html5-img
1 / 26

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.

whitley
Download Presentation

HADES experiments investigating in- medium hadron properties

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related