January 30, 2004UR PAS GRTS1 Intro to Particle and Nuclear Physics and the Long Island Gold Rush Steven Manly Univ. of Rochester REU seminar June 9, 2004

January 30, 2004UR PAS GRTS 1

Intro to Particle and Nuclear

Physics and the Long Island Gold

Rush

Steven ManlyUniv. of Rochester

REU seminarJune 9, 2004

[email protected]://hertz.pas.rochester.edu/smanly/



Inquiring minds want to know ...

Yo! What holds it together?



What forces exist in nature?

What is a force?

How do forces change with energy or temperature?

How has the universe evolved?

How do they interact?


The fundamental nature of forces: virtual particles

Et h Heisenberg E = mc2 Einstein

e-


Force Source Range StrengthGravitation mass infinite 10-39

Electromagnetism Electriccharge

infinite 10-2

Strong nuclear Colorcharge

10-15 m 1

Weak nuclear Weakcharge

10-18 m 10-5


quarks leptonsGauge bosons

u c t

d s b

e

e

W, Z, , g, Gg

Hadrons

Baryons qqq qq mesons

p = uud

n = udd

K = us or us

= ud or ud

Strong interaction

nuclei

e

atomsElectromagnetic

interaction


Quantum Chromodynamics - QCD

Similar to QED … But ... Gauge field carries the charge

q q

distance

energy density, temperature

rela

tive

stre

ngth

asymptotic freedom

qq qq

confinement

q qqq


Why do we believe QCD is a good description of the strong interaction?

No direct observation of quarks: confinement



Deep inelastic scattering: There are quarks.

From D.H. Perkins, Intro. to High Energy Physics

nucleon

parton

P

Px



ee

qqhadronseeR

)(

P. Burrows, SLAC-PUB7434, 1997

R. Marshall, Z. Phys. C43 (1989) 595

Need the “color” degree of freedom



Event shapes

e+e- Zo qq e+e- Zo qqg



Measure the coupling

P. Burrows, SLAC-PUB7434, 1997


Strong interaction is part of our heritage


Chiral symmetry breaking: the “other” source of mass

qq

qq qq

qq

qq

qq

q

QCD vacuum

Quark condensate

A naïve view …

Strongly interacting particles interact with the vacuum condensate … which makes them much

heavier than the constituent quark masses.



Relativistic heavy ions

•Two concentric superconducting magnet rings, 3.8 km circum.

•A-A (up to Au), p-A, p-p collisions, eventual polarized protons

•Funded by U.S. Dept. of Energy $616 million

•Construction began Jan. 1991, first collisions June 2000

•Annual operating cost $100 million

•AGS: fixed target, 4.8 GeV/nucleon pair

•SPS: fixed target, 17 GeV/nucleon pair

•RHIC: collider, 200 GeV/nucleon pair

•LHC: collider, 5.4 TeV/nucleon pair


The view from above

January 30, 2004UR PAS GRTS 20STAR


Au-Au collision in the STAR detector


Isometric of PHENIX Detector


Brahms experiment

From F.Videbœk


The PHOBOS Detector (2001)

Ring Counters

Time of Flight

Spectrometer

• 4 Multiplicity Array

- Octagon, Vertex & Ring Counters• Mid-rapidity Spectrometer• TOF wall for high-momentum PID• Triggering

- Scintillator Paddles Counters- Zero Degree Calorimeter (ZDC)

Vertex

Octagon

ZDC

z

yx

Paddle Trigger Counter

Cerenkov

1m

137000 silicon pad readout channels


Central Part of the Detector

(not to scale)

0.5m


Au-Au event in the PHOBOS detector


The goals Establish/characterize the expected QCD deconfinement phase transition

quarks+gluons hadrons

Establish/characterize changes in the QCD vacuum at high energies: chiral symmetry restoration and/or disoriented chiral condensates

Understand the nuclear eqn. of state at high energy density

Polarized proton physics


Beamline

Terminology: angles


Beamline

Terminology: anglesPseudorapidity = = Lorentz invariant

angle with repect to the beampipe

0

+1

+2

+3

-1

-2

-3


Terminology: angles = azimuthal angle about the beampipe

Beamline


“Spectators”

Zero-degreeCalorimeter

“Spectators”

Paddle Counter

peripheral collisions central collisions

Nch

Npart

6%

Terminology: centrality

Thanks to P. Steinberg for constructing much of this slide

“Participants”


Signatures/observables

Energy density or number of participants

Measured value

Strange particle enhancement and particle yields

Temperature

J/ and ’ production/suppression

Vector meson masses and widths

identical particle quantum correlations

DCC - isospin fluctuations

Flow of particles/energy (azimuthal asymmetries)

jet quenching

Each variable has different experimental systematics and model dependences on extraction and interpretation

MUST CORRELATE VARIABLES


RHIC operation

12 June, 2000: 1st Collisions @ s = 56 AGeV

24 June, 2000: 1st Collisions @ s = 130 AGeV

July 2001: 1st Collisions @ s = 200 AGeV

Dec. 23, 2002: 1st d-Au collisions @ s = 200 AGeV

Dec. 2004: Au-Au Collisions @ s = 200 AGeV

Run 1

Run 2Run 3

Peak Au-Au luminosity = 5x1026 cm-2s-1

Design Au-Au luminosity = 2x1026 cm-2s-1

Ave luminosity for last week of ‘02 run = 0.4x1026 cm-2s-1

Run 2:

Run 4


PHOBOS Data on dN/din Au+Auvs Centrality and s

dN

/d

19.6 GeV 130 GeV 200 GeVPreliminary

PHOBOS PHOBOS PHOBOS

Typical systematic band (90%C.L.)

Basic systematics of particle production


“Flow” = patterns in the energy, momentum, or particle density distributions that we use to ferret out clues as to the nature of the collision/matter

Reaction plane

x

z

y M. Kaneta

To what extent is the initial geometric

asymmetry mapped into the final state?


Collision region is an extruded football/rugby ball shape

CentralPeripheral


(reaction plane)

Flow quantifiedFlow quantified

dN/d(R ) = N0 (1 + 2V1cos (R) + 2V2cos (2(R) + ... )


(reaction plane)


Directed flow



(reaction plane)


Elliptic flow



(reaction plane)


Higher terms



b (reaction plane)


Flow as an experimental probeFlow as an experimental probe

Sensitive to interaction length/cross section/degree of thermalization

Sensitive to very early times and particle velocities since asymmetry is self-quenching

Probes longitudinal uniformity


Elliptic Flow at 130 GeV

Phys. Rev. Lett. 89 222301 (2002)

(PHOBOS : Normalized Paddle Signal)

Hydrodynamic limit

STAR: PRL86 (2001) 402

PHOBOS preliminary

Hydrodynamic limit

STAR: PRL86 (2001) 402

PHOBOS preliminary

Thanks to M. Kaneta


Flow vs Pt and Hydro describes low pt vs.

particle mass, fails at high pt and high-

T. Hirano

(consider velocity and early, self-quenching asymmetry)


Spectra

0.2<y<1.4

The fun starts when one

compares this to pp spectra

STAR results, shown at QM02


– Production of high pT particles dominated by hard scattering

– High pT yield prop. to Ncoll

(binary collision scaling)

– Compare to pp spectra scaled up by Ncoll

– Violation of Ncoll scaling

– Jet quenching?

Comparing Au+Au and pp Spectra_

_

Au+Au


Suppression in Hadron Spectra

Shown by T. Peltzmann at QM02


Jet-quenching: hard parton interacts with medium, which softens the momentum spectrum in A-A relative to pp


Peripheral Au+Au data vs. pp+flow

STAR, David Hartke - shown at QM02

Count tracks around very high pT particle


Central Au+Au data vs. pp+flow

STAR, David Hartke - shown at QM02

Away side jet disappears!!


Jet-quenching also gives break in flow vs. pT


Initial state vs. final state effects

Jet-quenching is a final state effect - “Weisaker-Williams” color field of parton interacting with colored medium. Energy loss is medium-size dependent (radiated wavelengths less than source size)

Initial state effect - saturation models color glass condensate (recent review: Iancu, Leonidov, McLerran, hep-ph/0202270)

can also qualitatively explain some features of the data


d-Au data


Molnar and Voloshin, nucl-th/0302014

Partonic energy loss alone leads drop at very large pT and does not account for meson/baryon differences

Quark coalescence vs. fragmentationQuark coalescence vs. fragmentation

nucl-ex/0306007nucl-ex/0305013


Xhangbu Xu, Quark Matter 2004

QuarkQuark coalescence-NCQ scalingcoalescence-NCQ scaling

’s affected by resonance decays? Dong, Esumi, Sorensen, N.Xu, Z,Xu, nucl-th/0403030


Showed you too much - I apologize

Showed you too little - I apologize

What are the lessons?

RHIC/experiments running very well

Up till now …

characterization and refinement of models


Hot, dense, opaque medium is formed

Energy density above lattice predictions for deconfined state

Local thermal equilibrium achieved

Full 3-d structure away from mid-rapidity not yet understood

Interesting signals being pursued … jet-quenching?

QM2004: It probably is a duck!

Remains to be seen if systematic study and pursuit of the surprises leads to anything beyond the duck!

Future = statistics (J/+ more), vary species/energies, LHC

Is it a duck?



Documents

January 30, 2004UR PAS GRTS1 Intro to Particle and Nuclear Physics and the Long Island Gold Rush Steven Manly Univ. of Rochester REU seminar June 9, 2004