The physics of dense baryonic matter: From HADES to CBM DM2010 International Workshop on High Density Matter STIAS, Stellenbosch, South Africa Joachim Stroth, Goethe-University Frankfurt / GSI

Agenda o Introduction o Dileptons from light collision systems o Vector meson production o Strangeness production o The future at SIS18, SIS100 and SIS300 o Summary

The HADES GSI

The HADES Mission Phase 1 ( ) -> Upgrade – Light collision systems (limited granularity of TOF system) Phase 2 (2010 – 2015) – Heavy collision systems,  -induced reactions Phase 3 (FAIR/SIS100) – Excitation function up to 10 GeV/u (medium-heavy systems) Search (in this region) for medium-effects partial restoration of chiral symmetry onset of decofinement  Beam energies of 1-2 GeV/u

   p - beams SIS 18 SIS 200 T [MeV] 300 LHC RHIC SPS Partial restoration of chiral symmetry From vector manifestation of hidden local symmetry: “... to suggest that the dileptons measured in relativistic heavy-ion collisions do not provide direct information on the spontaneous breaking of chiral symmetry and hence on the mechanism for mass generation of light-quark hadrons.” Brown, Harada et al. Prog.Theor.Phys.121: ,2009 W. Weise et al. + BR scaling (PRL 1991) R. Pisarski, L. McLerran et al.

HADES run statistics (phase 1) p+Nb Ar+KCl 1.67GeV/u pp 3.5 C+C 2 GeV/u dp 1.25 GeV/u pp 1.25 GeV/u C+C 1 GeV/u o 6 runs between 2002 and 2008 o events taken o 100 days beam on target After upgrade in 2010: TByte in 30 days FW  > 7 o Eur.Phys.J.A41: ,2009

Dileptons from light collision systems

Electron pairs from C+C collisions at 1 and 2 GeV/u Phys.Rev. Lett 98(2007) Phys. Lett. B 663 (2008) 43  Good normalization established in  0 region.  Evidence for yield above contributions from decays of long-lived hadrons.  What are the sources of contributions from the early phase? e+e+ e-e- ** ** e+e+ e-e- ** e+e+ e-e-

The solution to the DLS puzzle? HADES data in the acceptance of DLS, compared to DLS data. E. Bratkovskaya et al., PLB Modified description of Bremsstrahlung in HSD inspired by Kaptari et al.

Dileptons from pp and np reactions at 1.25 GeV/u compared to HSD Data from HADES pp and dp (tagged n) at 1.25 GeV/u Cocktail from HSD calculation 2008 with revised description of Bremsstrahlung Data: HADES collaboration, arXiv: [nucl-ex]

Electron pairs from C+C collisions compared to NN reference HADES collaboration, arXiv: [nucl-ex] N N N N  N *, Δ N N N N  N N N N  

Dileptons from Ar+KCl at 1.76 GeV/u

Electron pairs from Ar+KCl collisions at 1.76 GeV/u First observation of  mesons in HI collisions at these (SIS) energies HADES collaboration, Nucl.Phys.A830:483C-486C,2009 Fit: exponential + gaussian counts In peak!

Excess radiation in Ar+KCl at 1.67 GeV/u Compared to reference after subtraction of contributions from   Indication for radiation from the medium.  Multistep processes or multi-particle correlation. R R  N N  N N N N  R e-e- e+e+ N N

Excess yield scales stronger than linear with A part Data for  0 and  from TAPS collaboration Dilepton excess scales with beam energy like  production C+C (DLS) C+C (HADES) Ca+Ca (DLS) Ar+KCl (HADES) Systematic of the excess yield

Refined HSD vacuum calculation o Enhanced bremsstrahlung from elastic NN collisions according to “Kaptari-Kämpfer” (OBE) prescription. o Reduced vector-meson production via the LUND string in order to better match pp exp. Data. o Improved isospin dependence of the channels NN-> V+NN and  +N-> V+N. HSD, November 2009 release “It’s a bingo”

17 Dileptons from pp at 3.5 GeV HSD, Nov. 09 release K. Schmidt, et al. Phys. Rev. C 79, (2009) Normalized to π peak

Dilepton production in pp at 3.5 GeV Particle production LUND string fragmentation Particle production through baryonic resonances

Slope parameters in mass bins M ee = 0.35 – – 0.65 >0.65 GeV Strong increase of slope parameter with increasing pair mass. No explanation yet.

strangeness

Strangeness production in 1.75 GeV/u Ar+KCl reactions Λ 0s0s -- High-statistics measurement of       and   but also:  0 s →      → p  -  →      - →   - HADES collaboration: Phys.Rev.Lett.103:132301,2009 Eur.Phys.J.A40:45-59,2009 Phys.Rev.C80:025209,2009

HADES data and the SHM Particle multiplicities largely in accordance with SHM o  yield explained (non-strange particle ) o  − underestimated by SM ■ Ar+KCl at 1.76 GeV/u THERMUS fit S.Wheaton and J.Cleymans, J.Phys.G31(2005)S1069 T= 73  6  b =770  43 (MeV) R C =2.4  0.8 fm R fireball =4.9  1.4 fm  2 =2.1 (no  - ) J.Cleymans priv. communication

/-ratio M  (→ K + K - ) : (2.6 ± 0.7) ·10 -4 M  (→ e + e - ) : (6.7 ± 2.7) ·10 -3 In accordance with SHM. No OZI suppression in the production.

Multi-strange baryons Probability (M ss ) to produce in Ar+KCl collisions a strange quark pair is ≈ 5 × q q q q q q q q q q q q q q q q q q q q q q q q Bag fusion  quarkyonic matter? Strange quarks “trapped” in bubbles?

The HADES upgrade … … from 8   /day (Ar+KCl) to 170   /day (Ag+Ag) and dilepton statistics like NA60

The RPC time-of-flight system Full-system test results:  t  78 ps  x  8 mm  ~ 97% D. Belver et al. NIM A602(2008) 687, 788 E. Blanco et al. NIM A602(2008) 691 RPC D. Belver et al. NIM A602(2008) 687, 788 E. Blanco et al. NIM A602(2008) 691 Leading institute: Coimbra, Portugal

CTS VME CPU MU... RPC F. Wall MDC RICH Shower VULOM3 Start, Veto TOF Ethernet HADES DAQ System Overview To the Front End Electronics Fröhlich et al., IEEE Trans. Nucl.Sci. Vol. 55, Issue 1 (2008) 59 Average data rate 150 Mbyte/s. Trigger rate up to 20 KHz.

Current proposal (2-3 campaigns). Main emphasis on: Dielectron & strangeness production in heavy systems low mass (0.15<M e+e- <0.5) excess studies vector meson spectroscopy  /K  production: differential distributions, y, p t (increased acceptance due to RPC !), flow  - production characteristics Two HI collision systems : medium size,eg. Ag+Ag, and Au+Au at maximal beam energies of 1.65, 1.25 AGeV, respectively.

The Future at FAIR SIS18 Upgraded HADES (20 kHz reaction rate) Au+Au and Ag+Ag, pion induced reactions from 2010 on. SIS100: Joint running of HADES and preCBM, multistrange particle and lepton pair excitation function, charm production in proton induced reactions SIS300: Full exploitation of rare probes a high  B; fluctuations, flow Mission: Systematics and sensitivity! Phase boundary and critical point.

Towards FAIR

The Quest for the highest densities J. Randrup and J. Cleymans, hep-ph/ Freeze-out configurations for HI collisions! Density in the centre of the collision zone UrQMD

The CBM detector o More than one million reactions / second (no trigger) o Fast high resolution tracking in a compact dipole field directly after the target o High speed DAQ and trigger o Excellent particle identification o Flexible arrangement of PID detectors and calorimeters:

Dilepton production Thermal dilepton rate... isentropic expansion... or from transport In future: combine the best of the two worlds!

Charm production o How are the produced charm quarks propagating in the dense phase, quark-like or (pre-) hadron-like? ◊ Hidden over open charm as indicator (J/ψ, ψ', D 0, D  ) ◊ Charmed baryons important for a complete picture (  c, Ξ c ) ◊ Are there indicators of collectivity [HSD: O. Linnyk et al., Int.J.Mod.Phys.E17, 1367 (2008)] [SHM: A. Andronic et al., Phys. Lett. B 659 (2008) 149]

Charm detection in CBM o Challenge: ◊ Find displaced decay vertex in an environment of hundreds of charged tracks ◊ Event selection:real-time vertex finding in 20Gbyte/s o Needs vertex detector with: ◊ High resolution ◊ Minimal material budget ◊ Radiation tolerance o Monolithic Active Pixel Sensors, also foreseen in ILC, STAR c  = 312  m 35 Diamond 300 µm ~ 60 µm Si < 200 µm Si ~ 60 µm Si < 320 µm Si Factor 4-5 thinner than conventional solution IMEC, Strasbourg, Frankfurt

Summary – „Long-lived“ states of dense nuclear matter are produced in collisions of heavy ion at energies of a few GeV/u. – The phase in the high-density region might be much more exotic then a hadron/resonance gas. – Unfortunately, there is no smoking gun, but: Fast equillibration „Sub-threshold“ production Strong broadening of in-medium states – Close collaboration with, and novel approaches in theory are necessary to make the case.

The HADES collaboration LIP-Laboratório de Instrumentação e Física Experimental de Partículas, Coimbra, Portugal Smoluchowski Institute of Physics, Jagiellonian University of Cracow, Kraków, Poland GSI Helmholtzzentrum für Schwerionenforschunm, Darmstadt, Germany Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany Joint Institute of Nuclear Research, Dubna, Russia Institut für Kernphysik, Johann Wolfgang Goethe-Universität, Frankfurt, Germany II.Physikalisches Institut, Justus Liebig Universität Giessen, Giessen, Germany Institute for Nuclear Research, Russian Academy of Science, Moscow, Russia Physik Department E12 & Excellence Cluster Universe, TUM, München, Germany Department of Physics, University of Cyprus, 1678 Nicosia, Cyprus Institut de Physique Nucléaire (UMR 8608), CNRS/IN2P3 - Université Paris Sud, F Orsay Cedex, France Nuclear Physics Institute, Academy of Sciences of Czech Republic, Rez, Czech Republic Departamento de Física de Partículas, University of Santiago de Compostela, Santiago de C.a, Spain

The CBM collaboration China: Tsinghua Univ., Beijing USTC, Hefei CCNU, Wuhan Croatia: University of Split RBI, Zagreb Czech Republic: Techn. Univ., Prague CAS, Rez France: IPHC Strasbourg Germany: GSI, Darmstadt FZ Dresden-Rossendorf Univ. Heidelberg, Phys. Inst. Univ. HD, Kirchhoff Inst. Univ. Heidelberg, ZITI Univ. of Kashmir, Srinagar Banaras Hindu Univ., Varanasi Korea: Korea Univ. Seoul Pusan National Univ. Norway: University of Bergen Poland: Silesia Univ. Katowice AGH Univ. Krakow Jagiellonian Univ., Krakow Warsaw Univ. Portugal: LIP Coimbra Romania: NIPNE, Bucharest Bucharest University Univ. Frankfurt, IKF Univ. Frankfurt, Inst.Comp.Sc. Univ. Münster Univ. Wuppertal Hungaria: KFKI, Budapest Eötvös Univ. Budapest India: Aligarh Muslim Univ., Aligarh IOP, Bhubaneswar Panjab Univ., Chandigarh Gauhati Univ., Guwahati Univ. of Rajasthan, Jaipur Univ. of Jammu, Jammu IIT, Kharagpur SAHA, Kolkata Univ. of Calcutta, Kolkata VECC, Kolkata Russia: VBLHE, JINR, Dubna LIT, JINR, Dubna LPP, JINR, Dubna PNPI, Gatchina ITEP, Moscow MEPhI, Moscow Kurchatov Inst. Moscow SINP, Moscow State Univ. Obninsk State Univ. IHEP, Protvino KRI, St. Petersburg St. Petersburg Polytec. U. INR Troitzk Ukraine: INR, Kiev Shevchenko Univ., Kiev Split, institutions > 400 members

Thank you

Exclusive electron pair production in pp collisions at 1.25 GeV Three particle missing mass (M X ) pp  pe + e - X 200 events for M e+e- > 140 MeV/c 2 pp  p  +  ppe + e - HADES data M ee >140 MeV/c 2 Preliminary M X (GeV/c 2 ) M ee (GeV/c 2 ) Electron pair invariant missing mass (M ee )

HSD in-medium calculations

Phi to omega ratio... vector manifestation of hidden local symmetry... to suggest that the dileptons measured in relativistic heavy-ion collisions do not provide direct information on the spontaneous breaking of chiral symmetry and hence on the mechanism for mass generation of light-quark hadrons.

XXI HADES Coll. Meet. March Systematics of slopes at 1.76 GeV/u Why are slopes of ρ/ω and  so different ? π 0 and η from TAPS

HADES has a two level trigger system LVL1 trigger Multiplicity 34% more central events of events LVL2 trigger at least one electron candidate GEANT simulation with UrQMD events 2.1× 10 9 triggered LVL1 events in the Ar+KCl run! Trigger

Effenberger, Giessen

Dileptons from pp and np reactions at 1.25 GeV/u PLUTO:   resonance: production: fixed to  0 by N(  ) = 3/2 N(  0 ), decay: Krivoruchenko et al., EM form-factor: QED, Krivoruchenko, G M =3, G E =G C =0 or VMD-like, Wan & Iachello, int. J. Mod. Phys. A20(2005) 1846   meson: constrained by CELSIUS/WASA data, H. Calén et al. PRC 58, 1998  NN Bremsstrahlung: is currently implemented a-lá Kaptari and assuming isotropic emission p+p data : results from OBE (coherent sum of  and NN terms) seems to be too high (already  cross section is too high (factor 2-4), NN Bremsstrahlung also?) n+p data : not explained by theory, clear contribution of additional sources HADES collaboration, arXiv: [nucl-ex]