PhysicsPhysics ColloquiumColloquium QCDQCD MatterMatter underunder ExtremeExtreme ConditionsConditions Neda Sadooghi Department of Physics Sharif University of Technology Tehran-Iran October 2006 HowHow everythingeverything began?began? HowHow everythingeverything willwill end?end? TheThe BigBig BangBang TheoryTheory 19271927:: GeorgesGeorges LemaLemaîîtretre (observation)(observation) Friedmann-Robertson-Walker formula 19291929:: EdwinEdwin HubbleHubble (observation)(observation) Light from other galaxies are red-shifted in direct proportion to their distance from the Earth Consequence:Consequence: ExpandingExpanding UniverseUniverse TheThe BigBig BangBang TheoryTheory ToTo explainexplain HubbleHubble’’ss observationobservation BigBig BangBang Theory:Theory: Georges Lemaître and George Gamow SteadySteady StateState Model:Model: Fred Hoyle TheThe UniverseUniverse isis thethe samesame atat anyany timetime TheThe BigBig BangBang TheoryTheory OtherOther alternatives:alternatives: RichardRichard TolmanTolman’’ss oscillatoryoscillatory UniverseUniverse FritzFritz ZwickyZwicky tiredtired lightlight hypothesishypothesis TheThe BigBig BangBang TheoryTheory 1964:1964: thethe discoverydiscovery ofof cosmiccosmic microwavemicrowave backgroundbackground radiationradiation 19641964--present:present: TheThe BigBig BangBang TheoryTheory isis thethe bestbest theorytheory describingdescribing thethe originorigin andand evolutionevolution ofof thethe cosmoscosmos TheThe BigBig BangBang TheoryTheory TheThe UniverseUniverse evolvedevolved fromfrom aa hothot densedense statestate aboutabout 13.713.7 billionbillion yearsyears agoago InIn thethe latelate 19901990’’ss andand earlyearly 2121st centurycentury – COBE – Hubble Space Telescope – WMAP TimeTime LineLine ofof CosmologyCosmology 10 −43 TimeTime LineLine ofof CosmologyCosmology TheThe VeryVery EarlyEarly UniverseUniverse TheThe PlanckPlanck EpochEpoch TheThe SupersymmetrySupersymmetry isis correctcorrect andand TheThe fourfour fundamentalfundamental forcesforces – Gravity – Electromagnetism – Weak nuclear force – Strong nuclear force havehave thethe samesame strengthstrength TimeTime LineLine ofof CosmologyCosmology TheThe GrandGrand UnificationUnification EpochEpoch TheThe UniverseUniverse expandsexpands andand coolscools fromfrom thethe PlanckPlanck EpochEpoch GravityGravity beginsbegins toto separateseparate fromfrom thethe fundamentalfundamental gaugegauge interactionsinteractions Strong nuclear and Electroweak forces AtAt thethe endend ofof thisthis epochepoch thethe strongstrong nuclenuclearar forceforce separatesseparates fromfrom thethe ElectroweakElectroweak forceforce TimeTime LineLine ofof CosmologyCosmology CosmicCosmic InflationaryInflationary EpochEpoch TheThe universeuniverse isis flattenedflattened andand entersenters aa homogeneoushomogeneous andand isotropicisotropic rapidlyrapidly expandingexpanding phasephase AtAt thethe endend ofof InflationInflation isis thethe ReheatingReheating TheThe inflatoninflaton particlesparticles decaydecay intointo aa hothot,, thermalthermal andand relativisticrelativistic plasmaplasma ofof particlesparticles TheThe energyenergy contentcontent ofof thethe universeuniverse isis entirelyentirely radiationradiation TimeTime LineLine ofof CosmologyCosmology EarlyEarly UniverseUniverse TheThe electroweakelectroweak EpochEpoch –– SupersymmetrySupersymmetry BreakingBreaking (1TeV)(1TeV) –– ElectroweakElectroweak SymmetrySymmetry BreakingBreaking –– AllAll thethe fundamentalfundamental particlesparticles acquireacquire aa massmass viavia HiggsHiggs MechanismMechanism –– NeutrinosNeutrinos decoupledecouple ((cosmiccosmic neutrinoneutrino backgroundbackground)) TimeTime LineLine ofof CosmologyCosmology TheThe HadronHadron andand LeptonLepton EpochEpoch One picosecond to one second after the Big Bang PrePre--mattermatter SoupSoup ((QuarkQuark--GluonGluon PlasmaPlasma)) ElectronsElectrons andand positronspositrons annihilateannihilate eacheach otherother Q/antiQ/anti--QQ pairspairs combinecombine intointo HadronsHadrons HadronsHadrons areare mesonsmesons andand baryonsbaryons Lepton/antiLepton/anti--leptonsleptons pairspairs areare annihilatedannihilated byby photonsphotons FormationFormation ofof atomicatomic nucleinuclei (H(H--ions)ions) TimeTime LineLine ofof CosmologyCosmology NucleosynthesisNucleosynthesis 1 sec – 3 min ProtonsProtons andand neutronsneutrons combinecombine intointo atomicatomic nucleinuclei NuclearNuclear fusionfusion occursoccurs asas HH--ionsions collidecollide toto formform heavierheavier elementselements TimeTime LineLine ofof CosmologyCosmology DecouplingDecoupling andand MatterMatter DominationDomination 3 min to One million years after the Big Bang StableStable atomsatoms formform (H(H--atoms)atoms) PhotonsPhotons areare nono longerlonger ableable toto interactinteract stronglystrongly withwith atomatom (T~1eV)(T~1eV) – Cosmic Microwave Background TheThe PrimordialPrimordial DarkDark AgeAge TheThe onlyonly radiationradiation emittedemitted isis thethe 2121 cmcm spinspin lineline ofof neutralneutral HH--atomatom TimeTime LineLine ofof CosmologyCosmology TheThe StelliferousStelliferous Era;Era; StructureStructure FormationFormation 100 million years after the Big Bang StarsStars (Quasars,(Quasars, earlyearly activeactive galaxies)galaxies) GalaxiesGalaxies Groups,Groups, ClustersClusters andand SuperclustersSuperclusters SolarSolar SystemSystem 8 billion years after the Big Bang TodayToday 13.7 billion years after the Big Bang LifeLife CycleCycle ofof StarsStars Red Supergiant Planetary Nebula White Dwarf -> Black Dwarf – Nuclear fusion progresses through heavier elements Si fuses to Iron-56 – But: Iron fusion absorbs energy – No further energy overflow to counteract the gravity, and the interior of the star collapses instantly SupernovaSupernova ExplosionExplosion Increase of mass causes the white Dwarf to be blasted apart in a type Ia supernova which may be many times more powerful than the type II supernovae marking the death of a massive star BlackBlack HoleHole NeutronNeutron StarStar The Birth of a Neutron Star The Basic Idea The central part of the star fuses its way to iron but it can't go farther because at low pressures Iron 56 has the highest binding energy per nucleon of any element, so fusion or fission of Iron 56 requires an energy input Thus, the iron core just accumulates until it gets to about 1.4 solar mmassesasses (the "Chandrasekhar mass"), at which point the electron degeneracy pressure that had been supporting it against gravity gives up and collapses inward At the very high pressures involved in this collapse, it is energetically favorable to combine protons and electrons to form neutrons plus neutrinos The neutrinos escape after scattering a bit and helping the supernova happen, and the neutrons settle down to become a neutron star, with neutron degeneracy managing to oppose gravity Since the supernova rate is around 1 per 30 years, and because most supernovae probably make neutron stars instead of black holes, in the 10 billion year lifetime of the galaxy there have probably been 100 million neutron stars formed TheThe CrabCrab NebulaNebula DeathDeath ofof aa MassiveMassive StarStar == BirthBirth ofof aa NeutronNeutron StarStar NeutronNeutron StarStar –– HighHigh densitydensity ~~ 1010 grgr/cc/cc Mass: 1.4 Mass of the Sun Radius: 10 km –– LowLow TemperatureTemperature <10<10 keVkeV Cold nuclear matter –– HighHigh SpinSpin raterate upup toto 3800038000 rpmrpm –– StrongStrong MagneticMagnetic fieldfield:: HighHigh DensityDensity or Cram all of humanity into a volume the size of sugar cube ! LowLow TemperatureTemperature 2727 CC ~~ 300300 KK ~~ 2626 meVmeV TemperatureTemperature ofof thethe corecore ofof thethe SunSun At neutron star’s birth: 100 MeV energy per nucleon ~ Cooling by neutrino production through UCRA process At T < 10 MeV: Neutrino emission Further cooling: StrongStrong MagneticMagnetic FieldField ~~ EarthEarth’’ss magnetmagnet FieldField:: TheThe bindingbinding energyenergy ofof HH--atomatom inin aa magnetmagnet fieldfield isis 160160 eVeV insteadinstead ofof 13.613.6 eVeV inin nono fieldfield TheThe protonsprotons atat thethe centercenter ofof neutronneutron starsstars areare believedbelieved toto becomebecome superconductorsuperconductor atat 100100 millionmillion KK High temperature superconductor at 100 K TheoreticalTheoretical BackgroundBackground CosmologyCosmology ParticleParticle PhysicsPhysics CondensedCondensed MatterMatter PhysicsPhysics QuantumQuantum ChromodynamicsChromodynamics (QCD)(QCD) Strong nuclear force is described by QCD In QCD quarks and anti-quarks: Constituent of hadrons (Baryons and Mesons) Gluons mediate the strong nuclear force Hadrons are built via the mechanism of Spontaneous Chiral Symmetry Breaking Asymptotic freedom Confinement Interquark potential energy ~ distance between them No free quarks unless at Confinement-Deconfinement phase transition QCDQCD MatterMatter underunder ExtremeExtreme ConditionsConditions PhasesPhases ofof MatterMatter inin thethe earlyearly universeuniverse – Quark-Gluon Plasma (QGP) phase PhasesPhases ofof mattermatter duringduring coolingcooling – Critical Temperatures Spontaneous Chiral Symmetry Breaking Confinement – Deconfinement phase transition PhasesPhases ofof mattermatter inin NeutronNeutron StarsStars – Mechanism of color superconductivity QCDQCD PhasePhase DiagramDiagram QCDQCD MatterMatter underunder ExtremeExtreme ConditionsConditions TheoreticalTheoretical PredictionsPredictions