Probing resonance matter with HADES „” „EMMI Workshop and XXVI Max Born Symposium” Wrocław Wrocław P. Salabura Jagiellonian University/GSI for the HADES collaboration

Baryonic matter at 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(π 0 )~10% “resonance matter” 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) ~10fm/c Composition of a barionic matter Rear probes: dielectrons & strangeness HADES

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

Reference: dielectrons from pp and “quasi-free” 1.25 AGeV  pp/pn data are not described by recent OBE calculations ! 12 Model Calculations: a) NN  NNe+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) VMD form- factor (Q. Wan and F. Iachello, Int. J. Mod. Phys. A 20 (2005) 1846)

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 A part )-first evidence for the in-medium effect – baryonic radiation : i.e  N  N N   N  .. (  fireball ~10x   ) !  Different mechanism as at SPS ( pion annihilation) preliminary F ~ 3

Vector mesons  /  at SIS p+p at 3.5 GeV    Ar+ 38 KCl 1.75 AGeVp+ 92 Nb 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/c 2 preliminary 

K + K - /  - production at SIS via  ? Strangeness Exchange : belived to be dominant non-resonant resonant (  ->K + K - ) 19 sub-threshold, OZI suppressed ?  - (1321) S=- 2 deep subthreshold (~600 MeV) not measured Strangeness Exchange + network of reactions  sensitvity to EOS A.Andronic, P. Braun-Munzinger, B. K. Redlich, NPA 765 (2006) SIS?

 /  Production in 1.75AGeV  /  Production in 1.75AGeV   /  ~1 fixed to pp data,  yield in line with m T 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/c 2  = 6.2 MeV/c 2  e+e-  e+e-   =23  6 MeV OZI preliminary S. Wheaton and J. Cleymans, hep-ph/

 / K - ratio Statistical model K. Redlich, H. Oeschler-priv.comm T eff =69  3 T eff =89  4   /K - =0.34  0.13 &  is enhanced  is important source of K - in HI collisions at SIS HADES: accepted PRC: arXiv: T eff =84  8

 - production in 1.75 AGeV P.Salabura identification: HADES data THERMUS fit S. Wheaton and J. Cleymans, hep-ph/ ? T= 70  3  b =746  15 (MeV) R C =2.6  0.4 fm R fireball =6  0.7 fm  2 =2.1 (no  - ) preliminary

Outlook: future exp. Upgrade RPC, DAQ, MDC1, EM Calorimeter (for SIS100) 2008/9/10 Hades goes to FAIR ( 8 AGeV) > 2013 (SIS100) 2011  + N,  + A resonance ( , N * ) radiative decays, strangeness 2010 Ag Au+Au dielectrons (  /  ), strangeness (K - K + . ,  ) SIS18 increase of Mul(  /  ) by 2 orders of magnitue !! CBM HADES

P.Salaura12 The Collaboration GSI SIS  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

P.Salabura BACK-UP SLIDES Conference

Side View START FW 3 High Acceptance Di-Electron 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, , , Geometry Full azimuth, polar angles 18  - 85  e+e- pair acceptance  0.35 ~ channels, segmented solid or LH 2 targets 1 m P.Salabura

P.Salabura N-N Bremsstrahlung E.L. Bratkovskaya and W. Cassing arXiv: v1 NN ("quasielastic")-non resonant Strong + electromagnetic process (OBE models) 1 2 e+ e- + = resonant -baryon resonances (  ) 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- Invariant 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 cocktail HADES data 3.5 GeV compared to model calc. GeV 00    // P.Salabura

P.Salabura 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) Conference

Invariant Mass Spectra of ConferenceP.Salabura

K0-Nucleon Potential Kaon-Nucleon Potential: 30  =  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 ConferenceP.Salabura

GeV -  Dalitz decay  Dalitz decay e+e+ ++ e--e-- p e--e-- Time-like  - N transition  branching ratio BR(M) ?  EM-formfactors (G M, G E, G C ) ? q 2 = M 2 inv (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) VMD form-factor (Q. Wan and F. Iachello, Int. J. Mod. Phys. A 20 (2005) 1846) PRELIMINARY VMD P.Salabura

21 d+p  p spec 1.25 AGeV – „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 proton neutron e + e – PRELIMINARY p spec pcpc No satisfactory description of pp and pn data!! P.Salabura

22 log. z axis ! e-e- e+e+ hadron : lepton suppression ~10 -4 Particle IDentification e-e-e-e- e+e+e+e+  M inv = p1p1 p2p2 Target RICH HADRONS Momentum vs velocity (β) dE/dx in MDC & TOF LEPTONS (RICH tagging) Kaon identification P.Salabura