Physics with open charm mesons at

Andrey SokolovAndrey SokolovInstitute of Nuclear PhysicsInstitute of Nuclear Physics,,

Research Center Jülich, Research Center Jülich, GermanyGermany

The structure and dynamics of hadrons International Workshop XXXV on Gross Properties of Nuclei and Nuclear

Excitations, Hirschegg, Kleinwalsertal, Austria, January 14 - 20, 2007

Outline: Physics foundations; Experimental techniques; Capabilities of the PANDA@FAIR; Summary.

Andrey SokolovAndrey Sokolov 2

Panda Physics Overview Charmonium spectroscopy:

Precision M and Γ measurement: qq – potential. New states above DD threshold.

Charmed hybrids and glueballs; Interaction of charmed particles with nuclei; Hypernuclei; Further options:

Open charm physics Wide angle compton scattering; Baryon-Antibaryon production; CP-Violation (Λ,D).

Andrey SokolovAndrey Sokolov 3

Charmonium spectroscopyThe energy region above the DD threshold is very

poorly known: The higher vector states ((3S), (4S), (5S) ...)

have not all been confirmed by the latest measurements by BES.

In this region the narrow D-states are expected!!!

Andrey SokolovAndrey Sokolov 4

Charmonium Spectroscopy

M = 3872. 0 0.60.5MeV

< 2.3 MeV at 90% C.L.

by CDF

11.6 effect

A new narrow resonance called X(3872) was observed in 2003:

X(3872) 10 effect

’J/

by BELLE

The other states Y(3940), Y(4260), X(3943), Z(3934), ψ(4320) have been observed in recent years

Andrey SokolovAndrey Sokolov 5

DsJ

(2458)

Open Charm Spectroscopy

0 1 0 1 2 3

Ds

Ds*

DsJ*

(2317)

Ds1

m [G

eV/c

2 ]

D0K

D*KDs2

*

JP

}j=3/2}j=1/2

In Heavy-Light systems like H-atom; ordered by property

of the light quark; approximate j

degeneracy; the large gap between

j=3/2 and j=1/2 was unexpected.

j=L+sL

J=j+sH

in 2003 BaBar and CLEO observed two new narrow Ds mesons with surprisingly low masses.

The Ds± Spectrum

|cs> + c.c. was not expected to reveal any surprises, but…

Andrey SokolovAndrey Sokolov 6

(cs) – A Heavy-Light System

Andrey SokolovAndrey Sokolov 7

e+e- interactions: Only 1-- states are directly formed; Other states require:

ISR; B meson decays; higher order process

(γγ fusion).

pp reactions: All meson states directly formed

(very good mass resolution) other states can be studied using

production mechanism.

Production mechanism

} low cross-section, mass resolution determined by detector performance

EC

M

Andrey SokolovAndrey Sokolov 8

Energy dependency of cross section for HH

Effect of finite momentum spread

Andrey SokolovAndrey Sokolov 9

Benchmark Channels Analysis

Following reaction were chosen to demonstrate the physics performance of the PANDA detector:

..)3770( _ ccpp KDD

KKDDDDD

or

pp__0

00** ,)4040(

..)2317()2317( _00** ccpp KKDDDD sssJsJ ..)2460()2460( _ ccpp KKDDDD sssJsJ

Andrey SokolovAndrey Sokolov 10

Production cross-section

The production cross-section was estimated using the Breit-Wigner formula:

,)]/)(2[1)(4(

)(4)(

2242

2

RRp

outin

R cMscs

BBcs

m

,104.8/)/())3770(( 6

)3770(/

Jin

ppJBppBB

,107.3.).)3770(( 3 ccKDDBBout

..)3770( _ ccpp KDD

as a result the maximum total cross-section is: ,5.27 pbR

and the signal to background ratio is: 10

2

11

101.6105.41075.2

)()(

Xpp

signal

Andrey SokolovAndrey Sokolov 11

Proposed PANDA Detector

beam

Andrey SokolovAndrey Sokolov 12

Micro-Vertex Detector Displaced vertices of open charm and strangeness

with precision ~ 70 μm; Build on ATLAS experience with hybrid detectors; Silicon pixel (2-4 layers) and strips (2 layers); ~7.2 million barrel pixels, ~2 million forward pixels; R&D:

Requirements on pixel size and orientation; Investigate photon conversions; Electronics.

Andrey SokolovAndrey Sokolov 13

400mm

300m

m

Micro-Vertex Detector

Andrey SokolovAndrey Sokolov 14

Simulation of ψ(3770) Selection criteria:

Kaon ID (only by DIRC and RICH); D-meson invariant mass; D-meson secondary vertex fit; Kinematical constrain on ψ(3770) mass; Missing mass selection (Invariant mass resolution σ=10MeV).

Single D-meson reconstruction efficiency - 26%; ψ(3770) reconstruction efficiency - 4.2%; Background suppression factor - 2×109; Signal/background ratio ~ 3.

Andrey SokolovAndrey Sokolov 15

Reconstruction of D and Ds

mesonsDecay Br, [%] Efficiency, [%]

9.2 26

3.8 25

7.5 8

4.4 ~28*

KD0

KD0

KKDs

KD

* Only one kaon identification is required.

Andrey SokolovAndrey Sokolov 16

Total Reconstruction Efficiency

Reaction Efficiency, [%]

4.2

3.6

0.92

4.6*

3.3*

* Only one kaon identification is required.

..)3770( _ ccpp KDD

DDDDpp 00**)4040(

)2317()2317( **

DD sJsJpp

)2460()2460( DD sJsJpp

Andrey SokolovAndrey Sokolov 17

Summary

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

The PANDA detector will perform high resolution spectroscopy with p-beam and provide new data on this topic.

The Micro-Vertex Detector was designed for the reliable detection of D-mesons and its decay products.

Simulation results demonstrate the good reconstruction efficiency for D-mesons.

Very high background suppression is achieved.

Andrey SokolovAndrey Sokolov 18

Panda Participating Institutes more than 300 physicists (48 institutes) from 15 countries:

U BaselIHEP BeijingU BochumU BonnU & INFN BresciaU & INFN CataniaU CracowGSI Darmstadt TU DresdenJINR Dubna (LIT,LPP,VBLHE)U EdinburghU ErlangenNWU EvanstonU & INFN FerraraU FrankfurtLNF-INFN Frascati

U & INFN GenovaU GlasgowU GießenKVI GroningenU Helsinki IKP Jülich I + IIU KatowiceIMP LanzhouU MainzU & Politecnico & INFN MilanoU MinskTU MünchenU MünsterBINP NovosibirskLAL Orsay

U PaviaIHEP ProtvinoPNPI GatchinaU of SilesiaU StockholmKTH StockholmU & INFN TorinoPolitechnico di TorinoU Oriente, TorinoU & INFN TriesteU TübingenU & TSL UppsalaU ValenciaIMEP ViennaSINS WarsawU Warsaw

Andrey SokolovAndrey Sokolov 19

New Charmonium Resonances X(3872), Belle 09’2003, 1++, χc1´ or D0D* molecule

decays into J/ψπ+π-, J/ψπ+π-π0, J/ψγ, D0D*

Y(3940), Belle 09’2004, JP+, 23P1 or Hybrid?? decays into J/ψω

Y(4260), BaBar 06’2005, 1--, 23D1 (BaBar) or 43S1 (CLEO) or Hybrid decays into e+e-, J/ψπ+π-, J/ψπ0π0, J/ψK+K-

X(3943), Belle 07’2005, 0-+, ηc´´ decays into D0D*

Z(3934), Belle 07’2005, 2++, χc2´ decays into γγ, DD

ψ(4320), BaBar 06’2006, ?, Hybrid

Andrey SokolovAndrey Sokolov 20

Threshold Measurement

at threshold:

far above threshold:

ratio depends only on , M, and s

p p X X :_ _

A. Gillitzer

Andrey SokolovAndrey Sokolov 21

Facility for Antiproton and Ion Research

HESR

100 m

Andrey SokolovAndrey Sokolov 22

from RESR

High Energy Storage Ring

Storage ring for p: Np = 5×1010, Pbeam= 1.5-15 GeV/c;

High density target: pellet 1015 atoms/cm3, cluster jet,

wire;

High luminosity mode: Δp/p = 10-4, stochastic cooling,

L = 1032 cm-2s-1;

High precision mode: Δp/p = 3×10-5, electron cooling,

L = 1031 cm-2s-1.

Andrey SokolovAndrey Sokolov 23

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

Andrey SokolovAndrey Sokolov 24

ψ(3770) Invariant Mass Resolution σ(Minv) = 10 MeV