Parity-Violation with Electrons: Theoretical Perspectives M.J. Ramsey-Musolf

PV: Past, Present, & Future 1970’sSLAC DISStandard Model Atomic PVsin 2  W ~ 10% 1980’sMainz 8 BePV eq couplings MIT 12 C ~ 10% Prehistory

PV: Past, Present, & Future 2000’sSLAC MollerStandard Model & beyond JLabQWeaksin 2  W < 1% APVAnapole moment JLabG A N  MainzHWI (  S=0): d   A  VVCS: A n 1990’sMITG s E,M ~ few % JLabG A & rad corrections Mainz  n (r) APV sin 2  W ~ 1% Anapole moment Modern Era

2010’sJLabDIS-ParityStandard Model & beyond Moller (2)sin 2  W < 1% 2020’sNLCMoller (3) sin 2  W < 0.1% Future PV: Past, Present, & Future

Quarks, Gluons, & the Light Elements How does QCD make hadronic matter? qq Mesons L = Hybrids exotic nonets PV & strange quarks Gluonic effects GPD’s: “Wigner Distributions” (X. Ji) Pentaquark,   m q -dependence of nuclear properties Lattice QCD

Strange Quarks in the Nucleon: What have we learned? Effects in are much less pronounced than in, Jaffe ‘89 Hammer, Meissner, Drechsel ‘95 Dispersion Relations Narrow Resonances High Q 2 ansatz OZI violation

Strange Quarks in the Nucleon: What have we learned? Effects in are much less pronounced than in, HAPPEX SAMPLE

Strange Quarks in the Nucleon: What have we learned? Strange quarks don’t appear in Quark Model picture of the nucleon Perturbation theory may not apply  QCD / m s ~ 1No HQET m K /   ~ 1/2  PT ? Symmetry is impotent J  s = J  B + 2 J  EM, I=0 Unknown constants Theory: how do we understand dynamics of small ss effects in vector current channel ? Challenge to understand QCD at deep, detailed level

Q 2 -dependence of G s M G 0 projected Dispersion theory Chiral perturbation theory “reasonable range” for slope SAMPLE 2003 Happex projected Lattice QCD theory

Lattice Computations Dong, Liu, & Williams (1998)Lewis, Wilcox, Woloshyn (2003) Quenched QCD Wilson fermions 2000 gauge configurations 60-noise estimate/config Quenched QCD Wilson fermions 100 gauge configurations 300-noise estimate/config See also Leinweber et al

Lattice Computations Lattice calculation Charge symmetry Measured octet m.m.’s Chiral symmetry Unquenching Leinweber et al

What  PT can (cannot) say Strange magnetism as an illustration Unknown low- energy constant (incalculable) Kaon loop contributions (calculable) Ito, R-M Hemmert, Meissner, Kubis Hammer, Zhu, Puglia, R-M

What  PT can (cannot) say Strange magnetism as an illustration { } LO, parameter freeNLO, cancellation NLO, unknown LEC

Dispersion theory Strong interaction scattering amplitudes e+ e - K + K -, etc. Slope of G M s Jaffe Hammer, Drechsel, R-M

Perturbation theory (1-loop) Hammer & R-M Dispersion theory All orders

 resonance Perturbation theory (1-loop) Hammer & R-M All orders Dispersion theory S-quarks are not inert Non-perturbative effects dominate (LEC’s)

Are there higher mass excitations of s s pairs? Do they enhance or cancel low-lying excitations? Can’t do the whole integral ? Dispersion theory Models & exp’t suggest cancellations Experiment & lattice will give an answer

Combining  PT, dispersion theory, & lattice QCD RARA “Reasonable range”: lattice & disp rel SAMPLE

Radiative Corrections & the Hadronic Weak Interaction G A e N !  PV  photo- and electro-production (threshold) Vector analyzing power (  )

at Q 2 =0.1 (GeV/c) 2 R. Hasty et al., Science 290, 2117 (2000). s-quarks contribute less than 5% (1  ) to the proton’s magnetic form factor. proton’s axial structure is complicated! Models for  s Radiative corrections

Axial Radiative Corrections “Anapole” effects : Hadronic Weak Interaction + Nucleon Green’s Fn : Analogous effects in neutron  -decay, PC electron scattering…

“Anapole” Effects Zhu, Puglia, Holstein, R-M (  PT) Maekawa & van Kolck (  PT) Riska (Model) Zhu et al. Hadronic PV Can’t account for a large reduction in G e A

Nuclear PV Effects PV NN interaction Carlson, Paris, Schiavilla Liu, Prezeau, Ramsey-Musolf Suppressed by ~ 1000

at Q 2 =0.1 (GeV/c) MeV: no  background similar sensitivity to G A e (T=1) SAMPLE Results R. Hasty et al., Science 290, 2117 (2000). 200 MeV update 2003: Improved EM radiative corr. Improved acceptance model Correction for  background s-quarks contribute less than 5% (1  ) to the proton’s magnetic moment. 200 MeV data Mar 2003 D2D2 H2H2 Zhu, et al. E. Beise, U Maryland Radiative corrections

Transition Axial Form Factor Off Diagonal Goldberger-Treiman Relation Zhu, R-M O (p 2 ) chiral corrections ~ few %  N !  N ~ 5% Rad corrections, “anapole” ~ 25% Study G A N  (Q 2 )/ G A N  (0)

Measuring G A N  (Q 2 ) G A N  & “d  ”” ”  Axial response, G A N  only A LR ~ Q 2 (1-2sin 2  W ) Zhu, Maekawa, Sacco, Holstein, R-M Nonzero A LR (Q 2 = 0)

Weak interactions of s-quarks are puzzling Hyperon weak decays S-Wave: Parity-violating P-Wave: Parity- conserving  symmetry not sufficient

Weak interactions of s-quarks are puzzling M1 (PC) E1 (PV) Th’y Exp’t

Weak interactions of s-quarks are puzzling Resonance saturation Holstein & Borasoy S 11 Roper S-Wave P-Wave Fit matrix elements

Weak interactions of s-quarks are puzzling Resonance saturation Holstein & Borasoy S 11 Roper S-Wave P-Wave Fit matrix elements S/P wave fit Close gap with  BB’

Weak interactions of s-quarks are puzzling Natural Fit Is deviation from QCD-based expectations due to presence of s-quarks or more fundamental dynamics?

We have a  S=0 probe Use PV to filter out EM transition Zhu, Maekawa, Holstein, MR-M PV, E1 Amplitude PV Asymmetry Large N C, spin-flavor SU(4) Finite N C Low energy constant

We have a  S=0 probe Naïve dimensional analysis (NDA) Resonance saturation d  ~ g  d  ~ 25g 

Measuring d  d  = 100 g  enhanced H W  S=0 d  = 0, G A N  only A LR ~ Q 2 (1-2sin 2  W ) Zhu, Maekawa, Sacco, Holstein, R-M

N!  Transition Measure Q 2 -dependence of A LR to learn d  G A N   Q 2 )/ G A N   0) R A  MINERVA: G A N  (0) ?

Vector Analyzing Power T-odd, P-even correlation Doubly virtual compton scattering (VVCS): new probe of nucleon structure Implications for radiative corrections in other processes: G E p /G M p,  -decay… SAMPLE, Mainz, JLab experiments What specifically could we learn? V ud

Vector Analyzing Power + V=  : VVCS Re M   ( M  box  M  cross )Rosenbluth Im M   M  box VAP V=W,Z: Electroweak VVCS Re M V  ( M V  box  M V  cross )  -decay, R A,… Im M V  M V  box  -decay T-violation Direct probe

Vector Analyzing Power Mott: M N !1 SAMPLE EFT to O (p 2 ) Diaconescu, R-M  I=1, r 2 O (p 0 ) O (p 4 )  146 0

Vector Analyzing Power Constrained by SAMPLE  30 0 Dynamical  ’s?

Radiative Corrections & the Hadronic Weak Interaction G A e N !  PV  photo- and electro-production (threshold) Vector analyzing power (  ) Theory for R A good to ~ 25% Further test of R A   d  & H W qq EFT for low energy good to ~ 25%; more tests! New window on electroweak VVCS:  -decay, sin 2  W,…

Weak Mixing Angle: Scale Dependence sin 2  W  (GeV) SLAC E158 (ee)JLab Q-Weak (ep) e + e - LEP, SLD Atomic PV N deep inelastic Czarnecki, Marciano Erler, Kurylov, MR-M

Comparing Q w e and Q W p   -> e  + e  SUSY dark matter is Majorana RPV 95% CL fit to weak decays, M W, etc. Kurylov, Su, MR-M SUSY loops

Comparing Q w e and Q W p Erler, Kurylov, R-M Q W P = Q W e = Experiment SUSY Loops E 6 Z / boson RPV SUSY Leptoquarks SM

sin 2  W  (GeV) SLAC E158 (ee)JLab Q-Weak (ep) e + e - LEP, SLD Atomic PV N deep inelastic Additional PV electron scattering ideas DIS-Parity, JLab Moller, JLab DIS-Parity, SLAC Czarnecki, Marciano Erler et al. Linear Collider e - e -

Comparing Q w e and Q W p  SUSY dark matter Kurylov, R-M, Su SUSY loops RPV 95% CL E158 &Q- Weak JLab Moller Linear collider

Comparing A d DIS and Q w p,e e p RPV Loops SUSY effects

Comparing Q w e and Q W p  SUSY dark matter Kurylov, R-M, Su SUSY loops RPV 95% CL E158 &Q- Weak JLab Moller Linear collider “DIS Parity”

Higher Twist “Pollution” E=11 GeV  = Different PDF fits Sacco, R-M preliminary ~0.4%

Higher Twist “Pollution” Castorina & Mulders Sacco & R-M preliminary Open issues QCD evolution Double handbag Moment inversion

Tasks for the “modern era” & future Strange quarks Finish the experimental program Credible, unquenched lattice calculations Rad corrections Further tests of electroweak VVCS with N! , VAP Theory: quark mass (m  ) dependence Measure d  SM & new physics DIS-Parity: Is there significant I-violation as suggested by NuTeV? Theory: how big is twist pollution? Theory: relating  n (r) & APV Hardronic PV Lots of new exp’t & theory….