1. HADES The Baryon-rich Side of the Phase Diagram
Au+Au collisions at √sNN = 2.4 GeV
Strangeness Production
Flow and its Anisotropies
Virtual Photon Emission
Net-Proton Fluctuations
Manuel Lorenz for the HADES Collaboration
QM 2017 Chicago

2. The Baryon-rich Side of the Phase Diagram
K. Fukushima
HADES: Au+Au √sNN=2.4 GeV
Large stopping and interpenetration times
 Baryon dominated system
system

3. The Baryon-rich Side of the Phase Diagram
Virtual Photon Emission:
Vector meson spectral functions modified
by coupling to baryons
Strangeness Production:
Strong kinematical suppression of direct K-
NNNYK+ √sNN= 2.55 GeV
NNNNK+K- √sNN= 2.86 GeV
Strong coupling of K- to baryons
strangeness exchange reactions e.g. πYNK-
Flow Anisotropies:
Preferred out-of-plane emission due
to shadowing
Net-Proton Fluctuations:
No Antiprotons, additional terms when
correcting for volume fluctuations
K. Fukushima
HADES: Au+Au √sNN=2.4 GeV
Large stopping and interpenetration times
 Baryon dominated system
system

4. The Baryon-rich Side of the Phase Diagram
Virtual Photon Emission:
Vector meson spectral functions modified
by coupling to baryons
Strangeness Production:
Strong kinematical suppression of direct K-
NNNYK+ √sNN= 2.55 GeV
NNNNK+K- √sNN= 2.86 GeV
Strong coupling of K- to baryons
strangeness exchange reactions e.g. πYNK-
Flow Anisotropies:
Preferred out-of-plane emission due
to shadowing
Net-Proton Fluctuations:
No Antiprotons, additional terms when
correcting for volume fluctuations
K. Fukushima
HADES: Au+Au √sNN=2.4 GeV
Large stopping and interpenetration times
 Baryon dominated system
system
Clear hierarchy in hadron yields:
p ≈ 100, π ≈ 10, K+ ≈ 10-2, K- ≈10-4

5. The Baryon-rich Side of the Phase Diagram
K. Fukushima
©Hosan
HADES: Au+Au √sNN=2.4 GeV
Large stopping and interpenetration times
 Baryon dominated system
system
Fast detector: up to 50 kHz trigger rate
Large acceptance: Full azimuthal and
polar angle coverage of Θ = 18° – 85°
2.1x109 events analyzed
Clear hierarchy in hadron yields:
p ≈ 100, π ≈ 10, K+ ≈ 10-2, K- ≈10-4

6. The Baryon-rich Side of the Phase Diagram
Progress detector driven
K. Fukushima
©Hosan
HADES: Au+Au √sNN=2.4 GeV
Large stopping and interpenetration times
 Baryon dominated system
system
Fast detector: up to 50 kHz trigger rate
Large acceptance: Full azimuthal and
polar angle coverage of Θ = 18° – 85°
2.1x109 events analyzed
Clear hierarchy in hadron yields:
p ≈ 100, π ≈ 10, K+ ≈ 10-2, K- ≈10-4

7. The Baryon-rich Side of the Phase Diagram
Progress detector driven
K. Fukushima
protons
HADES: Au+Au √sNN=2.4 GeV
Large stopping and interpenetration times
 Baryon dominated system
system
Fast detector: 8-50 kHz trigger rate
Large Acceptance: Full azimuthal and
polar angle coverage of Θ = 18° – 85°
2.1x109 events analyzed
Clear hierarchy in hadron yields:
p ≈ 100, π ≈ 10, K+ ≈ 10-2, K- ≈10-4

8. The Baryon-rich Side of the Phase Diagram
Progress detector driven
pions
K. Fukushima
HADES: Au+Au √sNN=2.4 GeV
Large stopping and interpenetration times
 Baryon dominated system
system
Clear hierarchy in hadron yields:
p ≈ 100, π ≈ 10, K+ ≈ 10-2, K- ≈10-4

9. The Baryon-rich Side of the Phase Diagram
Progress detector driven
K. Fukushima Λ
HADES: Au+Au √sNN=2.4 GeV
Large stopping and interpenetration times
 Baryon dominated system
system
First measurement
below NN-threshold
Clear hierarchy in hadron yields:
p ≈ 100, π ≈ 10, K+ ≈ 10-2, K- ≈10-4

10. Macroscopic Description of Hadron Production
Particle production from a
homogeneous source.
Strangeness canonical ensemble
Parameter: T, µB, Rc, R.
Additional parameter to suppress strangeness needed (RC < Rv).
Fits at low beam energies based on limited number of particle species.
Comparison of absolute yield for
different particle species
And ratio data/model in the lower part

11. Macroscopic Description of Hadron Production
THERMUS V2.3:
S. Wheaton, J.Cleymans Comput.Phys.Commun.180:84-106,2009
Particle production from a
homogeneous source.
Strangeness canonical ensemble
Parameter: T, µB, Rc, R.
Additional parameter to suppress strangeness needed (RC < Rv).
Fits at low beam energies based on limited number of particle species.
Au+Au
0-20% most central
Comparison of absolute yield for
different particle species
And ratio data/model in the lower part

12. Macroscopic Description of Hadron Production
THERMUS V2.3:
S. Wheaton, J.Cleymans Comput.Phys.Commun.180:84-106,2009
Particle production from a
homogeneous source.
Strangeness canonical ensemble
Parameter: T, µB, Rc, R.
Additional parameter to suppress strangeness needed (RC < Rv).
Fits at low beam energies based on limited number of particle species.
Au+Au
0-20% most central
Comparison of absolute yield for
different particle species
And ratio data/model in the lower part
Hadron yields described by 4 parameters (T, µB, R, Rc)
Matter formed?

13. (Sub-threshold) Strangeness Production

14. (Sub-threshold) Strangeness Production
Kaons and antikaons show different slopes

15. (Sub-threshold) Strangeness Production
KaoS: Phys.Rev. C75 (2007)
“Later freeze-out of K- compared to K+, due to coupling to baryons and strangeness exchange reactions ??”
Kaons and antikaons show different slopes

16. (Sub-threshold) Strangeness Production
Φ/K- ratio constant at high energies
Prog.Part.Nucl.Phys. 66 (2011)
Important phi over K-!

17. (Sub-threshold) Strangeness Production
Increased in Au+Au collisions at low energies
 25% of K- result from Φ decays!
Prog.Part.Nucl.Phys. 66 (2011)

18. (Sub-threshold) Strangeness Production
Increased in Au+Au collisions at low energies
 25% of K- result from Φ decays!
Φ feed-down can explain lower inverse slope parameter of K- spectrum (Teff = 84 ± 6 MeV) in comparison to the one of K+ (Teff = 104 ± 1 MeV)
Prog.Part.Nucl.Phys. 66 (2011)

19. (Sub-threshold) Strangeness Production
Increased in Au+Au collisions at low energies
 25% of K- result from Φ decays!
Φ feed-down can explain lower inverse slope parameter of K- spectrum (Teff = 84 ± 6 MeV) in comparison to the one of K+ (Teff = 104 ± 1 MeV)
No indication for sequential K+K- freeze-out
if K- spectrum is corrected for feed-down.
Prog.Part.Nucl.Phys. 66 (2011)

20. (Sub-Threshold) Strangeness Production: the Complete Picture
- Strange particle yields rise stronger than linear with <Apart> (M ~ <Apart>α)
- Universal <Apart> dependence of strangeness production
 Hierarchy in production threshold not reflected
NNYK+ √sNN= 2.55 GeV
NNNNK+K- √sNN= 2.86 GeV
 Supports assumption that the production yields reflect matter properties

21. (Sub-Threshold) Strangeness Production: the Complete Picture
- Strange particle yields rise stronger than linear with <Apart> (M ~ <Apart>α)
- Universal <Apart> dependence of strangeness production
 Hierarchy in production threshold not reflected
NNYK+ √sNN= 2.55 GeV
NNNNK+K- √sNN= 2.86 GeV
 Supports assumption that the production yields reflect matter properties
More:
Parallel Session 7.1
Heidi Schuldes
Wednesday
8 Feb 2017, 14:00

22. Flow and its Anisotropies
Progress detector driven
K. Fukushima

23. Flow and its Anisotropies
Progress detector driven
arXiv:
K. Fukushima
Extraction of kinetic freeze-out parameters by blast wave fit to hadron spectra.
Tkin=62±10 MeV, <βr>=0.36±0.04
Λ and ϕ fall out of the trend.
Parameter follow the trend of the world data.

24. Flow and its Anisotropies
Progress detector driven
arXiv:
K. Fukushima
Extraction of kinetic freeze-out parameters by blast wave fit to hadron spectra.
Tkin=62±10 MeV, <βr>=0.36±0.04
Λ and ϕ fall out of the trend.
Parameter follow the trend of the world data.
The full story including v1,v2 of charged hadrons:
Parallel Session 7.1, B. Kardan (talk given by C. Blume)
Wednesday 8 Feb 2017, 14:40

25. Virtual Photon Emission
Progress detector driven
K. Fukushima

26. Virtual Photon Emission
First measurement of e+e- for a
heavy system in this energy regime.
Normalized to the number of π0.
Strong excess yield (0.15<M<0.7 GeV/c2) above e+e- cocktail components of meson
decays at freeze-out and elementary baryonic reference observed.
 Medium radiation
Progress detector driven
K. Fukushima

27. Virtual Photon Emission
First measurement of e+e- for a
heavy system in this energy regime.
Normalized to the number of π0.
Strong excess yield (0.15<M<0.7 GeV/c2) above e+e- cocktail components of meson
decays at freeze-out and elementary baryonic reference observed.
 Medium radiation
Isolation of the excess by subtracting the elementary reference and the η-contribution.
Acceptance corrected excess yield.
Progress detector driven
K. Fukushima

28. Virtual Photon Emission
First measurement of e+e- for a
heavy system in this energy regime.
Normalized to the number of π0.
Strong excess yield (0.15<M<0.7 GeV/c2) above e+e- cocktail components of meson
decays at freeze-out and elementary baryonic reference observed.
 Medium radiation
Isolation of the excess by subtracting the elementary reference and the η-contribution.
Acceptance corrected excess yield.
Exponentially falling spectrum,
 extraction of source temperature
Progress detector driven
K. Fukushima

29. Centrality Dependence of Virtual Photon Emission
Dileptons: 0.3<M<0.7 GeV/c2
K. Fukushima
α = 1.37 ± 0.18

30. Centrality Dependence of Virtual Photon Emission
Dileptons: 0.3<M<0.7 GeV/c Strange Particles
K. Fukushima
α = 1.37 ± 0.18
Similar <Apart> dependence!

31. Centrality Dependence of Virtual Photon Emission
Dileptons: 0.3<M<0.7 GeV/c Strange Particles
K. Fukushima
α = 1.37 ± 0.18
Similar <Apart> dependence!
More:
Parallel Session 1.3, Tetyana Galatyuk,Tuesday 7 Feb 2017, 8:50

32. (Net)-Proton Number Fluctuations
Progress detector driven
K. Fukushima

33. (Net)-Proton Number Fluctuations
Things to consider:
Phase space region, not too big not too small (No spectators, and check against Poisson limit).
Extracted moments must be corrected for detector response. Two methods tested and validated with simulations.
Volume number fluctuations for a given centrality selection, no antiprotons, no terms cancel!
Various effects and their impact on the corrected moments systematically studied.
Progress detector driven
K. Fukushima

34. (Net)-Proton Number Fluctuations
Progress detector driven
K. Fukushima

35. (Net)-Proton Number Fluctuations
Progress detector driven
K. Fukushima
Get the full story:
Parallel Session 8.1, Romain Holzmann, Wednesday 8 Feb 2017, 17:10

36. Summary Tchem=68±2 MeV extracted from statistical model fit.
No indication for sequential K+K- freeze-out when correcting for ϕ feed-down, common rise of strange hadron multiplicities with <Apart>.
Parallel Session 7.1, H. Schuldes 8 Feb 2017, 14:00
Tkin=62±10 MeV and <βr>=0.36±0.04 extracted from blast wave fit.
Parallel Session 7.1, B. Kardan (talk given by C. Blume) 8 Feb 2017, 14:40
Strong e+e- excess over reference, exponentially falling spectrum, extracted source temperature Tee=71±4 MeV, similar rise with <Apart> as observed for strange hadrons.
Parallel Session 1.3, T. Galatyuk 7 Feb 2017, 8:50
First attempt of extracting fluctuations (corrections!) of net-proton distribution from data at low √s, continuing the excitation function measured by STAR.
Parallel Session 8.1, R. Holzmann 8 Feb 2017, 17:10
Investigations on direct photons.
Poster Session, C. Deveaux 6 Feb 2017, 16:00

37. The HADES collaboration
Thank you for your attention!