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Electromagnetic Radiation form High Energy Heavy Ion Collisions

Electromagnetic Radiation form High Energy Heavy Ion Collisions. Lecture: Study high T and r QCD in the Laboratory Lecture: Quark matter formation at RHIC Lecture: EM radiation and pioneering experiments at SPS Lecture: An new era: precision measurements with NA60

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Electromagnetic Radiation form High Energy Heavy Ion Collisions

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  1. Electromagnetic Radiation form High Energy Heavy Ion Collisions • Lecture: Study high T and r QCD in the Laboratory • Lecture: Quark matter formation at RHIC • Lecture: EM radiation and pioneering experiments at SPS • Lecture: An new era: precision measurements with NA60 • Lecture: PHENIX at RHIC: the challenge of high energies • Lecture: Medium modifications of open charm production • Lecture: Modified meson properties: insights with low energies • Lecture: The quest to detect for thermal radiation • Lecture: Outlook into the future (mostly RHIC) Tu We Th Fr

  2. Standard model Fundamental Forces in Nature Gravity General Relativity Electro-weak Quantum Field Theory Strong interaction (QCD) Although we have fundamental theories for all forces we need ~20 parameters, constants of unknown origin to describe nature. • Two outstanding puzzles: • unseen quarks  confinement • broken symmetries  existence of massive particles Both connected to complex structure of vacuum Axel Drees

  3. Vacuum low resolution Axel Drees

  4. Vacuum high resolution Vacuum is see of qq pairs (+ gg pairs + ..) Vacuum expectation value for u or d quarks <qq > ~ - (230 MeV)3 Vacuum density of u and d pairs ~ 3 fm-3 Axel Drees

  5. Confinement • Quarks and gluons carry color the charge of QCD • In nature only color neutral objects exist • Bag model: qqq baryons qq mesons Pressure of vacuum (B) compensated by internal pressure bag constant B1/4 ~ 200 MeV 0.8 fm Axel Drees

  6. r  VQCD r > rbag  r r 1 fm r < rbag 1S 1P 2S cc  1/r 1S 2S 3S 4S bb String Models String with tension s ~ 1 GeV/fm QCD potential: Need infinite energy to separate quarks  confinement (relation to <qq> ??) charmonuim and bottonium states explore QCD potential Axel Drees

  7. s p spin momentum s p right handed left handed Chiral Symmetry • Chirality (handedness) or helicity for massless particles chirality is conserved • QCD with 3 massless quarks (flavors) symmetry qR does not couple to qL • Masses break symmetry if mass  0 qR couples to qL right-handed left-handed Axel Drees

  8. Masses of Quarks • spontaneous breaking of electro-weak interaction  current mass of quark for u & d quarks mou ~ mod ~ 5 MeV s quark mos ~ 175 MeV explicitly breaking of chiral symmetry • spontaneous breaking of chiral symmetry  constituent mass of quarks for u & d quarks mu ~ md ~ 300 MeV (~1/3 mproton ) s quark mos ~ 500 MeV spontaneous breaking of chiral symmetry q q couples toqq see qq q coupling G Axel Drees

  9. V V external force ground state Symmetry Breaking • Spontaneously • Explicit massless Goldstone bosons here p+p-po (2 flavors) potential symmetric symmetry broken for ground state potential symmetric ground state symmetric V massive p+p-po Mass small ~ 140 MeV potential asymmetric Axel Drees

  10. 1+ a1 (1270 MeV) 1 1-r (770 MeV) Consequences of Spontaneous Symmetry Breaking • 1) all hadrons have well defined parity • chiral symmetry qRqR = qLqL expect Jp doublets • characteristic mass scale of hadrons • 1 GeV mass gap to quark condensate • except pseudoscaler mesons • Goldstone bosons: p, h, and K Axel Drees

  11. Origin of Mass • current quark mass • generated by spontaneous symmetry breaking (Higgs mass) • contributes ~5% to the visible (our) mass • constituent quark mass • ~95% generated by spontaneous chiral symmetry breaking (QCD mass) Axel Drees

  12. Fundamental Puzzles of Hadrons nuclear matter p, n • Confinement • Quarks do not exist as free particles • Large hadron masses • Free quark mass ~ 5-7 MeV • Quarks become “fat” in hadrons constituent mass ~ 330 MeV • Complex structure of hadrons • Sea quarks and anti quarks • Gluons • “spin crisis” Spin of protons not carried by quarks! These phenomena must have occurred with formation of hadrons Axel Drees

  13. ~ 10 ms after Big Bang Hadron Synthesis strong force binds quarks and gluons in massive objects: protons, neutrons mass ~ 1 GeV/c2 ~ 100 s after Big Bang Nucleon Synthesis strong force binds protons and neutrons bind in nuclei Axel Drees

  14. ~ 10 ms after Big Bang T ~ 200 MeV Hadron Synthesis strong force binds quarks and gluons in massive objects: protons, neutrons mass ~ 1 GeV/c2 Planck scale T ~ 1019 GeV End of Grand Unification inflation ~ 100 ps after Big Bang T ~ 1014 GeV Electroweak Transition explicit breaking of chiral symmetry Axel Drees

  15. early universe T RHIC & LHC Quark Matter SPS TC~170 MeV AGS SIS Hadron Resonance Gas temperature Nuclear Matter neutron stars baryon chemical potential 1200-1700 MeV 940 MeV mB “Travel” Back in Time • QGP in Astrophysics • early universe after ~ 10 ms • possibly in neutron stars • Quest of heavy ion collisions • create QGP as transient state in heavy ion collisions • verify existence of QGP • Study properties of QGP • study QCD confinement and how hadrons get their masses Axel Drees

  16. Quark-Gluon Plasma q, g nuclear matter p, n density or temperature Estimating the Critical Energy Density distance of two nucleons: 2 r0 ~ 2.3 fm size of nucleon rn ~ 0.8 fm • normal nuclear matter r0 • critical density: • naïve estimation • nucleons overlap R ~ rn Axel Drees

  17. Critical Temperature and Degrees of Freedom Noninteracting system of 8 gluons with 2 polarizations and 2 flavor’s of quarks (m=0, s=1/2) with 3 colors • In thermal equilibrium relation of pressure P and temperature T • Assume deconfinement at mechanical equilibrium • Internal pressure equal to vacuum pressure B = (200 MeV)4 • Energy density in QGP at critical temperature Tc Axel Drees

  18. QCD calculations • perturbative QCD calculations applicable only for large momentum transfer  small coupling • for small momentum transfer  large coupling only solution numerical QCD calculations on lattice results from lattice QCD establish the QCD phase transition Critical energy eC = 62 TC4 jump in energy density: TC ~ 155-175 MeV eC ~ 0.3-1.0 GeV/fm3 critical temperature TC Axel Drees

  19. The QCD phase transition Change of order parameter: deconfinement: Polyakov loop L ~ e-Fq chiral symmetry: Quark condensate qq different quark mass mq Polyakov loop response function deconfinement chiral restoration and deconfinement at same critical temperature TC ~ 170 MeV chiral susceptibility chiral symmetry restoration 165 MeV 175 MeV temperature Axel Drees

  20. QCD Potential from Lattice Calculations As temperature increases towards TC the QCD potential vanishes at large distances Axel Drees

  21. Restoration of Chiral Symmetry In hot and dense matter chiral symmetry is restored model calculation (Nambu, Jona-Lasinio) • Temperature axis: • sharp transition at TC (similar to lattice QCD results) • baryon density axis: • smooth transition • at nuclear matter density approaching of chiral symmetry restoration should strongly modify hadron properties like  and m Axel Drees

  22. String Theory (AdS/CFT Correspondence) A new approach to calculate properties of the QGP • Standard model describes all phenomena in nature, but is a disjoint framework • Forces: • Gravity  general relativity (classical) • Electromagnetic, Weak, and Strong  gauge theory (quantum) • Matter: • 6 quarks, 6 leptons, plus Higgs • In string theory strings are basis of all forces • Open strings: gauge theory • Closed strings: gravity 10-34 m (Next slides based on talk by Makoto Natsuume at RHIC/AGS Users Meeting 2008) Axel Drees

  23. Duality of Theories that Look Different • Tool in string theory for 10 years • Strong coupling in one theory corresponds to weak coupling in other theory • AdS/CFT duality (Anti deSitter Space/ Conformal field theory) (in QCD) (N=4 SYM) Axel Drees

  24. Relevance for Heavy Ion Collisions • New matter formed at RHIC resembles fluid • QGP near phase boundary seems a strongly coupled plasma • Lower bound on Viscosity/Entropy from AdF/CFT duality Axel Drees

  25. Study high T and r QCD in the Laboratory Quark Matter: Many new phases of matter Asymptotically free quarks & gluons Strongly coupled plasma Superconductors, CFL …. Experimental access to “high” T and moderate r region: heavy ion collisions Pioneered at SPS and AGS Ongoing program at RHIC Exploring the Phase Diagram of QCD T Quark Matter Mostly uncharted territory sQGP TC~170 MeV Hadron Resonance Gas Overwhelming evidence: Strongly coupled quark matter produced at RHIC temperature Nuclear Matter baryon chemical potential 1200-1700 MeV 940 MeV mB Axel Drees

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