Probing resonance matter with HADES

„„EMMI Workshop and XXVI Max Born Symposium””

Wrocław 9Wrocław 9--1111.0.077.2009.2009

P. Salabura

Jagiellonian University/GSI

for the HADES collaboration

BBaryonic matter aryonic matter at 1-2 AGeVat 1-2 AGeV

Au+Au

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”

What is still (after >20 years) exciting in this field ??

• e.m radiation from „resonance matter” – excessconnection to / in-medium properties ?

• Sub-threshold strangeness production: , K+ K- , - (1321)

~10fm/c

Composition of a barionic matter Rear probes: dielectrons & strangeness

HADES

Dielectrons from C+C @ 1.0 GeV DLS Data: Phys.Rev.Lett. 79 (1997) 1229

HADES : Phys. Lett. B 663 (2008) 43

HADES data projected into DLS acceptance

Very good agreement between 2 experiments full confirmation of DLS effect

DLS Data & Transport (1999) : W. Cassing, E.L. Bratkovskaya Physics Reports 308 (1999) 65

Excess ?? above what? do we have a good reference ? .. frankly speaking, no! elementary e+e- sources not fully known

0.0 0.2 0.4 0.6 0.810-8

10-7

10-6

10-5

10-4

10-3

10-2

0.0 0.2 0.4 0.6 0.810-8

10-7

10-6

10-5

10-4

10-3

10-2

HADES

HSD: Dalitz Dalitz Dalitz Dalitz Brems. NN Brems. N All

C+C, 1.0 A GeVno medium effects

1/N

dN/d

M

[1/G

eV /c

2 ]

HSD: Dalitz Dalitz Dalitz Dalitz Brems. NN Brems. N All

M [GeV/c2]

HADES

C+C, 1.0 A GeVin-medium effects: CB+DM

1/N

dN/d

M

[1/G

eV /c

2 ]E.L. Bratkovskaya and W. Cassing NPA 807, 214 (2008) & new. N-N bremss.OBE Kaptari & Kämpfer NPA 764 (2006) 338

2008

Reference: dielectrons from pp and Reference: dielectrons from pp and “quasi-free” pn @ 1.25 AGeV“quasi-free” pn @ 1.25 AGeV

pp/pn data are not described by recent OBE calculations !12

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 form-factor (Q. Wan and F. Iachello, Int. J. Mod. Phys. A 20 (2005) 1846)

Excess or no excess ?Excess or no excess ?

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)

preliminary

F ~ 3

Vector mesons Vector mesons // at SIS at SIS

p+p at 3.5 GeV

2005

40Ar+ 38KCl 1.75 AGeVp+ 92Nb 3.5 GeV

2008“on-line spectrum!”

• 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

M() 15 MeV/c2

preliminary

preliminary

preliminary

KK++ K K-- / / -- p production at SIS roduction at SIS

NNNNKNNKNN

via ?

Strangeness Exchange : belived to be dominant

NK

NKNN

non-resonant resonant (->K+K- )

NNNKNKN

19

sub-threshold, OZI suppressed ?

- (1321) S=-2 deep subthreshold (~600 MeV) not measured

Strangeness Exchange + network of reactions sensitvity to EOS

KYA. Andronic, P. Braun-Munzinger,B. K. Redlich, NPA 765 (2006) SIS?

// Production in ArKCl @ 1.75AGeV Production in ArKCl @ 1.75AGeV

/ ~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?

M =1017,8 ± 0.9 MeV/c2

= 6.2 MeV/c2

e+e-e+e-

=236 MeV

OZI

preliminary

S. Wheaton and J. Cleymans, hep-ph/0407174

// K K-- ratio ratioStatistical model K. Redlich, H. Oeschler-priv.comm

Teff=693

Teff=894

/K- =0.340.13 & is enhanced is important source of K- in HI collisions at SIS

HADES: accepted PRC: arXiv:0902.3487 

Teff=848

-- p productionroduction in Ar+KCl @ 1.75 AGeV in Ar+KCl @ 1.75 AGeV

23.01.2009P.Salabura

identification: p

p

HADES data

THERMUS fit S. Wheaton and J. Cleymans, hep-ph/0407174

?

T= 703 b=74615 (MeV)RC =2.6 0.4 fmRfireball =6 0.7 fm 2=2.1 (no - )

preliminary

23.01.2009

Outlook: future expOutlook: future exp..Upgrade RPC, DAQ, MDC1Upgrade RPC, DAQ, MDC1, EM Calorimeter (for SIS100), EM Calorimeter (for SIS100)2008/92008/9/10/10

Hades Hades goes togoes to FAIR ( 8 AGeV) FAIR ( 8 AGeV)> 2013> 2013 (SIS100)(SIS100)

20112011

+ N, + N, + A + A resonance ( resonance (, N, N**) radiative decays, strangeness ) radiative decays, strangeness

20102010

AgAg + +AgAg @ @ Au+Au Au+Au dielectrons ( dielectrons (//) , strangeness (K) , strangeness (K--KK+ + . . , ,))2009-20112009-2011

SIS18SIS18

increase of Mul(/) by 2 orders of magnitue !!

CBM

HADES

23.01.2009 P.Salaura 12

The CollaborationThe Collaboration

GSIGSI

SISSIS

Catania (INFN - LNS), Italy

Cracow (Univ.), Poland

Darmstadt (GSI), Germany

Dresden (FZD), Germany

Dubna (JINR), Russia

Frankfurt (Univ.), Germany

Giessen (Univ.), Germany

Milano (INFN, Univ.), Italy

München (TUM), Germany

Moscow (ITEP,MEPhI,RAS),

Russia

Nicosia (Univ.), Cyprus

Orsay (IPN), France

Rez (CAS, NPI), Czech Rep.

Sant. de Compostela (Univ.), Spain

Valencia (Univ.), Spain

Coimbra (Univ.), LIP, Portugal

23.01.2009 P.Salabura

BACK-UP SLIDESBACK-UP SLIDES

Conference

Side View

START

FWFW

3

High Acceptance DiHigh Acceptance Di-E-Electron Spectrometerlectron Spectrometer

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 , , ,

GeometryFull azimuth, polar angles 18 - 85 e+e- pair acceptance 0.35~ 80.000 channels, segmented solid or LH2 targets

1 m

P.Salabura

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N-N Bremsstrahlung

E.L. Bratkovskaya and W. Cassing arXiv:0712.0635v1

NN ("quasielastic")-non resonant

• Strong + electromagnetic process (OBE models)

1

2

e+

e- + =

resonant -baryon resonances ()

1

2

+

collection of results from E.L Bratkovskaya & W. Cassing: Nucl.Phys A 807, 214 (2008).

• bremsstrahlung OBE calculations:

Kaptari & Kämpfer, NPA 764 (2006) 338:

K&K OBE calculation:

pn bremsstrahlung 4 larger

(simplified picture!)

10

16

e+e- e+e- Invariant mass spectrum decompositionInvariant mass spectrum decomposition

e+e- decays

• Mesons (known)

• Baryon resonances (not measured !) – important at lower beam energies SIS18

•Two-body decays (known):

e+

e-

e+

e-

e+

e-

Example cocktailHADES data p+p @ 3.5 GeV compared to model calc.

pp @3.5 GeV

0

/

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DLS

Vector mesons: pairs from DLS

Data: Calculations: C.Ernst et alPhys. Rev. C58 (1998)

• signal not visible due to resolution

• enhancement below / pole – resonance radiation ?

• Coupling of to N*(1520), N*(1700) ?

• Coupling of to N*(1535) ?

Relevant for in-medium :

extended VDM

Ch. Fuchs Phys. Rev. C68 (2003) 014904

Conference

Invariant Mass Spectra ofInvariant Mass Spectra of

0SK p KK

2

0

MeV/c1.9

0.1S/B

000.51

0

SK

SK

2MeV/c4.2

3.0S/B

000.145

2MeV/c2.6

1.1S/B

168

and, 0SK

23.01.2009 ConferenceP.Salabura

KK00-Nucleon Potential-Nucleon Potential

Kaon-Nucleon Potential: 30 MeV @ =0

(HADES and IQMD)

C. Hartnack, J. Aichelin, H. Oeschler

Results from FOPI (HSD)

KN-Potential is repulsive with a strength of U=20 MeV

23.01.2009 ConferenceP.Salabura

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p+p @ 1.25 GeV - p+p @ 1.25 GeV - Dalitz decay Dalitz decay

Dalitz decaye++

e--

p

e--

Time-like - N transition branching ratio BR(M) ?

EM-formfactors (GM , GE, GC)?

q2 = M2inv(e+e-) = M*

2 > 0

*

grey band Iachello. VMD

QED

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)

PRELIMINARY

22

2

2

2222

232, qqq

Δf G

mq

GGqm C

Δ

EM2

-

dq

)eNe(Δd

VMD

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d+pd+pppspecspec e+e-X @ 1.25 AGeV – e+e-X @ 1.25 AGeV –

„quasifree” p-n collisions„quasifree” p-n collisions

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

neutron „target” proton

protonneutron

e+ e–

PRELIMINARYpspec

pc

No satisfactory description of pp and pn data!!

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22

log. z axis !

e-

e+

hadron : lepton suppression ~10-4

Particle IDentificationParticle IDentification

ee--

ee++

pp 21)2/sin(2 Minv =

p

1 p

2TargetTarget

RICH

HADRONS

Momentum vs velocity (Momentum vs velocity (ββ))

dE/dx in MDC & TOFdE/dx in MDC & TOF

LEPTONS(RICH tagging)(RICH tagging)

Kaon identification

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