1 / 39

Are di-leptons sensitive messengers from the hot and dense stage

Marcus Bleicher, Di-lepton Workshop, Trento 2007. Thanks to the UrQMD group. Katharina Schmidt Sascha Vogel Xianglei Zhu Daniel Krieg Horst Stoecker. . Hannah Petersen Ayut Limphirat Stephane Haussler Timo Spielmann Qingfeng Li. Special thanks to C. Sturm (HADES). Marcus Bleicher, Di-lepto

cade
Download Presentation

Are di-leptons sensitive messengers from the hot and dense stage

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. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Are di-leptons sensitive messengers from the hot and dense stage? Marcus Bleicher Institut für Theoretische Physik Goethe Universität Frankfurt Germany

    2. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Thanks to the UrQMD group

    3. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Outline Introduction Baryon densities: methods, results Densities at rho decay Model features Di-leptons Summary

    4. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Tools: Transport approaches

    5. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Motivation

    6. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Do we understand the interesting stages of the reaction?

    7. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Phase trajectories

    8. Marcus Bleicher, Di-lepton Workshop, Trento 2007 What do we want to see? ?in-medium spectral functions Mass shift of the r meson roughly from 770 MeV ? 600 MeV Modified width of the r meson roughly from 150 MeV ? 300 MeV Possibly modifications of f and w ?Do we know the densities to the required precission?

    9. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Problems How are energy density and baryon density defined? (N/V doesn’t work!) - What frame? Landau? Eckardt? - Lorentz contraction? Nucleus? Nucleon? Is the system thermalized? - Viscous contributions in hydro? What are the degrees of freedom?

    10. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Baryon density Define baryon density at point r in the Eckardt frame (vanishing baryon flow) ?I.e. rB(r)= j0B(r) in the frame with jm=(rB,0) Lorentz contraction for the nucleons along the beam axis is taken into account

    11. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Further problem: thermalization Sound definition of the baryon current/density is possible However, free streaming effects are not excluded (the defined baryon density is not thermal) ?consider only particles that have a velocity around to the thermal velocity (similar to three-fluid approach, Brachmann et al) not practical for transport…

    12. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Local baryon densities (Averaged over the positions of all hadrons) Are we able to observe unambiguous signals from the most compressed region of the system?

    13. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Baryon densities in momentum space at the point of the rho decay

    14. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Gain and loss rates of rho mesons Maximal densities reached at t=10,4,2 fm rho production at HADES energies driven by baryon resonance decays at higher energies: major early stage production, but still sizeable tail from decays in the late stage

    15. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Absorption vs decay How are the dileptons calculated? Shining vs decay Strong absorption in the early stages

    16. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Density distributions Distribution baryon density at the point of rho decay or absorption Significantly higher reach in density if absorbed rhos are included. (However, here the integrated rho life times are shorter)

    17. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Density vs rho mass Absorption has the highest reach in density ?shining method necessary? Moderate mass dependence Final feeding from decays around 1-2 ground state density

    18. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Are the dynamical models good enough? Check space-time evolution ?HBT correlations Check particle production ?Pion production (pp?r !) ?Baryon resonances (r from decays !) ?Final state r from pp correlations

    19. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Excitation functions

    20. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Detailed view at low energies

    21. Marcus Bleicher, Di-lepton Workshop, Trento 2007 HBT-Energy dependence Data shows no dramatic features Expansion and decoupling dynamics ok Fireball life time ok

    22. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Why resonances are interesting? There is a (long living) hadronic rescattering stage at FAIR and SPS energies Lifetime and properties of the hadronic stage are defined and probed by resonance production/absorption/re-feeding/decay Use different resonances to explore this stage: e.g. mesons: baryons: Are resonances dissolved/broadened/shifted in matter?

    23. Marcus Bleicher, Di-lepton Workshop, Trento 2007 The rho has additional potential: Hadronic vs leptonic channel

    24. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Decay time distribution of r mesons

    25. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Expected multiplicities

    26. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Di-leptons: Some technical issues Different di-lepton physics: - VMD, EVMD, form factors, - collisional broadening, shining, - explicit r, effective r, instant di-leptons ? Different result from same input! ? Standard / consensus needed Bremsstrahlung?!

    27. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Hadrons?di-leptons

    28. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Comparison to CERES @ 160 AGeV

    29. Marcus Bleicher, Di-lepton Workshop, Trento 2007 FAIR energy: UrQMD

    30. Marcus Bleicher, Di-lepton Workshop, Trento 2007 HADES energies: UrQMD

    31. Marcus Bleicher, Di-lepton Workshop, Trento 2007 HADES energies: IQMD/RQMD

    32. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Di-lepton summary Model differences due to different di-lepton ‘after burner’! Clear hint of non-equilibrium contributions

    33. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Comparison:(R)QMD/UrQMD Transport models yield same results with SAME di-lepton code

    34. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Summary

    35. Marcus Bleicher, Di-lepton Workshop, Trento 2007 ‘Trivial’ physics effects Even without chiral symmetry restauration and in-medium modifications one expects a modification of the r spectral function

    36. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Di-leptons from the r Broadening and mass shift of the r meson In-medium modifications increase towards lower energies

    37. Marcus Bleicher, Di-lepton Workshop, Trento 2007 r mass distribution in C(2AGeV)+C Double hump feature Strong contribution to low mass r’s from N*1520 Only small contributions from pp channel

    38. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Rapidity dependence of masses Test: With increasing rapidity, baryonic contribution outweighs pp channel r mass decreases towards forward rapidity

    39. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Brown-Rho vs. kinematics

    40. Marcus Bleicher, Di-lepton Workshop, Trento 2007 Summary (II) - Detector

More Related