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Parity Violation: Past, Present, and FuturePowerPoint Presentation

Parity Violation: Past, Present, and Future

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### Parity Violation: Past, Present, and Future

### Outline

### PVES and Nucleon Structure

### PVES and Nucleon Structure

### PVES and Nucleon Structure

### Parity-Violating Electron Scattering

### Parity-Violating Electron Scattering

### Strange Quark Form Factors

M.J. Ramsey-Musolf

NSAC Long Range Plan

- What is the structure of the nucleon?
- What is the structure of nucleonic matter?
- What are the properties of hot nuclear matter?
- What is the nuclear microphysics of the universe?
- What is to be the new Standard Model?

NSAC Long Range Plan

- What is the structure of the nucleon?
- What is the structure of nucleonic matter?
- What are the properties of hot nuclear matter?
- What is the nuclear microphysics of the universe?
- What is to be the new Standard Model?

Parity-Violating Electron Scattering

- PVES and Nucleon Structure
- PVES and Nucleonic Matter
- PVES and the New Standard Model

PV Electron Scattering Experiments

Deep Inelastic eD (1970’s) PV Moller Scattering (now) Deep Inelastic eD (2005?)

SLAC

PV Electron Scattering Experiments

MIT-Bates

Elastic e 12C (1970’s - 1990) Elastic ep, QE eD (1990’s - now)

PV Electron Scattering Experiments

Elastic ep: HAPPEX, G0 (1990’s - now) Elastic e 4He: HAPPEX (2003) Elastic e 208Pb: PREX QE eD, inelastic ep: G0 (2003-2005?) Elastic ep: Q-Weak (2006-2008) Moller, DIS eD (post-upgrade?)

Jefferson Lab

Current quarks (QCD)

QP ,P

FP2(x)

What are the relevant degrees of freedom for describing the properties of hadrons and why?

Why does the constituent Quark Model work so well?

- Sea quarks and gluons are “inert” at low energies
- Sea quark and gluon effects are hidden in parameters and effective degrees of freedom of QM (Isgur)
- Sea quark and gluon effects are hidden by a “conspiracy” of cancellations (Isgur, Jaffe, R-M)
- Sea quark and gluon effects depend on C properties of operator (Ji)

Strange quarks in the nucleon:

- Sea quarks
- ms ~ QCD
- 20% of nucleon mass, possibly -10% of spin

What role in electromagnetic structure ?

What are the relevant degrees of freedom for describing the properties of hadrons and why?

Effects in GP suppressed by

QCD/mq) 4 < 10 -4

QCD ~ 150 MeV

Neglect them

We can uncover the sea with GPWLight QCD quarks:

u mu ~ 5 MeV

d md ~ 10 MeV

s ms ~ 150 MeV

Heavy QCD quarks:

c mc ~ 1500 MeV

b mb ~ 4500 MeV

t mt ~ 175,000 MeV

ms ~ QCD : No suppression

not necessarily negligible

We can uncover the sea with GPWLight QCD quarks:

u mu ~ 5 MeV

d md ~ 10 MeV

s ms ~ 150 MeV

Heavy QCD quarks:

c mc ~ 1500 MeV

b mb ~ 4500 MeV

t mt ~ 175,000 MeV

We can uncover the sea with GPW

Light QCD quarks:

u mu ~ 5 MeV

d md ~ 10 MeV

s ms ~ 150 MeV

Heavy QCD quarks:

c mc ~ 1500 MeV

b mb ~ 4500 MeV

t mt ~ 175,000 MeV

GP = QuGu + QdGd+ QsGs

Gn = QuGd + QdGu+ QsGs, isospin

GPW = QuWGu + QdWGd+ QsWGsZ0

SAMPLE (MIT-Bates), HAPPEX (JLab), PVA4 (Mainz), G0 (JLab)

Gu , Gd , Gs

Kaplan and Manohar McKeown

Neutral Weak Form Factors

Separating GEW , GMW , GAW

GMW , GAW SAMPLE

GMW , GEW HAPPEX, PVA4

GMW , GEW , GAW : Q2-dependence G0

Published results: SAMPLE, HAPPEX

Models for s

Radiative corrections

at Q2=0.1 (GeV/c)2

- s-quarks contribute less than 5% (1s) to the proton’s magnetic form factor.
- proton’s axial structure is complicated!

R. Hasty et al., Science 290, 2117 (2000).

“Anapole” effects : Hadronic Weak Interaction

+

Nucleon Green’s Fn : Analogous effects in neutron -decay, PC electron scattering…

Axial Radiative CorrectionsZhu, Puglia, Holstein, R-M (cPT) Maekawa & van Kolck (cPT) Riska (Model)

“Anapole” EffectsHadronic PV

Can’t account for a large reduction in GeA

Suppressed by ~ 1000

Nuclear PV EffectsPV NN interaction

Carlson, Paris, Schiavilla Liu, Prezeau, Ramsey-Musolf

D2

200 MeV data

Mar 2003

H2

Zhu, et al.

Radiative corrections

SAMPLE Results

R. Hasty et al., Science 290, 2117 (2000).

atQ2=0.1 (GeV/c)2

- s-quarks contribute less than 5% (1s) to the proton’s magnetic moment.

200 MeV update 2003:

Improved EM radiative corr.

Improved acceptance model

Correction for p background

125 MeV:

no p background

similar sensitivity

to GAe(T=1)

E. Beise, U Maryland

Theoretical Challenge:

- Strange quarks don’t appear in Quark Model picture of the nucleon

- Perturbation theory may not apply

QCD / ms ~ 1 No HQET

mK / c ~ 1/2 PT ?

- Symmetry is impotent

Js = JB + 2 JEM, I=0

G0 projected

Lattice QCD theory

Dispersion theory

Chiral perturbation theory “reasonable range” for slope

Q2 -dependenceof GsMKaon loop contributions (calculable)

Unknown low-energy constant (incalculable)

What PT can (cannot) sayIto, R-M Hemmert, Meissner, Kubis Hammer, Zhu, Puglia, R-M

Strange magnetism as an illustration

{

}

LO, parameter free

NLO, cancellation

What PT can (cannot) sayStrange magnetism as an illustration

Strong interaction scattering amplitudes

e+ e- K+ K-, etc.

Dispersion theory gives a model-independent predictionJaffe Hammer, Drechsel, R-M

resonance

Perturbation theory (1-loop)

Dispersion theory gives a model-independent predictionHammer & R-M

- Are there higher mass excitations of s s pairs?
- Do they enhance or cancel low-lying excitations?

?

Dispersion theory gives a model-independent predictionExperiment will give an answer

PVES and Nucleonic Matter

What is the equation of state of dense nucleonic matter?

We know a lot about the protons, but lack critical information about the neutrons

~ 0.1

PVES and Nucleonic MatterDonnelly, Dubach, Sick

The Z0 boson probes neutron properties

QW = Z(1 - 4 sin2W) - N

Horowitz, Pollock, Souder, & Michels

PREX (Hall A): 208Pb

PVES and Neutron Stars

Neutron star

Horowitz & Piekarewicz

208Pb

Crust thickness decreases with Pn

Skin thickness (Rn-Rp) increases with Pn

PVES and Neutron Stars

Horowitz & Piekarewicz

Neutron star properties are connected to density-dependence of symmetry energy

PREX probes Rn-Rp a meter of E ( r )

PVES and the New Standard Model

We believe in the Standard Model, but it leaves many unanswered questions

- What were the symmetries of the early Universe and how were they broken?
- What is dark matter?
- Why is there more matter than anti-matter?

Early universe

Standard Model

High energy desert

Weak scale

Planck scale

PVES and the New Standard Model

Early universe

Standard Model

High energy desert

Weak scale

Planck scale

PVES and the New Standard Model

A “near miss” for grand unification

Early universe

Standard Model

High energy desert

Weak scale

Planck scale

PVES and the New Standard Model

Weak scale is unstable against new physics in the desert

GF would be much smaller

Early universe

Standard Model

High energy desert

Weak scale

Planck scale

PVES and the New Standard Model

Not enough CP-violation for weak scale baryogenesis

U(1)Y

Neutral current mixing depends on electroweak symmetryJmWNC = Jm0 + 4 Q sin2WJmEM

sin2W

(GeV)

MZ

Weak mixing also depends on scaleCzarnecki & Marciano Erler, Kurylov, R-M

sin2W() depends on particle spectrum

sin2W() depends on particle spectrum

sin2W() depends on particle spectrum

QeW = -1 + 4 sin2W

QPW = 1 - 4 sin2W

QCsW = Z(1 - 4 sin2W) - N

New Physics & Parity Violationsin2W is scale-dependent

N deep inelastic

sin2W

e+e- LEP, SLD

SLAC E158

JLab Q-Weak

(GeV)

Weak mixing also depends on scaleBosons

sfermions

gauginos

Higgsinos

Charginos, neutralinos

Additional symmetries in the early universe can change scale-dependenceSupersymmetry

Early universe

Standard Model

Weak scale

Planck scale

Electroweak & strong couplings unify with supersymemtry

Supersymmetry

Weak scale & GF are protected

SUSY will change sin2W() evolution

SUSY will change sin2W() evolution

Comparing Qwe and QWp

Kurylov, R-M, Su

SUSY loops

3000 randomly chosen SUSY parameters but effects are correlated

SUSY provides a DM candidate

Neutralino

- Stable, lightest SUSY particle if baryon (B) and lepton (L) numbers are conserved

- However, B and L need not be conserved in SUSY, leading to neutralino decay

12k

1j1

12k

1j1

B and/or L Violation in SUSY can also affect low-energy weak interactionsL=1

L=1

QPW in PV electron scattering

-decay, -decay,…

SUSY dark matter

->e+e

RPV 95% CL

Comparing Qwe and QWpKurylov, R-M, Su

n is Majorana

Comparing Qwe and QWp

- Can be a diagnostic tool to determine whether or not
- the early Universe was supersymmetric
- there is supersymmetricdark matter

The weak charges can serve a similar diagnostic purpose for other models for high energy symmetries, such as left-right symmetry, grand unified theories with extra U(1) groups, etc.

N deep inelastic

DIS-Parity, JLab

DIS-Parity, SLAC

sin2W

e+e- LEP, SLD

SLAC E158

JLab Q-Weak

Moller, JLab

(GeV)

Weak mixing also depends on scaleE158 &Q-Weak

JLab Moller

RPV 95% CL

Comparing Qwe and QWpKurylov, R-M, Su

SUSY dark matter

Form factors: MIT, JLab, Mainz

Weak charge

Q2=0.03 (GeV/c)2

Q2>0.1 (GeV/c)2

Interpretation of precision measurementsHow well do we now the SM predictions? Some QCD issues

Proton Weak Charge

Interpretation of precision measurements

How well do we now the SM predictions? Some QCD issues

Proton Weak Charge

FP(Q2, -> 0) ~ Q2

Use PT to extrapolate in small Q2 domain and current PV experiments to determine LEC’s

Summary

- Parity-violating electron scattering provides us with a well-understood tool for studying several questions at the forefront of nuclear physics, particle physics, and astrophysics:
- Are sea quarks relevant at low-energies?
- How compressible is neutron-rich matter
- What are the symmetries of the early Universe?

- Jefferson Lab is the parity violation facility
- We have much to look forward to in the coming years

QW ~ 26%

QW ~ 3%

QW ~ 6%

kloop ~ MW :pQCD

QCD Effects in QWPQCD < kloop < MW :non-perturbative

Short-distance correction: OPE

QWp(QCD) ~ -0.7% WW

QWp(QCD) ~ -0.08% ZZ

Box graphs, cont’d.Long-distance physics: not calculable

[

]

ln

Fortuitous suppression factor: box + crossed ~ kJJZ ~ Agve = (-1+4 sin2W)

Box graphs, cont’d.
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