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Unturned Stones for Electromagnetic Probes of Hot and Dense Matter

Unturned Stones for Electromagnetic Probes of Hot and Dense Matter. Hot Quarks 2006, May 15-20, 2006, Villasimius, Sardinia, Italy. Kevin L. Haglin. St. Cloud State University, Minnesota, USA. What’s under those stones? Photons a) thermometry b) flow 2) Dileptons

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Unturned Stones for Electromagnetic Probes of Hot and Dense Matter

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  1. Unturned Stones for Electromagnetic Probes of Hot and Dense Matter Hot Quarks 2006, May 15-20, 2006, Villasimius, Sardinia, Italy Kevin L. Haglin St. Cloud State University, Minnesota, USA Hot Quarks 2006

  2. What’s under those stones? • Photons • a) thermometry • b) flow • 2) Dileptons • c) vector meson spectroscopy • d) collective many-body effects • 3) Diphotons • e) thermal production - thermometry • f) scalar and tensor meson spectral functions • g) hadron spectroscopy • 4) J/y & hc g, g* [e+e-, m+m-], gg J/y, hc Hot Quarks 2006

  3. 3) Diphotons • It turns out that studies of photon pair production have a fairly long history…. • R. Yoshida, T. Miyazaki, M. Kadoya, PRD 35, 388 (1987). • K. Redlich, PRD 36, 3378 (1987). • J. Letessier and A. Tounsi, PRD 40, 2914 (1989). • R. Baier, H. Nakkagawa, A. Niegawa, K. Redlich, PRD 45, 4323 (1992). • M. Hentschel, B. Kampfer, O.P. Pavlenko, K. Redlich, G. Soff, Z. Fur • Phys. C, 333 (1997). + crossed diagram + crossed + contact Hot Quarks 2006

  4. Motivation: That is, suggestions at the time (1990) were…. • at fixed temperature • ratio of dNgg/dydM to (dNch /dydM)2 should exhibit a more abrupt change in slope when the phase boundary is crossed as compared to ordinary hadronic matter • Difficulties: • Fold the rates to predict yields, and the “effect” diminishes owing to the long lifetime of the hadron phase • b) Drell-Yan “like” photon pairs dominates at some point Hot Quarks 2006

  5. New idea… let’s use the diphoton signal to do • Thermometry • rate is proportional to exp(- Mgg/T) times a function of T • 2) Spectroscopy • tensor mesons couple to 2g [f2(1270), a2(1320), f2’(1525), …] • f1(1285)  gg [G(f1gr0) = 1.3 MeV] • scalar, pseudoscalar mesons couple to 2g [s, h’ , f0, a0, h(1475)] • 3) Heavy quark physics • hc2g with rate 7.4 keV (full width is 17.3 MeV) • cc02g with rate 2.6 keV (full width is 10.1 MeV) do spectroscopy! What are the major background contributions? Hot Quarks 2006

  6. Inventory Hadron processes QCD processes Singles masquerading as doubles Meson spectral functions charmonium Hot Quarks 2006

  7. Hadron annihilation processes M. Hentschel, B. Kampfer, O.P. Pavlenko, K. Redlich, G. Soff, Z. Fur Phys. C, 333 (1997). Hot Quarks 2006

  8. QCD annihilation processes [screened, net (resummed) rate] where c is approximately 0.42. The range of validity is M > T. R. Baier, H. Nakkagawa, A. Niegawa, K. Redlich, PRD 45, 4323 (1992). q g q Hot Quarks 2006

  9. Hadron phenomenology g p ,K g ,K p g p ,K p g ,K p g ,K p ,K g Vertex form factors: Hot Quarks 2006

  10. More phenomenology… g r ,K* g ,K* r g r ,K* r g ,K* r g ,K* r ,K* g Chiral Lagrangian from KH, C. Gale, PRC 63, 065201 (2001). Hot Quarks 2006

  11. Comments: • Quark rate comes from re-summed (HTL) thermal field theory • Pion and kaon results are diagrammatic calculations w/o form factors • V +V -  gg use chiral Lagrangian to identify the interactions • ww  gg use Wess-Zumino interaction The QCD rate seems to be quite similar to the HG rate! KLH, to be published. Hot Quarks 2006

  12. Hadron thermal decay into photon pairs g g p s a p = p g g + others Hot Quarks 2006

  13. Results: • Diphoton rate from QGP vs. HG seems roughly the same at fixed temperature. • This is the same conclusion one had with single photons. • A temperature can be extracted – thermometry • Meson spectral properties at finite temperature can be probed – spectroscopy, in-medium physics • Chiral restoration  f1 spectral function should approach equivalence with w. KLH, to be published. Hot Quarks 2006

  14. Singles “looking like doubles” Parameterization from J. Kapusta, P. Lichard, D. Seibert, PRD 44, 2774 (1991). And we take where Hot Quarks 2006

  15. Two comments: • HG and QGP can now be compared directly on this figure---they are very similar. • The singles’ corruption of the double is negligible. Hot Quarks 2006

  16. Next, let’s establish the relative importance of form factors. • Of course, at high mass off-shell behavior will become more important. • Results of monopole form factors: • Low mass pairs are reduced by a factor of 2 • High mass pairs suffer an order of magnitude suppression. Hot Quarks 2006

  17. 4) Charmonium: “suppression of hc as QGP indicator”! The same idea for J/y suppression carries over to hc. Full width for hc is 17.3 MeV. It should stand “tall and proud” unless it is disturbed by the QGP!! The other charmonium states represent additional tools---it’s all good. Hot Quarks 2006

  18. Summary • Bursts of electromagnetic energy cleanly probe the full space-time extent of the strongly-interacting system. 2) Photons allow thermometry 3) Dileptons provide spectroscopic information on vector mesons at finite energy density 4) Diphotons open the door for both thermometry and spectroscopy 5) Charmonium (eta-charm) suppression could be a very useful QGP diagnostic (if experimental resolution is sufficient). Further studies underway… • More complete hadron description, i.e. form factors • b) space-time evolution for yields; add DY-like pairs Hot Quarks 2006

  19. That’s all folks… Research supported in part by the National Science Foundation under grant number PHY-0555521. Hot Quarks 2006

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