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
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 Methods:Methods: LatticeLattice GaugeGauge TheoryTheory (non(non--perturbativeperturbative)) – Critical Temperature ~ 170 MeV Confinement-Deconfinement Phase transition Spontaneous Chiral Symmetry Breaking – No possibility to explore the high density region, due to ‘’sign problem’’ PerturbationPerturbation TheoryTheory – Color superconducting phases at high densities – No possibility to explore the phases at moderate densities ColorColor SuperconductivitySuperconductivity
19771977:: B.B. BarroisBarrois andand S.S. FrautschiFrautschi 19841984:: D.D. BailinBailin andand A.A. LoveLove
19981998:: – M. Alford, K. Rajagopal and F. Wilczek (Nobel Laureate 2004) – R. Rapp, T. Schaefer, E. Shuryak and M. Velkovsky They did calculation in the limit of infinite density QEDQED SuperconductivitySuperconductivity TheThe BasicBasic IdeaIdea
A metal can be viewed as a Fermi liquid of electrons
Below a critical temperature, an attractive phonon mediated interaction between the electrons causes them to pair up
Two electrons form a condensate of Cooper pairs – Consequence: Infinite conductivity
QED Higgs Mechanism makes the photon massive – Consequence: QED Meissner Effect i.e. Exclusion of magnetic fields QCDQCD SuperconductivitySuperconductivity
Quarks are fermions and carry both electric and color charge
Quarks have different colors (red, green and blue) and different flavors (upup,, down and strange)
Different pattern of QCD Cooper pairing is possible
Instead of SSB of QED, here SSB of QCD
Gluons become massive and mediate the strong interaction between the diquark pair
At infinite densities the CFL (color-flavor locked) phase is favored QCDQCD SuperconductivitySuperconductivity ObservableObservable SignaturesSignatures
CoolingCooling ofof thethe CompactCompact StarStar – The compact star starts out freshly created by a supernova 10000 times hotter than the core of our Sun – The star cools not via the radiation from its surface, but mainly by emitting neutrinos from its interior – Color superconducting quark matter cools very slowly in a way that is consistent with observed cooling curves QCDQCD SuperconductivitySuperconductivity ObservableObservable SignaturesSignatures
DynamicsDynamics ofof thethe rotatingrotating compactcompact starstar – Most forms of color superconducting quark matter are superfluids (fluids with no viscosity) where unstable flows (r-modes) is built – r-modes would rapidly carry off the angular momentum, causing its spin to slow down quickly – If the core of compact stars is built of color superconductive quark matter, then r-modes must be built and this permits a rapid spin down QCDQCD SuperconductivitySuperconductivity OpenOpen QuestionsQuestions
TheThe exactexact CriticalCritical DensityDensity
QCDQCD superconductivitysuperconductivity atat moderatemoderate densitiesdensities
NewNew phasesphases ofof QCDQCD QuarkQuark MatterMatter LittleLittle BangBang
ExperimentalExperimental effortsefforts withwith thethe aimaim – Search for QGP around the range of tricritical point – Check the predicted QCD Phase Diagram as far as possible – Determine the critical temperature of various phase transitions experimentally – Find new phases of matter under extreme conditions (see new successes at RHIC) LittleLittle BangBang
SinceSince 20002000 experimentsexperiments atat BrookhBrookhavenaven NationalNational LaboratoryLaboratory (BNL)(BNL) RHIC (Relativistic Heavy Ion Collider) AfterAfter 20082008 atat CERNCERN LHC (Linear Hadron Collider) AuAu –– AuAu CollisionCollision RelativisticRelativistic AuAu--AuAu CollisionCollision
Au-ions collide with 99.7% speed of light
The energy that dump in the microscopic fireball
The pressure generated at the time of impact is atmospheric pressure
Expected: a gas of hot and dense quark matter can be built
QGP – Q(Q) are build via pair production from vacuum – Thermal gluons due to pair annihilation NewNew StateState ofof QCDQCD MatterMatter AA newnew PuzzlePuzzle ?? Theoretical prediction: – At RHIC the hot and dense quark matter should behave as an ideal, weakly interacting gas Instead: It exhibits – A collective (elliptic) flow of almost a perfect liquid at thermal equilibrium – A pressure gradient in QGP (hadron jets have anisotropic spatial distribution) Indication of strongly correlated QGP or sQGP PossiblePossible SolutionSolution
Lattice QCD calculations: – Unable to explain the jet quenching and low viscosity phenomenon String Theory (AdS/CFT correspondence) – Shuryak et al. (2005-2006) Most recent suggestion: – Consider RHIC QGP as Landau chromodynamic material in presence of strong color magnetic field – For strong enough chromomagnetic field only the LLL is occupied – Consequence: The viscosity vanishes