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Parity Violation: Past, Present, and Future. 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?

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Nsac long range plan
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 plan1
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


Outline

Outline

  • PVES and Nucleon Structure

  • PVES and Nucleonic Matter

  • PVES and the New Standard Model


Parity violating asymmetry

QPW, GPW

APV APC*

GPW

[

]

QPW+ F(Q2, )

Parity-Violating Asymmetry


Pv electron scattering experiments
PV Electron Scattering Experiments

MIT-Bates

Mainz

SLAC

Jefferson Lab


Pv electron scattering experiments1
PV Electron Scattering Experiments

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

SLAC


Pv electron scattering experiments2
PV Electron Scattering Experiments

MIT-Bates

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


Pv electron scattering experiments3
PV Electron Scattering Experiments

Mainz

QE e 9Be (1980’s) Elastic ep (1990’s - now)


Pv electron scattering experiments4
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


Pves and nucleon structure

Constituent quarks (QM)

Current quarks (QCD)

QP ,P

FP2(x)

PVES and Nucleon Structure

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


Pves and nucleon structure1

PVES and Nucleon Structure

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)


Pves and nucleon structure2

Strange quarks in the nucleon:

  • Sea quarks

  • ms ~ QCD

  • 20% of nucleon mass, possibly -10% of spin

What role in electromagnetic structure ?

PVES and Nucleon Structure

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


We can uncover the sea with g p w

Effects in GP suppressed by

QCD/mq) 4 < 10 -4

QCD ~ 150 MeV

Neglect them

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


We can uncover the sea with g p w1

ms ~ QCD : No suppression

not necessarily negligible

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


We can uncover the sea with g p w2

Lives only in the sea

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


Parity violating electron scattering

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

Parity-Violating Electron Scattering

Kaplan and Manohar McKeown

Neutral Weak Form Factors


Parity violating electron scattering1

Parity-Violating Electron Scattering

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).


Axial radiative corrections

“Anapole” effects : Hadronic Weak Interaction

+

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

Axial Radiative Corrections


Anapole effects

Zhu et al.

Zhu, Puglia, Holstein, R-M (cPT) Maekawa & van Kolck (cPT) Riska (Model)

“Anapole” Effects

Hadronic PV

Can’t account for a large reduction in GeA


Nuclear pv effects

Suppressed by ~ 1000

Nuclear PV Effects

PV 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


Strange quark form factors

Strange Quark Form Factors

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

Js = JB + 2 JEM, I=0



Q 2 dependence of g s m

Happex projected

G0 projected

Lattice QCD theory

Dispersion theory

Chiral perturbation theory “reasonable range” for slope

Q2 -dependenceof GsM


What pt can cannot say

Kaon loop contributions (calculable)

Unknown low-energy constant (incalculable)

What PT can (cannot) say

Ito, R-M Hemmert, Meissner, Kubis Hammer, Zhu, Puglia, R-M

Strange magnetism as an illustration


What pt can cannot say1

NLO, unknown LEC

{

}

LO, parameter free

NLO, cancellation

What PT can (cannot) say

Strange magnetism as an illustration


Dispersion theory gives a model independent prediction

Slope of GMs

Strong interaction scattering amplitudes

e+ e- K+ K-, etc.

Dispersion theory gives a model-independent prediction

Jaffe Hammer, Drechsel, R-M


Dispersion theory gives a model independent prediction1

Perturbation theory (1-loop)

Dispersion theory gives a model-independent prediction

Hammer & R-M


Dispersion theory gives a model independent prediction2

All orders

 resonance

Perturbation theory (1-loop)

Dispersion theory gives a model-independent prediction

Hammer & R-M


Dispersion theory gives a model independent prediction3

Can’t do the whole integral

  • Are there higher mass excitations of s s pairs?

  • Do they enhance or cancel low-lying excitations?

?

Dispersion theory gives a model-independent prediction

Experiment will give an answer


Pves and nucleonic matter
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


Pves and nucleonic matter1

~ 0.1

PVES and Nucleonic Matter

Donnelly, Dubach, Sick

The Z0 boson probes neutron properties

QW = Z(1 - 4 sin2W) - N

Horowitz, Pollock, Souder, & Michels

PREX (Hall A): 208Pb


Pves and neutron stars

PREX

PVES and Neutron Stars

Neutron star

Horowitz & Piekarewicz

208Pb

Crust thickness decreases with Pn

Skin thickness (Rn-Rp) increases with Pn


Pves and neutron stars1
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?


Present universe

Early universe

Standard Model

High energy desert

Weak scale

Planck scale

PVES and the New Standard Model


Present universe

Early universe

Standard Model

High energy desert

Weak scale

Planck scale

PVES and the New Standard Model

A “near miss” for grand unification


Present universe

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


Present universe

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


Neutral current mixing depends on electroweak symmetry

SU(2)L

U(1)Y

Neutral current mixing depends on electroweak symmetry

JmWNC = Jm0 + 4 Q sin2WJmEM


Weak mixing also depends on scale

Standard Model

sin2W

(GeV)

MZ

Weak mixing also depends on scale

Czarnecki & Marciano Erler, Kurylov, R-M


Sin 2 w depends on particle spectrum
sin2W() depends on particle spectrum


Sin 2 w depends on particle spectrum1
sin2W() depends on particle spectrum


Sin 2 w depends on particle spectrum2
sin2W() depends on particle spectrum


New physics parity violation

QeW = -1 + 4 sin2W

QPW = 1 - 4 sin2W

QCsW = Z(1 - 4 sin2W) - N

New Physics & Parity Violation

sin2W is scale-dependent


Weak mixing also depends on scale1

Atomic PV

N deep inelastic

sin2W

e+e- LEP, SLD

SLAC E158

JLab Q-Weak

(GeV)

Weak mixing also depends on scale


Additional symmetries in the early universe can change scale dependence

Fermions

Bosons

sfermions

gauginos

Higgsinos

Charginos, neutralinos

Additional symmetries in the early universe can change scale-dependence

Supersymmetry


Present universe

Early universe

Standard Model

Weak scale

Planck scale

Electroweak & strong couplings unify with supersymemtry

Supersymmetry

Weak scale & GF are protected


Susy will change sin 2 w evolution
SUSY will change sin2W() evolution


Susy will change sin 2 w evolution1
SUSY will change sin2W() evolution


Comparing q w e and q w p

SUSY loops

Comparing Qwe and QWp

Kurylov, R-M, Su

SUSY loops

3000 randomly chosen SUSY parameters but effects are correlated


Can susy explain dark matter
Can SUSY explain dark matter?

Expansion

Rotation curves

Cosmic microwave background


Susy provides a dm candidate

e.g.

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


B and or l violation in susy can also affect low energy weak interactions

12k

1j1

12k

1j1

B and/or L Violation in SUSY can also affect low-energy weak interactions

L=1

L=1

QPW in PV electron scattering

-decay, -decay,…


Comparing q w e and q w p1

SUSY loops

 SUSY dark matter

->e+e

RPV 95% CL

Comparing Qwe and QWp

Kurylov, R-M, Su

n is Majorana


Comparing q w e and q w p2
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.


Weak mixing also depends on scale2

Atomic PV

N deep inelastic

DIS-Parity, JLab

DIS-Parity, SLAC

sin2W

e+e- LEP, SLD

SLAC E158

JLab Q-Weak

Moller, JLab

(GeV)

Weak mixing also depends on scale


Comparing q w e and q w p3

SUSY loops

E158 &Q-Weak

JLab Moller

RPV 95% CL

Comparing Qwe and QWp

Kurylov, R-M, Su

 SUSY dark matter


Interpretation of precision measurements

Form factors: MIT, JLab, Mainz

Weak charge

Q2=0.03 (GeV/c)2

Q2>0.1 (GeV/c)2

Interpretation of precision measurements

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

Proton Weak Charge


Interpretation of precision measurements1
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
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


Qcd effects in q w p

Box graphs

QW ~ 26%

QW ~ 3%

QW ~ 6%

kloop ~ MW :pQCD

QCD Effects in QWP

QCD < kloop < MW :non-perturbative


Box graphs cont d

Protected by symmetry

Short-distance correction: OPE

QWp(QCD) ~ -0.7% WW

QWp(QCD) ~ -0.08% ZZ

Box graphs, cont’d.


Box graphs cont d1

+

Long-distance physics: not calculable

[

]

ln

Fortuitous suppression factor: box + crossed ~ kJJZ ~ Agve = (-1+4 sin2W)

Box graphs, cont’d.


Neutron decay

[

]

ln

|CW|<2 to avoid exacerbating CKM non-unitarity

|CZ|<2 QWp <1.5%

Neutron-decay


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