Transcript Slide 1
„EMMI Workshop and XXVI Max Born Symposium”
Wrocław 9-11.07.2009
Probing resonance matter with HADES
P. Salabura
Jagiellonian University/GSI
for the HADES collaboration
Baryonic matter at 1-2 AGeV
Au+Au
~10fm/c
moderate densities but long system life time
Baryonic matter:
• /N
= 1-3, T< 80 MeV, ~15 fm/c
nucleons, baryonic resonances (~30%) 33, mesons(π0)~10%
“resonance matter”
HADES
Composition of a barionic matter
Rear probes: dielectrons & strangeness
What is still (after >20 years) exciting in this field ??
•
e.m radiation from „resonance matter” – excess
connection to / in-medium properties ?
• Sub-threshold strangeness production:
, K+ K- , - (1321)
Dielectrons from C+C @ 1.0 GeV
DLS Data: Phys.Rev.Lett. 79 (1997) 1229
HADES : Phys. Lett. B 663 (2008) 43
2008
-2
DLS
W. Cassing,
E.L. Bratkovskaya Physics
1.0 A GeV
10Data & Transport (1999) :C+C,
Reports 308 (1999) 65
no medium effects
HADES
2
1/N dN/dM [1/GeV /c ]
10
10
-4
10
-5
10
-6
Brems. NN
Brems. N
All
10
-7
10
-8
0.0
HADES data projected into DLS acceptance
0.2
0.4
0.6
0.8
E.L. Bratkovskaya and W. Cassing NPA 807, 214 (2008) &
new. -2N-N bremss.OBE Kaptari
NPA 764 (2006) 338
C+C, 1.0&AKämpfer
GeV
10
10
-3
10
-4
10
-5
in-medium effects: CB+DM
Excess ?? above what?
HSD:
do we have a good
reference ? Dalitz
HADES
2
M [1/GeV /c ]
Very good agreement between 2 experiments
full confirmation of DLS effect
HSD:
Dalitz
Dalitz
Dalitz
Dalitz
-3
Dalitz
Dalitz
Dalitz
known
.. frankly speaking, no!
elementary e+e- sources not fully
Brems. NN
Reference: dielectrons from pp and
“quasi-free” pn @ 1.25 AGeV
Model Calculations:
a) NNNNe+e- OBE calculations Kaptari & Kämpfer (K&K) NPA 764 (2006) 338
b) , yield constraint by data. Dalitz decay Krivoruchenko et al. Phys. Rev. D 65 (2001) 017502 + VMD formfactor (Q. Wan and F. Iachello, Int. J. Mod. Phys. A 20 (2005) 1846)
pp/pn data are not described by recent OBE calculations !
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Excess or no excess ?
F~3
C+C data reproduced (within 20%) by superposition of NN interactions (reference)
& scaling with pion production
Larger system size – Ar+KCl (4 larger Apart)-first evidence for the in-medium effect
– baryonic radiation : i.e NN N N .. (fireball ~10x ) !
Different mechanism as at SPS ( pion annihilation)
Vector mesons / at SIS
p+ 92Nb 3.5 GeV
p+p at 3.5 GeV
40Ar+ 38KCl
2008
“on-line spectrum!”
1.75 AGeV
2005
preliminary
sM() 15 MeV/c2
• Systematic studies on / production at SIS has been started
• Verification of p+A from KEK (advantage lower beam energy ) & CBTAPS/CLAS
• Only consistent description of the pp/p+A/and A+A can give full picture
K+ K- / - production at SIS
Strangeness Exchange : belived to be dominant
NN NK
K N
via ?
sub-threshold, OZI suppressed ?
NN NNK K
N NK K
non-resonant
NN NN
N NN
resonant (->K+K- )
- (1321) S=-2
deep subthreshold (~600 MeV) not measured
KY
Strangeness Exchange +
network of reactions sensitvity to EOS
SIS?
A.
B.
Andronic, P. Braun-Munzinger,
K. Redlich, NPA 765 (2006)
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/ Production in ArKCl @ 1.75AGeV
s =236 MeV
M =1017,8 ± 0.9 MeV/c2
s = 6.2 MeV/c2
e+ee+eS. Wheaton and J. Cleymans, hep-ph/0407174
/ ~1 fixed to pp data , yield in line with mT scal.
R(/) = 4.2*10-3 *f
OZI rules for N-N
enhanced R(/) in HI as compared to N-N()
close to stat. model (THERMUS) !(no suppression)
different absorption?
OZI
/ K- ratio
Statistical model K. Redlich, H. Oeschler-priv.comm
Teff=693
HADES: accepted PRC: arXiv:0902.3487
Teff=894
Teff=848
/K- =0.340.13 & is enhanced
is important source of K- in HI collisions at
SIS
- production in Ar+KCl @ 1.75 AGeV
identification:
p
HADES data
THERMUS fit S. Wheaton and J.
Cleymans, hep-ph/0407174
T= 703 b=74615 (MeV)
RC =2.6 0.4 fm
Rfireball =6 0.7 fm
2=2.1 (no - )
?
p
23.01.2009
P.Salabura
Outlook: future exp.
2008/9/10
2009-2011
SIS18
2010
Upgrade RPC, DAQ, MDC1, EM Calorimeter (for SIS100)
Ag +Ag @ Au+Au
+ N, + A
dielectrons (/) , strangeness (K-K+ . ,)
resonance (, N*) radiative decays, strangeness
2011
> 2013
(SIS100)
Hades goes to FAIR ( 8 AGeV)
increase of Mul(/) by 2 orders of magnitue !!
CBM
HADES
23.01.2009
The Collaboration
Catania (INFN - LNS), Italy
Cracow (Univ.), Poland
Darmstadt (GSI), Germany
Dresden (FZD), Germany
Dubna (JINR), Russia
SIS
Frankfurt (Univ.), Germany
Giessen (Univ.), Germany
Milano (INFN, Univ.), Italy
München (TUM), Germany
Moscow (ITEP,MEPhI,RAS), Russia
Nicosia (Univ.), Cyprus
Orsay (IPN), France
GSI
Rez (CAS, NPI), Czech Rep.
Sant. de Compostela (Univ.), Spain
Valencia (Univ.), Spain
23.01.2009
Coimbra (Univ.), LIP, Portugal
P.Salaura
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BACK-UP SLIDES
23.01.2009
P.Salabura
Conference
High Acceptance Di-Electron Spectrometer
Side View
Beams from SIS18: pions, protons, nuclei
high invariant mass resolution (2% at / mass)
and powerful PID capabilities : p/π/K/e
Large acceptance for sys. studies :
•
dielectrons (e+,e-)
•
strangeness: K,0 , , ,
FW
START
Geometry
1m
Full azimuth, polar angles 18 - 85
e+e- pair acceptance 0.35
~ 80.000 channels, segmented solid or LH2 targets
P.Salabura
3
N-N Bremsstrahlung
• Strong
+
electromagnetic process (OBE models)
e+
+
=
(simplified picture!)
e1
+
2
1
2
NN ("quasielastic")-non resonant
resonant -baryon resonances ()
collection of results from E.L
Bratkovskaya & W. Cassing:
E.L. Bratkovskaya and W. Cassing arXiv:0712.0635v1 Nucl.Phys A 807, 214 (2008).
• bremsstrahlung OBE
calculations:
Kaptari & Kämpfer, NPA 764 (2006)
338:
K&K OBE calculation:
pn bremsstrahlung 4 larger
23.01.2009
P.Salabura
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e+e- Invariant mass spectrum decomposition
e+e- decays
pp @3.5 GeV
• Mesons (known)
0
,g
e+
,
e-
• Baryon resonances (not measured !) –
important at lower beam energies SIS18
/
N
e+
eExample cocktail
HADES data p+p @ 3.5 GeV
compared to model calc.
•Two-body decays (known):
e+
//
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g*
eP.Salabura
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Vector mesons: pairs from DLS
Data:
Calculations: C.Ernst et alPhys. Rev. C58 (1998)
• Coupling of to N*(1520), N*(1700) ?
• Coupling of to N*(1535) ?
DLS
Relevant for in-medium :
extended VDM
Ch. Fuchs Phys. Rev. C68
(2003) 014904
• signal not visible due to resolution
• enhancement below / pole – resonance radiation ?
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Conference
Invariant Mass Spectra of , K S0 and
K S0
p
145.000
51.000 K S
S/B 0.3
s 2.4 MeV/c
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0
2
S/B 1.0
s K0
9.1 MeV/c2
S
P.Salabura
K K
168
S/B 1.1
s 6.2 MeV/c
2
Conference
K0-Nucleon Potential
Results from FOPI (HSD)
Kaon-Nucleon Potential: 30 MeV @ =0
(HADES and IQMD)
KN-Potential is repulsive
with a strength of U=20 MeV
C. Hartnack, J. Aichelin, H. Oeschler
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P.Salabura
Conference
p+p @ 1.25 GeV - Dalitz decay
Dalitz decay
p
+
PRELIMINARY
g*
e+
q2 = M2inv(e+e-) = Mg*2 > 0
e-
QED
grey band Iachello. VMD
Time-like - N transition
branching ratio BR(M) ?
EM-formfactors (GM , GE, GC)?
d (Δ Ne e - )
f
dq 2
2
q
2
2
2
2
2
m Δ, q G M q 3 G E q 2 m 2
Δ
G q
2
2
C
VMD
PLUTO calculations:
a) NN-bremsstrahlung Kaptari & Kämpfer (K&K)
b) Dalitz decay
Krivoruchenko et al. Phys. Rev. D 65 (2001) 017502 +
VMD form-factor (Q. Wan and F. Iachello, Int. J. Mod. Phys. A 20 (2005) 1846)
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d+ppspec e+e-X @ 1.25 AGeV –
„quasifree” p-n collisions
neutron
„target” proton
e+ e–
pspec
PRELIMINARY
proton
pc
neutron
selection of np reactions via
spectator proton in Forward Wall
spectator "tag"
Mult. 1 FW (0.5–7)
cocktail:
a) np-Bremsstrahlung a-la Kaptari & Kämpfer,
and (constrained by data)
b) Fermi momentum of nucleon in deuterium from N-N
Bonn potential
23.01.2009
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No satisfactory description
of pp and pn data!!
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Particle IDentification
HADRONS
Momentum vs velocity (β)
LEPTONS
(RICH tagging)
ep
1
e+
q p
Target
RICH
2
Minv = 2 sin( / 2) p1 p 2
dE/dx in MDC & TOF
hadron : lepton suppression ~10-4
Kaon identification
log. z axis !
e+
e-
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