richard seto ucr csula – 11/17/2010

45
Strings and Things: The Discovery of the strongly interacting Quark Gluon Plasma at the Relativistic Heavy Ion Collider Richard Seto UCR CSULA – 11/17/2010

Upload: amora

Post on 22-Mar-2016

37 views

Category:

Documents


1 download

DESCRIPTION

Strings and Things: The Discovery of the strongly interacting Quark Gluon Plasma at the Relativistic Heavy Ion Collider. Richard Seto UCR CSULA – 11/17/2010. What happens if you cook the nucleus?. Why ask the question? Large scale QCD system we have NO IDEA what it is really like - PowerPoint PPT Presentation

TRANSCRIPT

Page 1: Richard Seto UCR CSULA – 11/17/2010

Strings and Things: The Discovery of the strongly interacting Quark Gluon Plasma at the Relativistic Heavy Ion Collider

Richard SetoUCR

CSULA – 11/17/2010

Page 2: Richard Seto UCR CSULA – 11/17/2010

What happens if you cook the nucleus? Why ask the question?

Large scale QCD system we have NO IDEA what it is really like

Properties (dynamical – lattice can calculate static only)

viscosity thermal conductivity ???

innovations in both experiments and theory Strings hydro models (3d viscous relativistic) initial state – new non-perturbative QCD methods

Page 3: Richard Seto UCR CSULA – 11/17/2010

Fermi asked the question

RHIC

From Fermi notes on Thermodynamics

Page 4: Richard Seto UCR CSULA – 11/17/2010

4

Page 5: Richard Seto UCR CSULA – 11/17/2010

The Phase diagram (water)

Pressure

Tem

pera

ture

Gas

Liquid

Solid

Phase Transition: Tc = 273K

TC

Page 6: Richard Seto UCR CSULA – 11/17/2010

The Phase Diagram (Nuclear Matter)

Phase Transition: Tc = 190 MeV = 1012K e ~ 0.6 GeV/fm3

Tc

6

Tem

pera

ture

Baryon Density

Page 7: Richard Seto UCR CSULA – 11/17/2010

Collide Au + Au ions for maximum volumes = 200 GeV/nucleon pair, p+p and d+A to compare

BNL-RHIC Facility

STAR

In the last few days: LHC

7

Page 8: Richard Seto UCR CSULA – 11/17/2010

What does an Au+Au Collisions at 200 GeV Center of mass look like?

Page 9: Richard Seto UCR CSULA – 11/17/2010

trans

vers

e m

omen

tum

pt

time

Relativistic Heavy Ion Collisions Lorenz contracted pancakes Pre-equilibrium < ~1fm/c ?? QGP and hydrodynamic

expansion ~ few fm/c ??

Stages of the Collision

Tc ~ 190 MeV

T

time

Tinit=?PuresQGP

τ09

Pure water

Mixed phase

Page 10: Richard Seto UCR CSULA – 11/17/2010

10

I.Temperatureunits 1eV~10,000K

Use E=kT

Page 11: Richard Seto UCR CSULA – 11/17/2010

Measuring the Temperature: Black Body radiation (Serway)

11

photons

photons

Photon energy(wavelength) spectrum gives temperature

How do you Measure T?

Page 12: Richard Seto UCR CSULA – 11/17/2010

Make a measure of low pT photons (black body radiation)

Do a fit to models T~300 MeV

depending on Model Greater than TC!

◦ Tc ~190 MeV

IT’S HOT ENOUGH !

Thermal photons - Temperature from the data

12

pQCD

Energy

Inte

nsity Thermal

photons

Page 13: Richard Seto UCR CSULA – 11/17/2010

13

II. Jet quenching and energy density

Page 14: Richard Seto UCR CSULA – 11/17/2010

Remember Rutherford Scattering?(Serway 29.1)

14

Page 15: Richard Seto UCR CSULA – 11/17/2010

Hard Probes In Heavy Ion Collisions, aka Jet quenching

The experiment we would like to do – Rutherford Scattering of the QGP

PCM & clust. hadronization

NFD

NFD & hadronic TM

PCM & hadronic TM

CYM & LGT

string & hadronic TMhadronizationpre-equilibrium

QGP andhydrodynamic expansion

hadronic phaseand freeze-outHard parton

Softened Jet

ColorlessHadrons

ColoredQGP

Beams of colored quarks

“hard” probes Formed in initial collision with high

Q2 penetrate hot and dense matter sensitive to state of hot and dense matter

Energy loss by strong interaction jet quenching

Look at single particle: π0

Page 16: Richard Seto UCR CSULA – 11/17/2010

Calculations:e ~10-15 GeV/fm3

ecritial ~0.6 GeV/fm3

direct photons scale as Ncoll

p0 suppressed by 5! High density Colored matter

What is the energy density? “Jet quenching”

AuAu 200 GeV

RAA

Direct γ

π0

η0.2

Correction Au=197 nucleons

Energy density is high Enough!

0

0

in AuAu collisions in pp collisions

pp

Page 17: Richard Seto UCR CSULA – 11/17/2010

What about the “other” side?Jet correlations in proton-proton reactions.

Strong back-to-back peaks.

Jet correlations in central Gold-Gold.

Away side jet disappears for particles pT > 2 GeV

Jet correlations in central Gold-Gold.

Away side jet reappears for particles pT>200 MeV

Azimuthal Angular Correlations

Leading hadrons

Medium

Page 18: Richard Seto UCR CSULA – 11/17/2010

Almost complete extinction of jetIs this remarkable? (me-2002) “As you might know, the most interesting

observation made at RHIC is that of the suppression of high-Energy hadrons, which may be an indication of jet quenching.

This is a remarkable effect. It is as if a bullet fired from a 22 rifle were stopped by a piece of tissue paper (actually by weight, the tissue paper would stop a bullet with 1000x the kinetic energy of an ordinary 22 bullet. Is this interesting? Just as a physical phenomena, it certainly seems to me to be quite extraordinary. The stuff that is being created - presumably a QGP is about the most viscous stuff on earth”.

dead wrong

right

Page 19: Richard Seto UCR CSULA – 11/17/2010

Now that we have the Temperature and Energy density… (Serway again)

19

Monotonic Gas (3 degrees of freedom) E=3/2 nRT

Diatomic Gas (3+2=5 degrees of freedom) E=5/2nRT

Degrees of Freedom! (something about what it is…)

Page 20: Richard Seto UCR CSULA – 11/17/2010

24

30g Tpe

Can we melt the hadrons and liberate quark and gluon degrees of freedom?

Energy density for “g” massless d.o.f. (bosons)Stefan Boltzmann law (Serway 17.10)

243

30Tpe

Hadronic Matter: quarks and gluons confinedFor T ~ 200 MeV, 3 pions with spin=0

2437

30Tpe

Quark Gluon Plasma:8 gluons;

2 light quark flavors, antiquarks,

2 spins, 3 colorsd.o.f=37!

a first guess: Degrees of Freedom

72 8 2 2 2 (3) 38s g s a f c

Page 21: Richard Seto UCR CSULA – 11/17/2010

NDOF? a Sanity check - data

2437

30Tpe

2 4

30 30 40NDOFT

ep

243

30Tpe

310 15GeVfm

e ~ 0.300initialT GeV

Regular stuff “QGP”

good… But we really have no idea what the DOF really are

Page 22: Richard Seto UCR CSULA – 11/17/2010

III. Viscosity

Page 23: Richard Seto UCR CSULA – 11/17/2010

Flow, Hydrodynamics, Viscosity, Perfect Fluids….

YUK!

and String Theory

WHAT?!

Los Angles Times – May 2005

Page 24: Richard Seto UCR CSULA – 11/17/2010

The subject of the flow of fluids, and particularly of water, fascinates everybody….

Fluids: Ask Feynman ( from Feynman Lecture Vol II)

Surely you’rejoking

Mr. Feynman

The subject of the flow of fluids, and particularly of water, fascinates everybody….we watch streams, waterfalls, and whirlpools, and we are fascinated by this substance which seems almost alive relative to solids. ….

Page 25: Richard Seto UCR CSULA – 11/17/2010

[ ]

Viscosity and the equation of fluid flow

=density of fluid=potential (e.g. gravitational-think mgh)v=velocity of fluid elementp=pressure Bernoulli Sheer Viscocity

Page 26: Richard Seto UCR CSULA – 11/17/2010

Non-ZERO Viscosity

smoke ring dissipates

[ ]

smoke ring diffuses

Page 27: Richard Seto UCR CSULA – 11/17/2010

[ ]

ZERO Viscosity

smoke ring keeps its shape

note: you actually need viscosity to get the smoke ring started

does not diffuse

Viscosity dissipates momentum

Page 28: Richard Seto UCR CSULA – 11/17/2010

Measuring viscosityFlow: A collective effect

2 2

2 2 2 cos 2x y

x y

p pv

p p

x

yz

Coordinate space: initial asymmetry

pressure

py

px

Momentum space: final asymmetry

28

dn/d ~ 1 + 2 v2(pT) cos (2 ) + ...Initial spatial anisotropy converted into momentum anisotropy. Efficiency of conversion depends on the properties of the medium.

Page 29: Richard Seto UCR CSULA – 11/17/2010

                       

Anisotropic Flow Conversion of spatial anisotropy to

momentum anisotropy depends on viscosity Same phenomena observed in gases of

strongly interacting atoms (Li6)weakly coupledfinite

viscosity

strongly coupled

viscosity=0

The RHIC fluid behaves like this, that is, viscocity~0

M. Gehm, et alScience 298 2179 (2002)

29

Page 30: Richard Seto UCR CSULA – 11/17/2010

Viscocity: Serway again

30

Weakly coupledlarge viscosity

Strongly coupledzero viscosity

Page 31: Richard Seto UCR CSULA – 11/17/2010

Calculating the viscosity (from Feynman)

energy momentum stress tensor

31

Bigger F/A larger viscosityLarger viscosity smaller v0 Larger viscosity can act over larger d

y

xCan we calculate the viscosity ()?BIG problem, QCD in our regime is a strongly coupled theoryPerturbative techniques do NOT work

Einstein field eqn

Page 32: Richard Seto UCR CSULA – 11/17/2010

To the rescue!String theory: Extra Dimensions

“QCD” strong couplingComplicated

Possibility to solve a strongly coupled theory! (for the first time??)

4d Boundary(we live here)

5d bulk theory z

dual

Page 33: Richard Seto UCR CSULA – 11/17/2010

33

An Analogy What is this??

In 3D – Its easy to see

Its a Hologram

Chessmen – a knight, bishop, king

Hmm... lets think. Its in 2D You’re kidding!

dual

Page 34: Richard Seto UCR CSULA – 11/17/2010

using gauge-string duality

σ(0)=area of black hole horizon

“The key observation… is that the right hand side of the Kubo formula is known to be proportional to the classical absorption cross section of gravitons by black holes.”

8 G p

dualGravity

=4 SYM“QCD”strong coupling

Policastro, Son, Starinets hep-th 0104066“QCD” strong coupling

34

Gravity

Page 35: Richard Seto UCR CSULA – 11/17/2010

finishing it up: we want /s (s=entropy)

Entropy black hole “branes”” Entropy

=4 SYM“QCD”Entropy

black hole Bekenstetein, Hawking

= Area of black hole horizon

SYM " "(0)

4GQCDs 1

4 4 Bs k

p p

Kovtun, Son, Starinets hep-th 0405231

=σ(0)

k=8.6 E -5 eV/K

This is believed to be a universal lower bound for a wide class ofGauge theories with a gravity dual

35

In ourUnits

We had 8 G p

Page 36: Richard Seto UCR CSULA – 11/17/2010

Extracting /s from Data

Lo and behold best fit /s ~0.08 = 1/4p

STAR “non-flow” subtracted

36

Phys.Rev.C78:034915 (2008) 

V 2 Pe

rcen

t

Page 37: Richard Seto UCR CSULA – 11/17/2010

cos4 BRHIC

Vis ityEntropy Density kp

sQGP – the most perfect fluid?

lowest viscositypossible?

4sp

helium waternitrogen

viscosity bound?

37

Page 38: Richard Seto UCR CSULA – 11/17/2010

cos4 BRHIC

Vis ityEntropy Density kp

viscocity~0, i.e. A Perfect Fluid?

See “A Viscosity Bound Conjecture”, P. Kovtun, D.T. Son, A.O. Starinets, hep-th/0405231

◦ THE SHEAR VISCOSITY OF STRONGLY COUPLED N=4 SUPERSYMMETRIC YANG-MILLS PLASMA., G. Policastro, D.T. Son , A.O. Starinets, Phys.Rev.Lett.87:081601,2001 hep-th/0104066

lowest viscositypossible?

4sp

helium

waternitrogen

viscosity bound?

Meyer Lattice: /s = 0.134 (33)

RHIC

arXiv:0704.1801

38

14p

Page 39: Richard Seto UCR CSULA – 11/17/2010

Some conclusions/thoughts Observations

◦Ti ~ 300 MeV > Tcritical

◦enormous stopping power energy density ~ 15 GeV/fm3 > critical energy

density ◦Strong flow signal viscosity/entropy density ~ 1/4π Perfect fluid

the stuff we are making at RHIC – sQGP◦Strongly Interacting Quark-Gluon-Plasma◦Interesting new connection String Theory and extra dimensions

Page 40: Richard Seto UCR CSULA – 11/17/2010

Where are we? Like trying to study liquid water on a planet whose

temperature was a couple hundred degrees below 0o C by shooting ice cubes at each other

Some dates Newton 1687, Coulomb 1780 Boyle’s law ~1660 Thermo Otto von GuerickeOtto von Guericke 1650 Fluid dynamics Blaise Pascal (hydrostatics), Daniel Bernoulli (1700).

We have barely got to Boyle’s law ~1660

big future ahead of us – but I have no idea where it will lead. Perhaps sometime – far in the future, we will understand the world of

the strong interaction, as well as we do the world of the electro-magnetic interaction

Page 41: Richard Seto UCR CSULA – 11/17/2010

UCR Physics Grad School Preview

Page 42: Richard Seto UCR CSULA – 11/17/2010

Growth of UCR Physics

1996-97 1997-98 1998-99 1999-00 2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09 2009-10 2010-110

20

40

60

80

100

120

140

Graduate Students

Incoming Grad Students

Faculty

Page 43: Richard Seto UCR CSULA – 11/17/2010

Outstanding Faculty 28 Faculty

– Junior Faculty Awards: 5 NSF Career, 3 DOE Young Investigator,2 Office of Naval Research Young Investigator,1 Sloan

– Senior Awards: 7 American Physical Society Fellows,3 AAAS, 1 Guggenheim, 1 Humboldt, 1 APS Panofsky Prize

US News Graduate Program Rank 2010: 52/187 NRC 2006: 49/161 Overall, 35/161 Research,

19/161 Diversity Annual budget: ~$11M, 4th highest in CNAS Faculty Generated Contract and Grant:

>$7.5M/year in 2009-10, $260K/faculty

Page 44: Richard Seto UCR CSULA – 11/17/2010

Graduate Program Highlights Outstanding Research Opportunities

– For Condensed Matter with UCR Center for Nanoscale Science and

– For Biophysics with UCR’s Biochemistry/Molecular Biology and Bioengineering

– For Environmental Physics with joint MSc program with UCR Environmental Science

– High Energy and Relativistic Heavy Ion Physics programs highly leveraged with international collaborations at LHC, RHIC, SLAC, Fermi Lab

– Astronomy program well-leveraged with UC telescopes (Keck and future TMT), Southern California astronomy infrastructure, and access to SpARCS and COSMOS survey data

Page 45: Richard Seto UCR CSULA – 11/17/2010

Fellowship/TA/GSR packages◦ 1st year Fellowship (academic year + summer) 50% TA (20 h/week) (covers tuition & health)

◦ 2nd year 50% TA (20 h/week) (covers tuition & health) Summer research support through PI (or TA)

◦ 3rd year + TA/GSR (covers tuition & health) Summer research support through PI (or TA)

Application fee will be waived by the graduate division. ◦ Fill out today’s sign-in sheet with full name & birth date or SSN. ◦ Submit application.