James Ritman Univ. Giessen New Opportunities for Hadron Physics with the Planned PANDA Detector Overview of the PANDA Physics Program The PANDA Detector

James Ritman Univ. Giessen

New Opportunities for Hadron Physics with the Planned PANDA Detector

• Overview of the PANDA Physics Program

• The PANDA Detector

• Selected Simulation Results– Charmonium: EM decays– Charmonium: Open charm decays– Charmonium in nuclear matter


What Do We Want To Know?

• Are there other forms of hadrons?e.g. Hybrids qqg or Glueballs gg

• Why are hadrons so much heavier than their constituents?

p-A interactions

• Why don‘t we observe isolated quarks?Q-Q potential in the charmonium system


Why Don’t We See Isolated Quarks?


Charmonium – the Positronium of QCD

3D2

2900

3100

3300

3500

3700

3900

4100

c(3590)

c(2980)

hc(3525)

(3097)

(3686)

(3770)

(4040)

0(3415)

1(3510) 2(3556)

3D1

3D3

1D2

3P2(~ 3940)

3P1(~ 3880)

3P0(~ 3800)

(~ 3800)

1 fm

C C

~ 600 meV -1000

-3000

-5000

-700011S

0

13S1

21S0 23S

121P

1 23P2

23P1

23P0

031S

0 31D

2 33D2

33D1

33D2

Ionisationsenergie33S

1

e+ e-0.1 nm

Binding energy [meV]

Mass [MeV]

DDThreshold

8·10-4 eV

10-4 eV

• Positronium • Charmonium


Why Antiprotons?

• e+e- annihilation via virtual photon: only states with Jpc = 1--

• In pp annihilation all mesons can be formed

• Resolution of the mass and width is only limited by the beam momentum resolution

Measured rate

Beam

Resonance cross

section

CM Energy


High Resolution

• Crystal Ball: typical resolution ~ 10 MeV

• Fermilab: 240 keV

p/p < 10-4 needed


Open Questions c (11S0) (Simu results)

experimental error on M > 1 MeV hard to understand in simple quark models

c’ (21S0)

Crystal Ball result way offstudy of hadronic decays

hc(1P1)

Spin dependence of QQ potentialCompare to triplet P-StatesLQCD NRQCD

9

)(5)(3)( 210 MMMM cog


Open Questions States above the DD threshold

Higher vector states not confirmed (3S), (4S) Expected location of 1st radial excitation of P wave statesExpected location of narrow D wave states Only (3770) seenSensitive to long range Spin-dependent potential

(Simu results)


Why Are Hadrons So Heavy?

Hadron Masses

Protons = (uud) ?2Mu + Md ~ 15 MeV/c2

Mp = 938 MeV/c2

(P.Kienle)

no low mass hadrons (except , K, )

spontaneously broken chiral symmetry

0qq


Hadron Production in the Nuclear Medium

c d_

d du

c_ d

repulsive

attractive

D-

D+d du

d du

d du

d du

d du

Quark atom

Mass of particles may change in dense matter( ) : 40

( ) : 200

s u

c d

K su m m

D cd m m

J/ Absorption in Nuclei

J/ absorption cross section in nuclear matter p + A J/ + (A-1)

(Simu results)


Comparison of p-A Reactions to A-A

Much lower momentum for heavy producedparticles (2 GeV for “free”)

(Effects are smaller at high momentum)

Well defined nuclear environment (T and )


The Experimental Facility

HESR


HESR: High Energy Storage Ring

Beam Momentum 1.5 - 15 GeV/c

High Intensity Mode:Luminosity 2x1032 cm-2s-1 (2x107Hz)p/p (st. cooling) ~10-4

High Resolution Mode:Luminosity 2x1031 cm-2s-1 p/p (e- cooling) ~10-5

http://www.fz-juelich.de/



Central Tracking Detectors• Straw-Tubes• Mini-Drift-Chambers

• MVD: (Si) 5 layers

• ~ 9 Mio pixelsAndrei Sokolov HK39.5

Thursday 15:00


PID

(DIRC@BaBar)

• ToF • Muon Detectors • DIRC


Open Charm

pp DD

DK

„no backgroundevents added“

Mass Resolution

~ 10 MeV/c2


Vertex Distributions GEANT4

D meson signal DPM background

Transverse

signal DPM background

Scale up by x10!0.15 < Vz < 5 mm

Longitudinal


DD Missing Mass

signal DPM background

N.B. different x scale| Mmiss 2|< 0.001 GeV2 (tight cut)


Open Charm

As an example of the Pbar P (3770) DD AnalysisPlot MDD – MD – MD + 2x1869MeV

raw S/B ~ 10-7


Detection of Rare Neutral ChannelsAs an example: cBackground:

c 1:50:500

Comparison with E835(PLB 566,45)

PANDA


Dimuon Spectrum in p+Cu• Beam momentum “on resonance” • Full background simulations

(result scaled up)• Muons from J/ have high Pt• J/ has low Pt (coplanar)

J/


Summary

• GSI will explore the intensity frontier

• High luminosity cooled p from 1-15 GeV/c

• Wide physics program including

• Charmonium spectroscopy

• pbar-A reactions

• Search for glueballs and charm hybrids



In part supported by:GSIBMBF 06GI144DFG


Target• A fiber/wire target will be needed for D physics,• A pellet target is conceived:

1016 atoms/cm2 for D=20-40m

1 mm


Electromagnetic CalorimeterDetector material PbWO4

Photo sensors Avalanche Photo Diodes

Crystal size 35 x 35 x 150 mm3 (i.e. 1.5 x 1.5 RM2 x 17 X0)

Energy resolution 1.54 % / E[GeV] + 0.3 %

Time resolution 130 ps (N.B. with PMT!)

Total number of crystals 7150


Tracking Resolution

J/ K+K- (J) = 35 MeV/c2

() = 3.8 MeV/c2

Example reaction: pp J/ (s = 4.4 GeV/c2)

Single track resolution

Invariant mass resolution


Staged Construction


Pbar-Nucleus InteractionsThe interaction of charmed mesonswith the baryonic environment strongly effects production rates near threshold

Strange Baryons in Nuclear FieldsHypernuclei open a 3rd dimension (strangeness) in the nuclear chart

-

3 GeV/c

K+KTrigger

_

secondary target

p

• Double-hypernuclei: very little data

• Baryon-baryon interactions: -N only short ranged (no 1 exchange due to isospin) impossible in scattering reactions

-(dss) p(uud) (uds) (uds)


Probe large separations with highly excited qq states_

Charmonium Spectroscopy


The GSI Future Project

• Heavy Ion Physics: hot and dense nuclear matter

• Nuclear Structure: paths of nucleo-synthesis

• Ion and laser induced Plasma: very high energy densities• Atomic physics: QED, strong EM fields, Ion-Matter interactions• Physics with Antiprotons properties of the strong force

Project approved Feb 2003


Open Questions

• The c(11S0)

• The c(21S0)

• The hc(1P1)

• States above the DD threshold


Proton Form Factors at large Q2

At high values of momentum transfer |Q2| the system should be describable by perturbative QCD. Due to dimensional scaling, the FF should vary as Q4.

222 lns

s

CG

p

M

q2>0

q2<0

The time like FF remains about a factor 2 above the space like. These differences should vanish in pQCD, thus the asymptotic behavior has not yet been reached at these large values of |q2|. (HESR up to s ~ 25 GeV2)


Mixing With Mesonic States

Width: could be narrow (5-50 MeV) since

DD suppressed for some states

O+- DD,D*D*,DsDs (CP-Inv.)

(QQg) (Qq)L=0+(Qq)L=0 (Dynamic Selection Rule)

If DD forbidden, then the preferred decay is

(ccg) (cc) + X , e.g. 1-+

Ex

oti

c lig

ht

qq

Ex

oti

c cc

1 - - 1 - +

0 2 0 0 0 4 0 0 0M e V / c2

10 - 2

1

1 0 2

Spontaneous Breaking of Chiral Symmetry

Although the QCD Lagrangian is symmetric, the ground state need not be. (e.g. Fe below TCurie )

Example:


Exotic Hadrons


Glueballs

gg

g

RG

GR

BGGRRB

C. Morningstar PRD60, 034509 (1999)Self interaction between gluons

Construction of color-neutral hadrons with gluons possible

exotic glueballs don‘t mix with mesons (qq)

0--, 0+-, 1-+, 2+-, 3-+,...


RBRB

Prediction in QCD:

Collective gluon excitation

(Gluons contribute to quantum numbers)

Ground state: JPC = 1-+ (spin exotic)

Charm Hybrids ccg

distance between quarks


Partial Wave Analysis

Partial wave analysis as important tool

Example of 1-+ (CB@LEAR)pd X(1-+)++p, X

Strength ~ qq States !

Signal in production but not in formation is interesting !


Quark Condensate

The QCD vacuum is not empty 0qq

Hadron masses are generated by the strong interaction with <qq> (also with gluon condensate)

The density of the quark condensate will change as a function of temperature and density in nuclei.

This should lead to modifications of the hadron’s spectral properties.

Hadrons in the Nuclear Medium

Spectral functions

W.Peters et al., Nucl. Phys. A632, 109 (1998).S.Klimt et al., Nucl. Phys. A515, 429 (1990).

<qq>

Reduction of <qq>


Deeply Bound Pionic Atoms

Pionic capture is possible with the appropriate choice of kinematics:

d+n 3He + -

These results indicate a mass shift of ~25 MeV for pions at normal nuclear matter density.


J.Schaffner-Bielich et al., Nucl. Phys. A (1997) 325.

Kaons in Nuclear Matter

Kaon and anti-kaon masses should no longer be degenerate in nuclear matter.

Expected signal: increased K- production compared to K+.


Measured K- Cross Section

[1] A.Sibirtsev et al., Z.Phys. A358 (1997) 101.[2] F.Laue et al., Phys.Rev. Lett. 82 (1999) 1640.[3] C.Quentmeier et al., Phys Lett B 515 (2001) 276.

KaoS

dramatic enhancement of the K- production probability

Comparison of proton-proton data with heavy ion data[2]:


Open Charm in Nuclei

The interaction of charmed mesons with the baryonic environment strongly effects production rates near threshold


cc Production in Nuclear Matter

The mass of charmonium states is not expected to change much.

However, a drop of the DD mass leads to a widening of the ccstates.

’ will have too high momentum, most decay outside. but wider tails


Charmonium in NucleiDue to the increased width, the dileptons from charmonium states below the free DD threshold are strongly suppressed.

Golubeva et al. Eur.Phys.J. A17 (2003) 275-284

Documents

James Ritman Univ. Giessen New Opportunities for Hadron Physics with the Planned PANDA Detector Overview of the PANDA Physics Program The PANDA Detector