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Universal Signal of Quark Gluon Plasma -

Universal Signal of Quark Gluon Plasma -. /e + e -. BIKASH SINHA. SAHA INSTITUTE OF NUCLEAR PHYSICS AND VARIABLE ENERGY CYCLOTRON CENTRE KOLKATA, INDIA. arXiv:0705.1591 [nucl.th]. B.S. PLB 1983.

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Universal Signal of Quark Gluon Plasma -

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  1. Universal Signal of Quark Gluon Plasma - /e+e- BIKASH SINHA SAHA INSTITUTE OF NUCLEAR PHYSICS AND VARIABLE ENERGY CYCLOTRON CENTRE KOLKATA, INDIA arXiv:0705.1591 [nucl.th]

  2. B.S. PLB 1983 Sometime ago it was noted that:“The ratio of the production rates (/+-) and ( o,/+-) from quark gluon plasma is independent of the space time evolution of the fireball”.Universal Signal : (1) (2) (3) Only a function of universal constants.

  3. Light from QGP qq m+m-~ T4 B.S. PLB 1983 m+ q q m- R  / m+m- = const( a, as)

  4. Thermal Photons Invariant yield of thermal photons can be written as i  Q  QGP M  Mixed (coexisting phase of QGP and hadrons) H  Hadronic Phase is the static rate of photon production  convoluted over the space time expansion.

  5. Thermal photons from QGP : using hard thermal loop approximation. Again, Resumming ladder diagrams in the effective theory Thermal photons from hadrons : (i)  (ii)  (with , , ,  and a1, in the intermediate state) (iii)  (iv) ,  and  & Similarly from strange meson sector

  6. Dileptons • Rather similar to photons, dileptons can be efficient probe for QGP – again not suffering from final state interactions. • One has to subtract out contributions from: • (a) Drell–Yan process, • (b) Decays of vector mesons within the life time of the fireball • (c) Hadronic decays occurring after the freeze out. • Invariant transverse momentum distribution of thermal dileptons (e+e- or virtual photons, *): integrated over the invariant mass region:

  7. Consistent with e+e- V(r,w,f) data Dileptons from light vector mesons (, ) &  (Hadronic Sector) : fV(V) :coupling between electromagnetic current and vector meson fields mV and GV are the mass and width of the vector V and w0 are the continuum threshold above which the asymptotic freedom is restored.

  8. Isentropic expansion : Hydrodynamics takes care of the evolution of the transverse motion.

  9. The number density as a function of temperature. Effect of mass modification and width modification is shown.

  10. Photons at SPS

  11. Thermal Photon reproduce WA98 data

  12. Di-electrons at SPS

  13. Photons at RHIC (J. Phys. G 2007, J. Alam, J. Nayak, P.Roy, A. Dutt-Mazumder, B.S.)

  14. Thermal Photon reproduce PHENIX data

  15. Di-electrons at RHIC

  16. Photons at LHC

  17. Di-electrons at LHC

  18. RESULTS from the ratio: The variation of Rem (the ratio of the transverse momentum spectra of photons and dileptons) has been studied for SPS, RHIC and LHC. We argue that simultaneous measurements of this quantity will be very useful to determine the value of the initial temperature of the system formed after heavy ion collisions. We observe that Rem reaches a plateau beyond PT=0.5 GeV. The value of Rem in the plateau region depends on Ti but largely independent of Tc, vo, Tf and the EOS.

  19. Ratio (Rem) at SPS

  20. Ratio (Rem) at RHIC

  21. Ratio (Rem) at LHC

  22. Ratio (Rem) for pQCD processes FILTERING OUT pQCD PHOTONS

  23. Ratio (Rem) vs. Initial Temperature arXiv:0705.1591 [nucl.th]

  24. OBSERVATIONS: • The medium effect on Rem is negligibly small • Hydrodynamic effects such as viscosity, flow get sort of erased out by observing the ratio, Rem • Equivalently, model dependent uncertainties also get cancelled out through Rem • Contributions from Quark Matter increase with the increase of the initial temperature – • thermal photons mostly for hadronic phase at SPS • thermal photons from RHIC and more so from LHC originate from QGP • Rem flattens out beyond pT ~ 0.5GeV • In the plateau region: RemLHC > RemRHIC>RemLHC

  25. OBSERVATIONS, contd. WHY & HOW Rem (in Born approx.) => At the end Rem still remains by far and large model independent: SPS => RHIC => LHC Thus Rem is a universal signal of QGP, model independent and unique.

  26. In an expanding system, however, Rem involves the superposition of results for all temperatures from Tito Tf, so the effective (average) temperature, Teff will lie between Ti and Tf and We see that is a function of the universal constants and the temperature. Because of the slow (logarithmic) variation as with temperature, one can assume This explains: It is also interesting to note that for as = 0.3, T=0.4GeV, (DM)2 ~ 1 (Mmax=1.05, Mmin=0.28), we get: Rs~ 260. This is comparable to Rem obtained in the present calculation.

  27. WHAT DO WE EXPECT at LHC

  28. Photons and di-electrons in the ALICE experiment TRD: Electron-pairs PHOS: Photons

  29. Muon chambers PMD Modules MUON arm m-pairs PMD photons

  30. LOOKING FORWARD TO THE VERIFICATION OF THE UNIVERSAL SIGNATURE: /e+e- as well asg/m+m- at the Large Hadron Collider

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