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Recent HADES results

Recent HADES results. P. Salabura M. Smoluchowski Institute of Physcis Jagiellonian University. HADES 2010-2013 results. e+e- production in p+p, p+A @ 3.5 GeV Vector meson and  in (cold) nuclear matter Baryon Resonance decays

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Recent HADES results

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  1. Recent HADES results P. Salabura M. Smoluchowski Institute of Physcis Jagiellonian University

  2. HADES 2010-2013 results • e+e- production in p+p, p+A @ 3.5 GeV • Vector meson and  in (cold) nuclear matter • Baryon Resonance decays • e+e- production in HI collisions: status of Au+Au data

  3. e+e-sourcesat SIS18 energies excitation function ! isospin effects Ebeam < 2 AGeV ° e+e- e+e-  HADES PRC85 (2012) 054005 e+e- DLS: PRC57 (1998)1867 ,  Ne+e- 1 2 3 4 5 Ebeam (GeV)  Me+e->M0 • Me+e- < 0.15 GeV/c2 dominated by 0 Dalitz • 0.15 < Me+e- < 0.55 GeV/c2 : Resonance (, N*)Ne+e- (Dalitz decays) • NN-bremmstrahlung, and  e+e- decays ! • M > 0.55 GeV/c2 : Resonance (, N* ) Dalitz decays + / ~2 Understanding of Baryon Sources is essential for HADES physics

  4. Inclusive e+e- productioninpp @ 2.2 and 3.5 GeV 3. 5 GeV 2.2 GeV HADES EPJA48 (2012) 64 HADES PRC85 (2012) 054005 • Unexplained yield excess above exp. cocktail below VM pole • At 3.5 GeV : • 0 Dalitz decay fixed by data • and resonance (, N* ) not easy to isolate ! higher resonances? • / fixed to some extent by exclusive pp data (hadronic channels) and clear  peak

  5. e+e- pTdistributions p+p @ 3.5 GeV sensitive to / contributions !

  6. p+pvsp+Nb @ 3.5 GeV data: HADES PLB715 (2012) 304 „fast” pe+e->0.8 GeV/c „fast” pe+e-< 0.8 GeV/c Nuclear modification factor pp data scaled by „Apart” scaling • large acceptance at small Me+e- and p (<1 GeV/c) ( first measurement at low p !) • for slow e+e- : excess emerges above pp reference ,  peak less pronounced

  7. RapiditydistributionsppvspNb @ 3.5 GeV p+Nb:clear shift towards target rapidity for M>M

  8. e+e- excessinp+Nb : lowpe+e- „slow” (p<0.8 GeV/c) pairs „excess over pp reference” Rpa vs momentum Me+e • RpA (vs p) – increase at small momenta : largest for the „-region” BUT NOT for  peak   absorption (observed also by CBTAPS and CLAS in (+A) ) ! • clear excess in p+A below VM pole  • - secondary reactions : +N   (1720,..)(N* (1520),..) NNe+e- (see J. Weil talk) • or/and in medium  modification ? first the p+p reference must be understood !

  9. 0 /  productioninp+Nb @ 3.5 GeVwithconversionmethod HADES (2013) arXiv:1305.3118 mT scaling of light mesons Total detection probability 10-6 -10-7 ! Similar analysis for p+p in progress!

  10. 0/ pTdistribution/yieldscompared to transport EXP (4): 0 

  11. e+e- sourcesinpp @ 3.5 GeV J.Weil: EPJA48 (2012)111 E. Bratkovskaya et. al.: arXiv:1301.0786v1 • Many uncertainties: inclusive cross sections , ,  , / (fixed now by HADES) • pe+e- transition (Dalitz decay); rates, em. Transition Form-Factors •  - spectral function !

  12. Ne+e-Dalitzdecay QCD QED • „point-like” N e- e + • exact field theory calculation • 3 independent amplitudes: • e.g. Electric, Magnetic and Coulomb electromagnetic form factors GM(q2),GE(q2),GC(q2) spin flip „pion cloud” e+ I.G. Aznauryan andV.D. Burkert, Prog. Part. Nucl. Phys.67 (2012) q „quark core” q q e- « Photon point » : q2=0 GM(0)=3, GE(0)=GC(0)~0 Jones and Scadron convention

  13. Ne+e- : twocomponent (pion cloud+quarkcore) models Iachello, Wan: implemented for HADES by I. Froehlich et. EPJA 45, 401 (2010) M. Pena, G. Ramahlo PRD85 (2012) 113014 cloud/core ~ 0.99/0.01 cloud/core ~ 0.44/0.56 M=1.8 QED QED M=1.5 M=1.23 Mee [GeV/c2] • pion cloud /core contribution affects strongly Q2 dependence of eTFF  VDM • T. Pena - higher resonances in work..

  14. Higherresonances.. QED: point-like R-* vertex M. Zetenyi et al. PRC 67, 044002 (2003) constraints from R->N Resonance model GiBUU, UrQMD, BUU,HSD .. extended VDM: M. I. Krivoruchenko et al. Ann. Phys. 296, 299 (2002). example:J. Weil EPJA 48(2012)111 „factorization” eTFF (Mee)

  15. Baryonresonacesin p+p@3.5 GeV • Goal: Study 3 connected exclusive channels: • pppp0and pppn+ to fix R (,N*) cross sections • Convert Rpe+e- and check in pp pp e+e- • Resonance model: production amplitude is given by incoherent sum • of Resonance contributions, isospin relations • Starting point: S. Teis R parametrization (S. Teis et al., Z. Phys. A356, 421 (1997).) , take 4* resonances + empirical angular distributions (strong forward-backward peaking) BR(Rpe+e-) : „QED” point-like R-* vertex M. Zetenyi and Gy. Wolf., Heavy Ion Phys. 17 (2003) 27. For the overlaping resonances only one resonance with largest BR(N) selected

  16. One pion production A.Dybczak phd Kraków (2013) pn+ • Acceptance corrected spectra • ++ (1232) dominates ! • excelent description of -line shape („Moniz” FF) pp0 • +(1232), N*(1440),N*(1520),.. P.Salabura

  17. exclusive / productioninpp @ 3.5 GeV K.Teilab phd Frankfur (2011) = = N* (1535) fixed from  Dalitz plot N* (1535) ->p BR(42%) N*(1535) = 1520.15 [mb]

  18. Results for ppe+e- channel „QED” : point like RN* vertex • Significant contribution from higher (than ) mass resonances • Addtional strength below VM pole needed – off shell  meson coupling ! – extended interaction vertex • low mass resonances : (1232), N(1440), N(1520) ?

  19. eVDM and (1232) eTFF eTFF from Iachello, Wan saturates the yield- no place left for other resonances • large ambiguities related to the resonance selection

  20. Comparison to otherparametrizations comparison to UrQMD: S. Bass Prog.Part.Nucl.Phys. 41 (1998) 225-370 comparison to S. Teis Preliminary J. Weil et al. EPJA 48(2012)111 Resonances with BR(N)

  21. RNNe+e- Resonance XS and RN BR from UrQMD Resonance XS and RN BR from GiBUU Preliminary

  22. e+e- from HI collisions

  23. e+e- pairsfromAr+KCl @ 1.756 Cocktail with „freeze-out” comp.  component subtracted data PRC84(2001)014902 • first ->e+e- observation at SIS18 energies • first evidence for „true” excess above NN and light CC systems • Excess yield scales with system size ~ Apart1.4  multistep processes? • let’s see Au+Au !

  24. Au+Au May’2012 • New RPC detector (180 << 450 ) • New DAQ and read-out – 10 kHz data taking rate

  25. Strangenessreconstruction

  26. Lepton ID and purity Single lepton purity PID: Multi-Variante Analysis Vertex reconstruction electrons hadrons

  27. Summary • Precise e+e- data collected for pp/pNb @ 3.5 GeV evidences for interesting physics („excess” below VM pole) • Intepretation is challanging ! - pp reference net (yet) well understood exclusive ppe+e-, pp0 , pn+ show that off-shell -R coupling in R-> pe+e- isvery important -  inclusive production is possible with conversion technique ! IT IS IMPORTANT REFERENCE system for HADES at FAIR • HADES made succefull Au+Au @1.23 GeV campaign • single track and resonance (hadron) reconstruction shows great data quality • e+e- spectra are very close to be produced

  28. SIS The HADES collaboration 13 Institutions Technical Proposal accepted 1995 First experiments 2001 • Cracow (Univ.), Poland • Darmstadt (GSI), Germany • Dresden (FZD), Germany • Dubna (JINR), Russia • Frankfurt (Univ.), Germany • Giessen (Univ.), Germany • München (TUM), Germany • Moscow (ITEP,RAS), Russia • Nicosia (Univ.), Cyprus • Orsay (IPN), France • Rez (CAS, NPI), Czech Rep. • Sant. de Compostela (Univ.), Spain • LIP, Portugal GSI P.Salabura

  29. Study of hadron properties in dense baryonic matter • The case of Large B and moderate T : • interesting region in phase diagramme with a large discovery potential • not probed experimentally by means of rare penetrating probes L. McLerran, R.D. Pisarski 2007 • Probes: • dielectrons : • sensitive probe of extended baryon structure -medium modifications ? • meson in medium properies • Multistrange baryons: -(1321),  • Strategy: • Systematic measurements • in p +p, p+A and A+A at 2- 8 AGeV RHIC, BES Na61 experiment: chemical freeze-out VDM CBM Fair Begun et. al. arXiv:1208.410 HADES

  30. ResonancepropertiesUrQMD S. Bass Prog.Part.Nucl.Phys. 41 (1998) 225-370 P.Salabura

  31. N R g* e+ r, w, e- Baryonresonancestructure Time-Like el.Transition Form Factors : Dalitz decays Space-Like el.Transition Form Factors n - e- R q2 <0 p * e+ * R p q2 > 0 e- e- 0 e-- p Vector Dominance Model studied at JLab/CLAS/MAMI,.. pion electroproduction Dalitz Decays: poorly known !  directly related to : e+e-NNe+e- Dalitz decays , e-pe-N  Time Like domain : q2 >0 Space Like domain q2 <0 0 q2

  32. e+e- fromC+Ccollisions and NN  contribution subtracted cocktail: „long lived sources”-freeze out data: HADES PLB690 (2010)118 baryons PRL98(2007) 052302 ratio CC/NN • NN=1/2(np+pp) –reference- and C+C normalized to the individual N(0 )=1/2(N(+) + N(-)) • e+e- subtracted („long lived” source) - cross section known from other exp.( TAPS) • C+C data (1 and 2 AGeV !) reproduced (within 20%) by NN reference up to 0.45 GeV/c2 – no room (within error bars) for in-medium effects

  33. ExcessscalingwithApart/Ebeam C+C Ca+Ca TAPS - HADES, DLS e+e- • Baryonic sources : (1232) ~10-20%, N(1535,..)- 1-2%, N–N bremsstr.. • excitation function similar in shape to pions

  34. pspec pt Quasi freep+nreactionwithdeutron d spectator model X p n • average pn distance ~ 3 fm • total cross section reduced by ~8% • (p shadowing + meson absorption) Ek=1.25 AGeV momentum in deuteron rest frame

  35. pspec pt Quasi-free pn reactionsind+pcollisions spectator model d X=, , .. p n spectator on-shell CELSIUS: PRC58(1998)2667 Ed=0.76 GeV Ep=1.35 GeV COSY-TOF EPJA29(2006) 353

  36. Spectator model atwork (Q<100 MeV) p+d -> ps pn  d+p -> ps pp- p+d -> ps d COSY11, SATURNE, CELSIUS P. Moskal, nucl–ex/0110001 and P. Moskal PRC79(2009) 015208 COSY-TOF EPJ. A 29, (2006) 353 ANKE PRL 97 (2006)142301 pspectator momentum MC ( NN pot) • overall good agreement with spec. model p+d -> ns pp

  37. exclusive channel: np.npe+e- Exclusive (e+e-) - one proton e+e- in HADES ppe+e- npe+e- • excess in np reaction visible also in exclusive channels (note: no  contribution! ) • missing mass spectra reproduced by simulation ppppe+e- npnpe+e- Me+e- >M0 Me+e- >M0

  38. Inclusive e+e- (n+p)QFvspp calculations: R. Shyam and U. Mosel Phys. Rev. C 82:062201, 2010 data: HADES PLB690 (2010)118 • excess np. over pp ! • R. Shyam and U. Mosel Phys. Rev. C 82:062201, 2010 • due to eFF of charged pion • charge pion exchange & pion eFormFactor pion eTFF : W. Weise, G. Brown, M. Rho NPA 474(1986)669 p p n p e+ π0 ρ π+ ρ e+ e- e- π0 π- p p n p

  39. e+e- inp+p @ 1.25 GeV inclusive Mainsource: pe+e- Dalitz decay  production not possible – belowthreshold  GM (q2) VMD Time Like (q2 >0)  (J=3/2)->N (J=1/2) * transition: Calculations: Vector Meson Dominance Krivoruchenko et al. PRD 65 (2001) 017502 G. Ramalho and T. Pena arxiv: 1205.2575v1 (2012) F. Dohrmann et al., Eur. Phys. J. A 45, 401 (2010) HADES: PLB690 (2010)118 p p • 0 ,  fixed by 1 pion exclusive production : HADES EPJA48(2012) 74 • BR (Ne+e-)  4*10-5 agrees with model predictions. • G(q2 ) dependence not very essential at this low energy.. p p D+ * e+

  40. „Emissivity” of baryonicmatter Dense matter : 3*B ~ 0.5/fm3 30% baryon resonances 33 pions (T~ 80 MeV) e+ Vacumm e- RNe+e- pion cloud e+ e+ e+ q q q q q q q q q e+ q q q q q q q q q q q q q q q q q q - e- e- e- e- qq - qq How does the radiation from overlaping baryons looks like?

  41. in-medium width Transparencyratioin „coldmatter” • „disapearance of meson in nuclear matter” Glauber Picture; CabreraNPA733(2004)130 Production AbsorptionFSI of decay products • ISI (not for ), Pauli-blocking, Fermi-motion, secondary processes, shadowing …. • normalization to C to • reduce nuclear effects absent for e+e-

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