

It can be increased for cleaner samples (if statistics allows)

QCD @ Work 2003 A.Pompili (U. of Bari &

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6

Reconstruction Method & Selection Criteria (from )

000 ;,; KKKKDD ss

PID MeVE 100

geometric fit at a common vertex :

not sharing photons

with others

NOT IN SCALE

consistent with productionat the interaction region

%1.0)( 2 P

cGeVp 5.2*

couples (origin in production vertex) with kinematic fit [constraint : m(0)] : %1)( 2 P

couples (origin in track vertex) with kinematic fit [constraint : m(0)] : %10)( 2 P

[charge-conjugate configurations are implied]

(or tighter)

QCD @ Work 2003 A.Pompili (U. of Bari &

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Further background rejection

Select quasi-two body decay modes

Helicity angles cut [ 2-body decays of ]

],[ 0* KK

),( 0*K

D

sD

5.0cos

2 disjointsub-samples

QCD @ Work 2003 A.Pompili (U. of Bari &

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sDKKKK ,,, 0Mass Spectra :

0 : kinematic fit E(Ds+): Ds

+ mass constraint

Broad peak due to random

combination

where

candidateswitheventsincouples 0 sD

)2112(*sD ss DD )2112(*

0)2112(* ss DD

No other signal is evident up to 2.7 GeV/c2 a part

that

associated with

!!A signal @ 2.32 GeV/c2 is

missing in sidebands dist’ns :

the peak is associated to the

Ds+ 0 system !

Ds+0 mass spectra and fits [ hep-ex/0304021, 12 April @ PRL]

0 KKDs

KKDs

cMeVp 300)( 0

cGeVp 5.3*

2.)(4.08.2316 cMeVstatm 2.)(4.06.8 cMeVstat

2.)(3.16.2317 cMeVstatm 2.)(1.18.8 cMeVstat

Mass systematic uncertainty estimated conservatively to be < 3 MeV/c2

An estimate of the mass resolution for the system

K+K-+0 can be provided directly from the data

by fitting the mass dist’n for

characterized by a width consistent with that of

the observed signal .

A similar mass resolution can be obtained from

the simulation of

0 KKDs

0]0[)2317(* ssJ DD

)2317(*sJD

Observed width consistent with expt. resolutionIntrinsic width is smaller (<10MeV/c2)[I-violation]

candidates531267

candidates33273

QCD @ Work 2003 A.Pompili (U. of Bari &

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QCD @ Work 2003 A.Pompili (U. of Bari &

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Decay Angular Dist’n)2317(*sJD

Angular dist’n consistent with being flat ( 43% probability )

w.r.tframerest in the angle: 00 sD

CMSin thedirection flight )2317(the * sJD

cosofbinswithin)2317(* sJD

[BKG subtracted]

arb

. u

nitEfficiency

arb

. u

nit

This would be expected for: a spin J=0 state a higher-spin state produced unpolarized

QCD @ Work 2003 A.Pompili (U. of Bari &

I.N.F.N.)

11

Tests for Reflections

ccee )2317(*sJDNO signal found using simulation of all known charmed states and decays

NO signal found when exchanging -K identification hypotheses [no D+,D0,D* seen])2317(*sJD

Investigated decays involving known particles and generating a signal through the addition/omission/substitution of a or a . Nothing found ! However...

)2317(*sJD

][)( 20 cGeVDm s

evt

s/7

MeV

/c2 )2317(*

sJDcGeVDp s 5.3)( 0*

? Combinations

Combinations

0sD

0*

sD

Is this peak @ 2.46GeV/c2 a new narrow state kinematicallyfeeding-down a signal:

)2317(*sJD

0* sD

recoil)2460( XXee

sD lost/random

)2317(*sJD

CHECK [MC UNFOLDING] : this feed down … …1) would have a width =15MeV/c2 (smeared peak!)…2) can explain only 1/6 of the observed peak @ 2.32 GeV/c2

?

This possible signal requiresadditional detailed study

QCD @ Work 2003 A.Pompili (U. of Bari &

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Confirmation of @ CLEO II & Belle)2317(*sJD

[@ CIPANP/03 – 20 May]

30231

43770

)( 0SDm

)()( 0 SS DmDm

Ds sidebands0 sidebands

SDonly

2.)(5.02.2317 cMeVstatm 2.)(0.13.350 cMeVstatm 2.)(5.01.8 cMeVstat2.)(4.8 4.1

2.1 cMeVstat

Consistent with experimental resolution

[ hep-ex/0305017 ]

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Jp =? & Other Decay Modes)2317(*sJD

cGeVDp s 5.3)(*

cGeVDp s 5.3)(*

][ 2cGeVm

)2112(*sD

Studied decay modes into:

sD

*

sD

][];[,,, CLEOCLEO&00* sssss DDDDD ARABB

NO significant signals seen within current statistics

Combinations

Combinations

Combinations

sD

CLEO B.R. [w.r.t Ds+0]

Upper Limits

MODE 90%C.L .

< 0.054

< 0.078

< 0.020

sD*

sD sD

For a parity conserving decay to Ds+[0-]0, only natural spin-parity series is allowed: Jp = 0+,1-,2+,…

IF Jp = 0+ (suggested by low mass & compatible with helicity dist’n)… … it cannot decay into Ds

+[0-]… whereas… e.-m. decay into Ds*+[1-] is allowed (by parity & angular momentum conservation)

On the other hand, IF Jp = 1+, it could strongly decay into Ds++- [I-conserving, OZI-suppressed]

IF Jp = 0+, it cannot (0+ 3pseudoscalars)!

QCD @ Work 2003 A.Pompili (U. of Bari &

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“Theorists sent back to their drawing boards” [from: SLAC Press Release]

10 papers in May 1-20 ! 2 main classes of interpretations :

a) Within a quark model representation

b) quark model explanations unlikely: different type of state (tetraquark)

]state a still (2317)[ * scDsJ

],)([ , dunnnsc

Cahn & Jackson hep-ph/0305012 Modified potential model in standard spectroscopy

van Beveren & Rupp hep-ph/0305035 Quasi-bound in unitarized meson model

Bardeen, Eichten & Hill hep-ph/0305049 Chiral Perturbation theory + HQET

Godfrey hep-ph/0305122 Revision needed for masses! Crucial is the B.R. for decay

Colangelo & De Fazio hep-ph/0305140 Heavy quark spin-flavor sym.+ Vector Meson Dom. Ansatz

sc

sc

Barnes,Close & Lipkin hep-ph/0305025 molecular type 4-quark state [DK molecule]

Cheng & Hou hep-ph/0305038 4-quark state

Szczepaniak hep-ph/0305060 D atom

Bali hep-ph/0305209 Lattice predictions on masses consistent with quark modelsc

*sD

QCD @ Work 2003 A.Pompili (U. of Bari &

I.N.F.N.)

15

: is it really a new state?

)2317(*sJD

0)2460( sDX

MC studies : including ccee

0

*

random

ss DD

Kinematical CROSS-THROUGH

random

0* )2317(

ssJ DD

random

0* )2317(

ssJ DD

0

*

random

ss DD

Concern: FEED-UP from : for signal band there is a … … peaking BKG associated with the crossing band produced by

)2317(*sJD

ss DD*

0* )2317( ssJ DD

This can be addressed with different techniques! For istance: a) MC-based unfolding method: feed-up probability & lineshape distortion [CLEO] b) Sidebands from data used to estimate peaking BKG [CLEO & BELLE]

will releaseresults soon

)( 0sDm

)( 0SDm)( 0SDm

)( sDm

QCD @ Work 2003 A.Pompili (U. of Bari &

I.N.F.N.)

16

… YES! Evidence of a new state @ 2.46 GeV/c2 into 0* sD

Ds*(2463) Ds* 0 Sideband

subtractionUnfolding

method

Number of candidates 40.8 ±11.3 40.7 ± 10.6

M(Ds*0) M(Ds*) [MeV] 351.6 ±1.7 350.6 ± 1.2

[MeV] 5.3 ± 1.2 6.1 ± 1.0

CLEO

Statistical significance ~ 5.3

BELLE

Ds* signal region

Ds* sidebands region

Upper Ds* sidebandLower Ds* sideband

Ds* signal region Ds* signal region

)2460(*sJD

Statistical significance ~ 4.2

Peaking BKG : 38±8 candidates

BKG-subtracted yield: 93±22 cand.

Raw yield :131±21 candidates

[@ CIPANP/03 – 20 May]

2.)(4.10.2459 cMeVstatm 27 cMeV 27 cMeV

Feed-up:9%

)( 0SDm

QCD @ Work 2003 A.Pompili (U. of Bari &

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states in exclusive decays of B mesons [byBELLE]

MODE 90%C.L .

< 0.49

< 0.16

< 0.08

sD*

sD sD

*sJD

(@ FPCP/03 – 5 June)

A preliminary helicity dist’n shows to be consistent with 1+ state

CLEO B.R. [w.r.t Ds*+0]

Upper Limits

Dominant exclusive process for the two DsJ* production in B decays is : *sJDDB

0)2460(* PSsJ JDD

03.007.021.0))2460((

))2460((0**

*

SsJ

SsJ

DDB

DDB

13fb -1

90fb -1

0*SDD sDD

QCD @ Work 2003 A.Pompili (U. of Bari &

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18

Summary & Conclusions

Most results are compatible with models based on HQET and chiral symmetry, which predict that 0+ & 1+ are the chiral partners of the 0- & 1- states, with same mass splitting.

Interesting times ahead both for experimentalists & theorists.

Two narrow states have been observed, in the inclusive Ds0 & Ds*0 invariant mass distributions, near 2.317GeV/c2 & 2.460GeV/c2. The widths [<10MeV/c2] are consistent with experimental resolution. The smaller intrinsic widths are due to isospin-violation in their decay. The most likely assignment for their spin-parity is 0+ & 1+.

The mass splittings m[DsJ*(2317)]-m[Ds(1969)] & m[DsJ*(2460)]-m[Ds*(2112)] are consi-stent with being equal as predicted by Bardeen et al. (BEH) if these are 0+ & 1+ states.

They do not fit well into the existing potential models for spectroscopy.sc

The B.R. Upper Limit for the decay of Ds*(2317) into Ds*, Ds and Ds+- [w.r.t. Ds0] and the preliminary B.R. measurement for the decay of Ds*(2460) into Ds [w.r.t. Ds*0] are consistent with BEH predictions.

QCD @ Work 2003 A.Pompili (U. of Bari &

I.N.F.N.)

?

Few more numbers…

MODE 90%C.L .

< 0.054

< 0.078

< 0.020

MODE 90%C.L .

< 0.49 /

< 0.16

< 0.08

03.007.021.0 ))2460((

))2460((0**

* modefinal

SsJ

sJ

DDB

DB

))2317((

))2317((0*

* modefinal

SsJ

sJ

DDB

DB

sD

*sD

sD

sD

sD*

sD

CLEO

BELLE

BEH

0

0.08

0

BEH

0.24

0.22

0.20