Physics with open charm mesons @

Andrey SokolovIKP I FZ Jülich

May 19, 2005 Andrey Sokolov 2

PANDA Physics program

Charmonium spectroscopy:– Precision M and Γ measurement, error

and qq – potential.– Open charm physics.

Search for the charmed hybrids, glueballs.Study of modifications of the meson.

properties in the nuclear medium.Hypernuclear physics.

May 19, 2005 Andrey Sokolov 3

The DS± spectrum |cs> +

c.c. was not expected to reveal any surprises, but ...

– Potential model– Old measurements– New observations(BaBar, CLEO-c, Belle)

Or these are molecules?

New observations

0 1 0 1 2 2

Ds

Ds*

DsJ*

(2317)

Ds1

m [G

eV/c

2 ]

D0K

D*K

DsJ

(2458)

Ds2*

JP

May 19, 2005 Andrey Sokolov 4

May 19, 2005 Andrey Sokolov 5

Depend on internal structure the width of DsJ* can be different:

→ Current limit 4.9 MeV→ -doubling 10 keV→ Phenomenological 130 keV→ DsK – molecules 200 keV

Threshold production of DsJ

*(2317)

D*sJ

10 5pp

10 3pp10 4p

p

keVMinv

20

keVMinv

200 MeVMinv

2

May 19, 2005 Andrey Sokolov 6

Charmonium Physics

DD

DD*

ψ(11D2) ψ(13D1)

ψ(13D3)

ψ(13D2)

ηc(21S0)

D*D*

ψ(23S1)

J/ψ(13S1)

ψ(33S1)

c2(13P2)

c0(13P0)

c1(13P1)h1c(11P1)

c0(23P0)c1(23P1)

c2(23P2)

h1c(21P1)

ηc(11S0)

ηc(31S0)

JP=0- 1- 1+ (0,1,2)+ 2- (1,2,3)-

Are ψ(4040) and ψ(4160) strong mixtures of the Ψ(3S) and hybrid charmonium states or ψ(4040) is D*D*-molecule?

2.9

Mcc

[G

eV

/c2]

3.0

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

4.0

4.1

4.2

4.3

4.4

4.5

4.6

ψ(43S1)

X(3872)

DsJ*DsJ*

Is the narrow X(3872) state D0D* molecule?

Most states above DD not measured

Measure decay branching ratios. 3.4

4.1

4.8

5.5

6.3

7.1

8.0

9.3

10.3

Pla

b [GeV

/c]

May 19, 2005 Andrey Sokolov 7

PANDA Detector

May 19, 2005 Andrey Sokolov 8

1000 decays were simulated: Here D-mesons decayed at the point (0.1,0.1,0.4)mm. Kaon ID was required. Three tracks were refitted to the common vertex.

Simulation of the D-mesons

KD

Invariant mass of D - mesonVertex position

May 19, 2005 Andrey Sokolov 9

Reconstruction of D and Ds

mesons

Decay Br, % Efficiency, %

9.2 27

3.8 31

7.5 20

4.4 30*

KD

0

KD0

KKDs

KD

* Only one kaon identification is required.

May 19, 2005 Andrey Sokolov 10

Simulation of Ψ(4040)

Simulate 5 days data Initial S/B ratio 10-8

Simulated S/B ratio 3

The reaction have been studied

..00**)4040( ccKDDDD

Invariant mass difference between D*± and D0 mesons

Ψ(4040) invariant mass distribution

May 19, 2005 Andrey Sokolov 11

Summary

There are many open questions for open charm and charmonium above the DD threshold.

The PANDA experiment will be an excellent tool to answer these problems.

Good reconstruction efficiency for many types of D-mesons has been demonstrated.

Very high background suppression is achieved.

May 19, 2005 Andrey Sokolov 12

D*-decay

Momentum vs. polar angle distribution of decay product from reaction ..00**)4040( ccKDDDD