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Exploring baryon rich QCD matter with HADES and CBM

This presentation discusses the physics case of the HADES experiment, focusing on the exploration of baryon-rich matter in the QCD phase diagram. Topics include hadron production, electromagnetic radiation, collectivity, and rare and penetrating probes.

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Exploring baryon rich QCD matter with HADES and CBM

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  1. Exploring baryon rich QCD matter with HADES and CBM Szymon Harabasz for the HADES Collaboration Introduction Sub-NN-threshold hadron production Electromagneticradiation in vacuum and medium Collectivity Summary

  2. Introduction

  3. What is the QCD phase structure? • Vanishing mB, high T (lattice QCD) • Crossover, universality • no CP indicated by lattice QCD atmB < 400 MeV, T >140 MeV • Large mB moderate T (QCD inspired models) • Thermal equilibrium? • 1st order transition? • QCD critical point? • Melting of the condensate? 2 < √sNN < 8 GeV Large discovery potential! [P. Steinbrecher (HotQCD), arXiv:1807.05607 Condensate: B.J. Schaefer and J. Wambach]

  4. The HADES physicscase • Pion and nucleonbeams: • Reference measurements (vacuum, cold QCD matter) • Electromagneticstructure of baryons and hyperonsin the region of 0 < q2 < 4mp2 • Heavy ioncollisions: • Properties of matteroccuring in neutron star mergers [T. Galatyuk, Nucl. Phys. A982(2019)] CBM Au+Au, GeV NS mergers HADES [Fig. credit: T. Galatyuk, M. Hanauske, F. Seck] • High mB region of QCD phase diagram • Mainfocus on rare and penetratingprobes • Variousaspects of baryon-mesoncoupling T < 70 MeV, r≈3r0 in bothcases

  5. Meet the HADES(High Acceptance Di-ElectronSpectrometer) [HADES Coll., Eur.Phys.J. A54 (2018) 85] Photo: Jan Michael Hosan/HA Hessen Agentur GmbH 4.3⨯109 of 40% most central Au+Aueventsrecorded Beams from SIS18: protons, nuclei,secondary pion beams,Ekin=1-2 GeV/u Fast detector interactionrate: 8 kHz in AuAu, 200 kHz at SIS100 Large acceptancefullazimuth, polar from 18o to 85o Mass resolution of the order of few % Good particle identification Efficient track reconstruction Search for rare and penetrating probes Di-lepton production suppressed by the factor a2 Sub-thresholdproduction of strangeness and vectormesons

  6. Particleidentification performance • By means of: • Velocity and momentum • dE/dx in TOF and MDC • RICH information and PreShower RICH

  7. Sub-NN-Threshold hadron Production

  8. Open strangeness in Au+Au at = 2.4 GeV(below NN productionthreshold) [HADES Collab., arXiv:1812.07304, accepted by PLB] Constrainstrangenessproduction and propagationmechanism

  9. Comparison to microscopic transport [HADES Collab., arXiv:1812.07304, accepted by PLB] • K-N potentialatr0, raisinglinearly with density • The yield of kaons and itscentralitydependencecomecloser to the data • Lisalsoaffecteddue to the associatedproduction

  10. Hadron yields as function of system size [HADES Collab., arXiv:1812.07304, accepted by PLB] • All strangehadronsproducedbelow thefree NN threshold: • K+L: -160 MeV • K+K-: -470 MeV • Universal scaling with participantnumber • Not expectedifenergyaccumulationgoes via isolated NN collisions • "heatbath"

  11. Strangeness in coldnuclearmatter [HADES Collab., arXiv:1812.03728] • Pion beam with p = 1.7 GeV/c • Targets: 12C or184W • K+shifted to backwardrapidity • Rescattering • Absorptiondue to charge exchange isnegligible for K+ but dominating for K- • Significantfproduction • f/K- ratio ~ 0.5

  12. Electromagneticradiation VaCuum and Medium

  13. Exclusiveanalysis of pp→ppe+e- Exclusiveanalysis of pp→ppe+e- [PRC 95, 065205 (2017)] QED: point likeg*NR, Heavy Ion Phys. 17, 27 (2003) I&W: two component quark model, PRC 69, 055204 (2004) R&P: covariantconstituentquark model, PRD 93, 033004 (2016) S&M brems.: PRC 82, 062201 (2010) PDG 2018 First measurement of BR( D→pe+e- ) = 4.19 ± 0.42(model) ± 0.46(syst.) ± 0.34(stat.)

  14. Role of the rmeson 0.9 <Mmissee < 1.03 GeV/c2 Exclusive np→npe+e-, = 2,4 GeV Exclusive p-+p → ne+e-, 1.49 GeV HADES, EPJA 53, 149 (2017) Total ηe+e-γ N(1520)ne+e- Model A [EPJA 50, 107 (2014)], e.g.: Model B [PRC 82, 062201 (2010)], e.g.:

  15. Dilepton excessyield QM 2017 • CoarseGraining (CG): r in-medium spectralfunction with thermodynamicparameters from transport • CG FRA: Phys. Rev. C 92, 014911 (2015) • CG GSI-Texas A&M: Eur. Phys. J. A, 52 5 (2016) 131 • CG SMASH: arXiv:1711.10297 [nucl-th] • HSD: Phys. Rev. C 87, 064907 (2013) Medium radiationgoesbeyondincoherentsuperposition of NN collisions

  16. CollectiVity

  17. Elliptic (v2) azimuthalanisotropyProtons, deuterons, tritons • Comparison of v2 of p, d, tatmid-rapidity • At ourenergies v2 < 0 • "Squeeze-out" ratherthan "flow" • Scaling of v2 and pt with number of nucleons A • Consistent with nucleoncoalescence

  18. Summary and Perspectives • HADES explores baryon rich matter at SIS 18 • Lowest point of variousexcitationfunctions • Indications of thermalized system atmoderate T and high mB • Strangenessproductionconsistent with equilibrium • Thermalcharacterof dilepton spectra • Medium effects in coldnuclearmatter • Evidence on validity of VMD from exclusiceelementarycollisions Outlook • Analysis of moreperipheralevents and Au+C • Look forward to the peaks in Ag+Ag at = 2.55 GeV

  19. Outlook I:Ag+Ag @ 1.58AGeV EXPERIMENT

  20. Ag+Ag @ 1.58AGeV ( 2.55 GeV) • FAIR Phase-0 experiment Event display

  21. Online Reconstruction L → p + p+ Particleidentification Ag+Ag Au+Au Almost no newcallibrationsyet In Ag+Ag 2.55 GeVstrangenessproductionat the threshold

  22. Online Reconstruction K0s → p+ + p- Ag+Ag Au+Au In Ag+Ag 2.55 GeVstrangenessproductionat the threshold

  23. Outlook II:CBM@FAIR

  24. Tetyana Galatyuk | FAIR : CBM | Town Meeting, CERN | 24 Oct 2018 Core Physics Motivation • The QCD Equation-of-State • Search for exotic phases and 1st order phase transition • Is there a Critical point? • Path to restoration of chiral symmetry • Strange matter • Charm production (and propagation) at threshold [CBM Collab., EPJA 53 (2017) 60] Strong interest internationally • RHIC BES, NA61 SPS, MPD NICA (BM@N) • NA60+ SPS, CEE HIAF, HI injector J-PARC

  25. Tetyana Galatyuk | FAIR : CBM | Town Meeting, CERN | 24 Oct 2018 Explore QCD phase structure through energy scan [CBM Collab., EPJA 53 3 (2017) 60] • CBM’s unique feature – high statistics measurement of rare probes • HADES marks lowest point of the excitation functions Running Approved Conceptual design

  26. FAIR is a multi-purpose(strong interaction) facility • SIS18 tunnel upgrade – finished • Excavation of SIS100 tunnel progresses rapidly • Serial production of major components for SIS100 started • CBM cave readiness 2022 • SIS100 commissioningwith beam 2025 Cryobypas line SIS100 Dipole Cryo catcher Dipole, quadrupole units Bunch compressor RF Cavity System

  27. The CBM strategy RICH Dipole TRD TOF • Fixed target experiments • obtain highest luminosities • Versatile detector systems • optimal setup for given observable • Tracking based entirely on silicon • fast and precise track reconstruction • Free-streaming FEE • nearly dead-time free data taking • On-line event selection • high-selective data reduction HADES MUCH (parking pos.) PSD STS MVD ECAL Day-1setup: Rint= 0.5 MHz (0.1 MHz with MVD) Phase-1 setup: Day-1+ECAL+Compute Performance  Rint= 10 MHz

  28. Thermal dileptons excitation functions • Mll<1 GeV/c2 • r dominates, ‘melts’ close to Tc • Yield in low-mass window tracks fireball lifetime • Search for ”extra radiation” around phase transition(& critical point?) [NA60: Chiral 2010, AIP Conf.Proc. (2010) 1322 STAR: PLB 750 (2015), arXiv:1810.10159] • Mll>1 GeV/c2 • Measures true T (no blue shift) of emitting source from fit of acceptance corrected thermal spectra with M3/2exp(-M/Ts) • Plateau around onset of deconfinement? • [R. Rapp, H. van Hees, PLB 753 (2016) 586 • T. Galatyuk et al.: EPJA 52 (2016) 131]

  29. HADES – CBM complementarity CBM Au+Au 4A GeV

  30. Thankyou for youattention

  31. Extra slides

  32. Pion-proton resonances in medium • Novelmethod of iterativebackgroundestimation [arXiv:1808.05466] • First precise data on in-medium ppresonances D++ D0 Sensitive to the Coulomb force? → useful to extractspace-timeevolution of the fireball

  33. AngulardistributionsTotal e+e-yield 0.28 < Mee (GeV/c2) 0.14 < Mee (GeV/c2) < 0.28 • "Helicity" angle, between e+/- in g* frame and g* in the frame of itssource • Meaning of the observable [PLB 348 283 (1995)]: • Dalitzdecays of pseudoscalarmesons: A = +1 • D→Ne+e-: A = +1 • Bremsstrahlung in softphotonapproximation: A small • r from ppannihilation: A = -1 (with respect to the direction of one of p) • In HIC thermalizationmaywash out the anisotropy (?) Exclusive np→npe+e- GeV HADES, EPJA 53, 149 (2017) 0.15 < Mee (GeV/c2) < 0.3 0.3 < Mee (GeV/c2) < 0.45 0.45 < Mee (GeV/c2) < 0.6 0.6 < Mee (GeV/c2) < 1.0

  34. Tetyana Galatyuk | FAIR : CBM | Town Meeting, CERN | 24 Oct 2018 Core Physics Motivation • The QCD Equation-of-State • Collective behavior (flow anisotropies) • Multi-strange baryons • Hyperon-N, Hyperon-Hyperon interactions • Search for exotic phases and 1st order phase transition • E-b-e observables (higher moments) • Dilepton production (“caloric curve”) • Is there a Critical point? • Net-baryon number fluctuations • Dilepton production (low-mass dilepton excess yield) • Path to restoration of chiral symmetry • High-precision dilepton invariant massdistributions at low- and intermediate masses • Strange matter • (Double-) lambda hypernuclei • Meta-stable objects (e.g. strange di-baryons) • Charm production (and propagation) at threshold • pp, pA [CBM Collab., EPJA 53 (2017) 60] Strong interest internationally • RHIC BES, NA61 SPS, MPD NICA (BM@N) • NA60+ SPS, CEE HIAF, HI injector J-PARC

  35. Triangularanisotropy v3{YRP} Sensitivity to the equation of state

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