PowerPoint-Pr

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• motivation (predicted medium effects in the
  charm sector)

• first observation of medium modifications of
  the ? meson
• a.) mass shift
• b.) in-medium width

• summary and outlook

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Motivation

• QCD-vacuum complicated structure
• characterized by condensates

• in the nuclear medium
• condensates are changed
• change of the hadronic excitation
• energy spectrum

• widespread experimental activities to search for
  
• in-medium modifications of hadrons

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possible in-medium modifications of hadrons

• in-medium mass shift
• (partial restoration of chiral symmetry,
  meson-baryon coupling)

• in-medium broadening of hadron resonances
• (meson-baryon coupling, collisional broadening)

• hadron-nucleus bound states
• (meson-nucleus attractive potential)

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model predictions for in-medium masses of mesons
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predictions in the charm sector
consequences of a dropping D-meson mass
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Model predictions for spectral functions of r and
w mesons
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?-, ?-meson-nucleus potential
K. Saito, K. Tsushima, A.W. Thomas, hep-ph/0506314
predictions within the quark meson coupling model
(QMC)
? E(1s) -39 MeV ? 29 MeV ? E(1s) -100
MeV ? 31 MeV
? E(1s) -56 MeV ? 33 MeV ? E(1s) -118
MeV ? 33 MeV
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Predictions of nuclear bound quarkonium states

• S. Brodsky et al. , PRL 64 (1990) 1011

attractive cc nucleon potential due to multi
gluon exchange ? ?c binding energy to light
nuclei of the order of ? 20 MeV

• Klingl et al., PRL 82 (1999) 3396

QCD sum rules attractive mass shift of ? 5-10
MeV for J/? and ?c

• K. Saito et al., hep-ph/0506314

D- - nucleus bound states (superposition of
Coulomb strong interaction)
D- 208Pb (1s) bound by 24 MeV
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experimental approach dilepton spectroscopy r,
w, f ? ee-
essential advantage no final state interactions
!!

• CLAS (Jlab) C. Tur et al., ?A ??, ?, ? X

• HADES (GSI) planned experiment ?- p ? ? n on
  bound proton

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?-mass in nuclei from photonuclear reactions
advantage p0g large branching ratio (8 )
no ?-contribution (? ? ?0? 7 ? 10-4)
disadvantage p0-rescattering
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Expected ? in-medium signal
rescattering of pions in nuclei predominantly
proceeds through ?(1232) excitation scattered
pions have Ekin?150 MeV
no distortion by pion rescattering expected in
mass range of interest
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comparison of meson masses and lineshapes for LH2
and nuclear targets
?0
?
??
No change of mass and lineshape for longlived
mesons (?0, ?, ??) decaying outside nuclei
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inclusive ???0? signal for LH2 and Nb target
D. Trnka et al., PRL 94 (2005)192303
difference in line shape of ? signal for proton
and nuclear target
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D. Trnka, PhD thesis, Univ. Giessen 2006
decomposition of ? signal into in-medium and
vacuum decay contributions
Nb in-medium 45
C in-medium 40
lineshape of vacuum contribution taken from LH2
experiment
shape of in-medium contribution taken from BUU
simulation (P. Mühlich and U. Mosel, NPA
(2006)), assuming m? m0(1 - 0.16 ?/?0)
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access to in-medium ? width
in-medium ? width proportional to ? absorption ?
? ?v?abs
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access to in-medium ? width
in-medium ? width proportional to ? absorption ?
? ?v?abs
normalization to C!! E?1.5 GeV
Comparison to data taken at E? 1.45-1.55 GeV
(D.Trnka et al.(preliminary))
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dependence of ? width on ? momentum

• ? gets broadened in the medium by a factor 10!!

• transparency ratio measurement also possible
  for charmed mesons in the
• nuclear medium ? ? inel (p) ? ?(p)
  (J/?-suppression in AA collisions)

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momentum dependence of ? signal (Nb-target)
D. Trnka et al., PRL 94 (2005)192303

• mass modification only for p?? 0.5 GeV/c

determination of momentum dependence of ? -
nucleus potential requires finer momentum bins
? improved 2nd. generation experiment
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correlation between ? momentum and proton angle
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D. Trnka, PhD thesis, Univ. Giessen 2006
comparison of data on LH2 and C
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population of charmed meson bound states??
? No chance for populating a state bound with 20
MeV!!!
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(allowing for phase space of 3 GeV)
in the laboratory minimum J/?(1s) momentum 4.4
GeV/c ? ?J/?
0.82 Ekin(J/?) 2.28 GeV
no chance of forming a J/?- nucleus bound state!!
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Summary and outlook
major step forward towards understanding the
origin of hadron masses

• first evidence for ? mesic 11B

? second generation experiments with improved
statistics are needed and in preparation
? difficult to transfer techniques and approaches
to the charm sector !!
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CBELSA/TAPS collaboration
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Flatte fit to TAPS data
M. Pfeiffer et al., PRL 94 (2005)
finer energy binning
2 poles m-i?/2 (1487.7-i4.8) MeV
(1483.9-i8.9) MeV
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Prediction of ? mesic states in QMC and QHD models
K. Saito, K. Tsushima, A.W. Thomas,
hep-ph/0506314
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Search for ? mesic states in heavier nuclei
C. Garcia-Recio et al., PLB 550 (2002)
47 unitarized chiral model
preferably only 1s-state 24Mg B12.6 MeV ?33
MeV
experiment at COSY (ENSTAR/Big-Karl) Roy et al.
p 12C ? 3He ?10B p 6Li ? 3He ?4He
experiment at GSI Hayano et al., EPJ A6 (1999)
105 7Li(d,3He)?6He Td 3.6GeV
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Prediction of ? mesic states
E. Marco and W. Weise, PLB 502 (2001) 59
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Ye.S.Golubeva et al., nucl-th/0212074
? (3770)
A. Hayashigaki, PLB487 (2000) 96