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HADES experiments investigating in- medium hadron properties

HADES experiments investigating in- medium hadron properties. P. Salabura Jagiellonian University for the HADES collaboration. . K -. K +. Study of hadron properties in dense and hot nuclear matter.

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HADES experiments investigating in- medium hadron properties

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  1. HADES experimentsinvestigatingin-medium hadron properties P. Salabura Jagiellonian University for the HADES collaboration

  2. K- K+ Study of hadron properties in dense and hot nuclear matter • Goal: to cover interesting and not fully covered region of baryonic matter at low T • „emissivity” of compressed matter • hadron properties in matter L. McLerran, R.D. Pisarski 2007 e+ e- e+ e- e+ e- • Rear Probes: • dielectrons penetrating probes emissivity and in medium hadron masses : vector mesons (/e+e-) chiral sym. • strangeness production : , K , (1321) EOS, K in-medium potentials, … • Strategy: • Reference measurements in N +N • and A+A at 1-2 AGeV (<2015) and • in future at SIS100 8-10 AGeV (FAIR) experiment: chemical freeze-out RHIC BES Na61 CBM Fair HADES @ FAIR HADES

  3. Side View START FW High Acceptance Di-Electron Spectrometer • Beams from SIS18: protons, nuclei , pions • Spectrometer with high invariant mass resolution - 2% at / • Versatile detector for rear probes : • dielectrons (e+,e-) • strangeness: , K,0 , - • Upgrade(2010): new DAQ (20 KHz, Tof-RPC (tof ~80 ps) RPC (from 2010) 1 m GeometryFull azimuth, polar angles 18 - 85e+e- pair acceptance  0.35~ 80.000 channels, segmented solid or LH2 targets

  4. HADES programme (so far) • e+e- production in N+N – reference reactions for A+A • single and double  production (barion resonances in N+N) • , ,  production- hadr.channels and rear e+e- decays (new UL in PDG) •  (1405) , (1385) (new PDG entry) • K0 production • pp reactions • (1.25, 2.2, 3.5 GeV) • dp reactions (1.25 GeV) • nucleus + nucleus • C+C, Ar+KCl • Au+Au (2012) • p + nucleus • (Nb @ 3.5 GeV) • low mas e+e- „excess” : (DLS puzzle, emissivity,..) • kaon production : K0s • Hyperon production; ,  ,  (1321) •  production • -p, p-p,  , correlations • /mesons in cold nuclear matter • strangeness production K, 

  5. Low mass e+e- excess : „DLS puzzle” before HADES (< 2008) HADES data projected in DLS acceptance DLS data:R.J. Porter et al.: PRL. 79 (1997) 1229 Calculation:E.L.Bratkovskaya et al.PLB445 (1999) 265 HADES data: Agakishiev et al., PLB 663 (2008) 43 • HADES fully confirms DLS results • What about „excess” ? Is it true in-medium effect ? or not understood elementary process?

  6. N+Nreference (I): e+e- inp+p Importantsource: pe+e- Dalitz decay e+ HADES: PLB690 (2010)118 e- pion cloud e+ e+e- pe+e- q q q GM (q2) VMD Time Like (q2 >0)  (J=3/2)->N (J=1/2) * transition: e- 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) p p p p D+ * e+ G(q2 ) ? el. Transition Form Factors : extented baryon structure ! complemenary to  (space like) N  ( data: JLAB/Mainz/Bates)

  7. N+Nreference (II): e+e- inn+p Large isospin effect at 1-2 AGeV! calculations: R. Shyam and U. Mosel Phys. Rev. C 82:062201, 2010 data: HADES e+e- yield ratio dp/pp •  production – fixed by COSY, WASA data • bremsstrahlung pnpne+e- (non resonant), why it is so much different from pp? • R. Shyam and U. Mosel Phys. Rev. C 82:062201, 2010 • charge pion exchange & pion eFormFactor  DLS p n ~2 for example: + n p

  8. CC compared to NN reference.  contribution subtracted cocktail: „long lived sources”-freeze out data: HADES PLB690 (2010)118 baryons PRL98(2007) 052302 ratio CC/NN • NN and C+C normalized to the individual N(0 ) • C+C data (1 and 2 AGeV !) reproduced (within 20%) by superposition of NN interactions (reference) – no room (within error bars) for in-medium effects

  9. Vectormesonsin medium- motivation hadronic many body interactions- spectral functions.. how it begun.. prefered by data • - meson at • 2 x N SPS S. Leupold et al. NPA 741 (2004) 81, NPA 780 (2006) 187 g,p-,p - beams RHIC LHC SIS 18 G.E. Brown / M. Rho: Scaling of masses with c-condensate (PRL 1989, 1991) T. Hatsuda / S. Lee: QCD sum rulesPRC46(1992)R34 SIS 200 T [MeV] 300 Data : Na60 EPJC 59 (2009) 607 calculations: Hess/Rapp: NPA806(2008)339. • second graph is related to elementary process: Dalitz decay

  10. Vectormesonsincoldmatter- experiments direct :  meson line shape KEK-E325 PRL 96 (2006) 092301 CLASPRL 99 (2007) 262302 p+Cu 12 GeV +A 1.1-3.3 GeV   217 MeV •  mass shift • m*/m0 = • 1 – 0.09N/ 0 • no mass shift •  broadenning indirect: transparency  absorption • large  absorption  • *tot,  210 MeV ! •  meson (SPRING8, ANKE) • * ~ 33 - 50 MeV CLAS: PRL 105 (2010) 0112301 CBTAPS: PRL 100 (2008)192302 * N v VN

  11. p+pvsp+Nb @ 3.5 GeV data: arXiv:1205.1918 submitted to PRL „fast” pe+e->0.8 GeV/c „fast” pe+e-< 0.8 GeV/c pp data scaled by „Apart” scaling Nuclear modification factor • large acceptance at small Me+e- and p (<1 GeV/c) ( first measurement at low p !) • p+p cockail : based on known sources fixed to data 0 // /  ,  with constant eTFF • underestimeted e+e- yield below VM pole  missing component? -> higher resonances (, N*)

  12. Fixingresonancecontribution : exclusivechannelsinp+p @ 3.5 GeV pn+ pp0 …many differential distribution studied for pp0 , pn+, pp, pp Preliminary ppe+ e- • RNe+e- constant eTFF • M. Zetenyi et. al. Heavy Ion Phys. 17 (2003) 27 • no off shell coupling to VM assumed •  lower limit for e+e- emission •  / from data (hadronic dec.) • missing yield related to low mass resonances and off shell VM !

  13. e+e- excessinp+Nb „slow” (p<0.8 GeV/c) pairs „excess over pp reference” Rpa vs momentum Me+e • clear excess in p+A below VM pole  • - secondary reactions : +N   (1720,..)(N* (1520),..) NNe+e- ? • el. TFF important !  constraint from ppe+e- …… work in progress • in medium  modification ? answer only after understanding of the p+p reference • RpA (vs p) – increase at small momenta : largest for the „-region” BUT NOT for  peak  strong  absorption consistent with CBTAPS (+A) results!

  14. 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 • Excess yield scales with system size ~ Apart1.4  multistep processes?

  15. Transport model resultsfor Ar+KCl GiBUU: J. Weil at al., arXiv:1106.1344v1 E.L. Bratkovskaya, W. Cassing, NPA 807(2008) 214 • Transport models: not consistent picture • don’t describe (yet) pn data • „excess” region dominated by  but different predictions ! • Me+e->0.60  dominates complicated vacumm structure ! • Are in-medium effects needed? Not clear yet… systematic studies needed newAu +Au data are essential!

  16.  and /ratioin Ar + KCl R/A+A >> R/ in NN and πN reactions   K+K-  e+e- w.r.t N-N threshold •  meson plays important role (~18%) in K- production at SIS18 energies • Statistical model describe  rates with no suppression (i.e OZI rules) ! • R/A+A : enhanced  production and  absorption?

  17. Double strange- (1321) inAr+KCl data: PRL 103 (2009) 132310 •  production significantly larger then transport model (UrQMD) and statistical model predictions • Note that also  is enhanced and  is not suppressed at all  all have ss(bar) content ! SHM: S. Wheaton, J. Cleymans, Comp. Phys. Comm. 180 (2009) 84 data: EPJA 47 (2011) 21 640 MeV below NN threshold ! ..to be continued with Ag+Ag P.Salabura

  18. L(1405) K- K- N-1 Kaonsinnuclearmatter K- in medium: more complicated  spectral function Acta Phys. Hung. A22 2005 21 G.E Brown et.alNPA 567 (1994) 937, T. Waas, e al. PLB 379 (1996) 34 J. Schaffner-Bielich, et al.. NPA 625 (1997),.. indirect measurements : • K+/K0 considered as good quasiparticle • at SIS K+  5 fm (weak absorption) • repulsion from spectator matter : • flow out of plane (KAOS data PRL.95 (2005) 012301,FOPI-> Y. Leifels talks this afternoon) • reduced yield at low pt (p): ( FOPI, ANKE data PRL102(2009)183591) • (1405) physics : entry to K- in medium • properties , kaonic clusters ppK- .., kaonic atoms,..

  19. K0s in medium potential and  (1405) K0s in Ar+KCl @ 1.756 GeV (1405) –bound K- N system? data: PRC 82 (2010) 044907 Preliminary IQMD : repulsive UKN 38 MeV (1405) pole • new data will come from p+A • ..and Au+Au (+ flow measurement) • pole shift? intereference with non. res  ? importnat bench mark for theory

  20. Au+Au run (finished 3 weeks ago) at 1.23 AGeV on line PID vertex reconstruction • Thank to essential HADES upgrade (DAQ,MDC,RPC_TOF) • Ready for campaigns at FAIR SIS100!

  21. Summary: • Low mass pair production in light systems (C+C) explained by known 0  cross sections and baryonic sources fixed from the NN reference reactions: pn- bremsstrahlung +  Dalitz are the essential e+ e- sources explaining „DLS” puzzle • OBE models come closer to pp/pn data : further studies are on-going • for larger systems , Ar+KCl, evidence for onset of pair excess over NN reference : radiation from „resonance (, N*) matter”: New Au+Au data are of key importance ! • in-medium effects on  (A+A and p+A) are not clear yet : determination of  -meson shape in N-N collisions (vacumm) is far from trivial and requires better understanding of /N* - couplings  el.Transition Form Factors , work is in progress • absorption of  and enhanced  production in nuclear matter can be explain large R / • new K0S data support repulsive KN in-medium potential ; (1405) is crucial for antykaon properties in nuclear matter • Large production yields (above SHM predictions) of double strange (1321)

  22. Outlook: 2012-2013 - HI collisions (Au+Au/Ag+Ag) at SIS18 with upgraded HADES continuation of dielectrons + strangeness programme (also K+,K- , e+e-, flow measurements) > in discussion: pion beams : el.TFF of baryon resonances, pion, strangeness production >2016 - HADES at FAIR (SIS100) - zero day experiment- part of CBM physics programme CBM HADES stay tuned: lot of new interesting results are expected !

  23. SIS The Collaboration • 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

  24. Gross properties of the baryonic matter S.Vogel et al. (URQMD) arXiv:0710.4463v2 • 1-2 AGeV : moderate densitiesbut long system lifetime • Baryonic matter: • /N = 1-3, T< 80 MeV,  ~12-14 fm/c nucleons, baryonic resonances (~30%) 33 mesons(π0) ~10%“resonance (, N*) matter” Au+Au • Sub-threshold production of (, , K- K+, ) : • confined to high density zone • Multi-step processes ~ Apart>1 ex:  production SPS AGS N+N->N , +NN +N +  Rapp & WambachAdv. Nucl. Phys. 25(2000) SIS  P/ e+e-  10-6 ! K+ / K-

  25. Upcomingexperiments : Au+Au and Ag+Ag (2010-2012) simulation: 4 weeks of beam (no in-medium effects included) counts ½(pp+pn) • maximum excess (intermdediate mass) • High statistics differential studies of excess centrality, dN/dmt , angular distributions • Ag+Ag : maximal density  VM (/) production rate at SIS18 • High stat. spectroscopy of VM region • Strangeness programme

  26. Resonancereconstructionstrangeness Ar + KCl @ 1.75 AGeV: excellent rec. capabilities K0s ->+ + -  ->p+- ->+-  ->K+ + K- first observation at SIS GeV/c2

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