Parity-Violation with Electrons: Theoretical Perspectives M.J. Ramsey-Musolf.
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Transcript of Parity-Violation with Electrons: Theoretical Perspectives M.J. Ramsey-Musolf.
Parity-Violation with Electrons: Theoretical Perspectives
M.J. Ramsey-Musolf
PV: Past, Present, & Future
1970’s SLAC DIS Standard ModelAtomic PV sin2W ~ 10%
1980’s Mainz 8Be PV eq couplingsMIT 12C ~ 10%
Prehistory
PV: Past, Present, & Future
2000’s SLAC Moller Standard Model & beyondJLab QWeak sin2W < 1%APV Anapole moment
JLab GAN
Mainz HWI (S=0): dA
VVCS: An
1990’s MIT GsE,M ~ few %
JLab GA & rad correctionsMainz n(r)APV sin2W ~ 1%
Anapole moment
Modern Era
2010’s JLab DIS-Parity Standard Model & beyondMoller (2) sin2W < 1%
2020’s NLC Moller (3) sin2W < 0.1%
Future
PV: Past, Present, & Future
Quarks, Gluons, & the Light Elements
How does QCD make hadronic matter?
1.0
1.5
2.0
2.5
qq Mesons
L = 01 2 3 4H
ybrids
exoticnonets
PV & strange quarks
Gluonic effects
GPD’s: “Wigner Distributions” (X. Ji)
Pentaquark,
mq-dependence of nuclear properties
Lattice QCD
Strange Quarks in the Nucleon:What have we learned?
Effects in are much less pronounced than in ,
€
N s γ μ s N
€
N s s N
€
N s γ μγ 5s N
Jaffe ‘89
Hammer, Meissner, Drechsel ‘95
• Dispersion Relations• Narrow Resonances• High Q2 ansatz
OZI violation
€
gφNN
gωNN
≈1
2
Strange Quarks in the Nucleon:What have we learned?
Effects in are much less pronounced than in ,
€
N s γ μ s N
€
N s s N
€
N s γ μγ 5s N
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 / ms ~ 1 No HQET
mK / ~ 1/2 PT ?
• Symmetry is impotent
Js = J
B + 2 JEM, 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
Q2 -dependenceof Gs
M
G0 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
€
s = Fμ p
u
μ Σu , μ s
μ dloop( )
Lattice calculation
• Charge symmetry• Measured octet m.m.’s• Chiral symmetry• Unquenching
€
s ≈ −0.05 ± 0.02
Leinweber et al
What PT can (cannot) say
Strange magnetism as an illustration
GMs (qs) = μs + 1
6 q2 rs,M2 +L
μs = 2MN Λ χ( ) bs + L
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
GMs (qs) = μs + 1
6 q2 rs,M2 +L
rs,M2 =−
6Λχ
2MN
Λχ
⎛
⎝ ⎜
⎞
⎠ ⎟ bs
r
+118
(5D2 −6DF +9F2)πMN
mK
+7lnmK
μ
⎛
⎝ ⎜ ⎞
⎠ ⎟ +L
{}
LO, parameter free NLO, cancellation
NLO, unknown LEC
Dispersion theory
rs,M2 =
6π
dtImGM
s (t)t2
9mπ2
∞
∫
Strong interaction scattering amplitudes
e+ e- K+ K-, etc.
Slope of GMs
Jaffe Hammer, Drechsel, R-M
rs,M2 =
6π
dtImGM
s (t)t2
4mK2
∞
∫
Perturbation theory (1-loop)€
€
K +
Hammer & R-MDispersion theory
All orders
rs,M2 =
6π
dtImGM
s (t)t2
4mK2
∞
∫
s s
resonance
Perturbation theory (1-loop)
Hammer & R-M
All orders
Dispersion theory
• S-quarks are not inert
• Non-perturbative effects dominate (LEC’s)
rs,M2 =
6π
dtImGM
s (t)t2
4mK2
∞
∫
• 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 cancellationsExperiment & lattice will give an answer
CombiningPT, dispersion theory, & lattice QCD
€
GM(s)(Q2 = 0.1) = 0.37 ± 0.20 ± 0.26 ± 0.07
€
s = GM(s)(Q2 = 0.1) − 0.13bs
r
€
=0.37 ± 0.20 ± 0.26 ± 0.15
RA
“Reasonable range”: lattice & disp rel
SAMPLE
Radiative Corrections & the Hadronic Weak Interaction
• GAe
• N !
• PV photo- and electro-production (threshold)
• Vector analyzing power ()
at Q2=0.1 (GeV/c)2
( ) 39.045.022.01
31.029.014.0
±±==
±±=
TG
GeA
sM
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
e
r e p
p
+⋅⋅⋅γ
“Anapole” effects : Hadronic Weak Interaction
γ
ZZ
γ+
Nucleon Green’s Fn : Analogous effects in neutron -decay, PC electron scattering…
“Anapole” Effects
€
€
+
€
p
€
+L
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 GeA
Nuclear PV Effects
€
PV NN interaction
Carlson, Paris, Schiavilla Liu, Prezeau, Ramsey-Musolf
Suppressed by ~ 1000
at Q2=0.1 (GeV/c)2
125 MeV:no backgroundsimilar sensitivity to GA
e(T=1)
SAMPLE Results R. Hasty et al., Science 290, 2117 (2000).
200 MeV update 2003:Improved EM radiative corr.Improved acceptance modelCorrection for background
• s-quarks contribute less than 5% (1) to the proton’s magnetic moment.
200 MeV dataMar 2003
D2
H2
Zhu
, et
al.
E. Beise, U MarylandRadiative corrections
Transition Axial Form Factor
€
GANΔ (0) =
2
3
gπNΔFπ
mN
1− Δπ( )
€
GANΔ,e (0) = GA
NΔ (0) 1+ RAΔ
( )
Off Diagonal Goldberger-Treiman Relation Zhu, R-M
O(p2) chiral corrections ~ few %N!N ~ 5%
Rad corrections, “anapole” ~ 25%Study GA
N(Q2)/ GAN(0)
Measuring GAN(Q2)
GAN & “d”””
Axial response , GAN only
ALR ~ Q2 (1-2sin2W) Zhu, Maekawa, Sacco, Holstein, R-M
Nonzero ALR(Q2= 0)
Weak interactions of s-quarks are puzzling
Hyperon weak decays
€
Σ+ → nπ + Σ+ → pπ 0 Σ− → nπ −
Λ → pπ − Λ → nπ 0 Ξ− → Λπ 0 Ξ0 → Λπ 0
€
MB → ′ B π = U B A + Bγ 5[ ]UB
S-Wave: Parity-violating
P-Wave: Parity-conserving
symmetry not sufficient
Weak interactions of s-quarks are puzzling
€
rΣ+ → pγ ,
r Λ → nγ ,K
€
MB → ′ B λ = −i
MB + M ′ B
U σ μν A + Bγ 5( )U F μν
M1 (PC)
E1 (PV)
€
αB ′ B =2Re A B*
A2
+ B2
€
αB ′ B ~ ms Λχ ~ 0.15
€
αΣ+ p
~ − 0.76 ± 0.08
αΞ 0Σ0 ~ − 0.63± 0.09
Th’y
Exp’t
Weak interactions of s-quarks are puzzlingResonance saturation
€
B
€
′B
€
′′B
€
€
B
€
′B
€
′′B
€
€
+Holstein & Borasoy
S11
Roper
S-Wave
P-Wave
€
12
+ 12
− 12
+
12
+ 12
+ 12
+
€
12
+ 12
− 12
+
12
+ 12
+ 12
+
Fit matrix elements
Weak interactions of s-quarks are puzzlingResonance saturation
€
B
€
′B
€
′′B
€
€
B
€
′B
€
′′B
€
€
+Holstein & Borasoy
S11
Roper
S-Wave
P-Wave
€
12
+ 12
− 12
+
12
+ 12
+ 12
+
€
12
+ 12
− 12
+
12
+ 12
+ 12
+
Fit matrix elements
€
B
€
′B
€
′′B
€
€
B
€
′B
€
′′B
€
€
+
€
B( ) = −π ′ ′ B ( ) = π ′ B ( ) S/P wave fit Close gap with αBB’
Weak interactions of s-quarks are puzzling
€
WB ′ ′ B ~ Λχ gπ
€
WB ′ ′ B ~ 5 Λχ gπ
Natural
Fit
€
~GF Fπ
2
2 2~ 3.8 ×10−8
Is deviation from QCD-based expectations due to presence of s-quarks or more fundamental dynamics?
We have a S=0 probe
€
N
€
€
Use PV to filter out EM transition
Zhu, Maekawa, Holstein, MR-M
€
L = ie
Λχ
dΔ Δ μ+ γ λ pF μλ + h.c.PV, E1
Amplitude
€
Aγ = 0
€
Aγ = 2dΔ
C3V
mN
Λχ
+LPV Asymmetry
Large NC , spin-flavor SU(4) Finite NC
Low energy constant
We have a S=0 probe
€
N
€
€
€
L = ie
Λχ
dΔ Δ μ+ γ λ pF μλ + h.c.
Naïve dimensional analysis (NDA)
Resonance saturation
€
N
€
€
12
−
€
€
N
€
€
32
−
€
€
+
€
HWΔS= 0
€
Aγ ~ 5 ×10−8
d~ g
€
Aγ ~ 1×10−6 d~ 25g
Measuring d
d = 100 genhanced HW
S=0
d = 0 , GAN only
ALR ~ Q2 (1-2sin2W) Zhu, Maekawa, Sacco, Holstein, R-M
N! Transition
Measure Q2-dependence of ALR to learn
• d
• GANQ2)/ GA
N0)
• RA
• MINERVA: GAN(0) ?
Vector Analyzing Power
€
An ~r S ⋅
r K × ′
r K
• T-odd, P-even correlation
• Doubly virtual compton scattering (VVCS):new probe of nucleon structure
• Implications for radiative corrections in other processes: GE
p/GMp, -decay…
• SAMPLE, Mainz, JLab experiments
What specifically could we learn?
Vud
Vector Analyzing Power
γ€
V
€
V
γ+
V=: VVCS
Re M(M
boxMcross) Rosenbluth
Im MM
box VAP
V=W,Z: Electroweak VVCS
Re MV(MV
boxMVcross) -decay, RA,…
Im MVMV
box -decay T-violation
Direct probe
Vector Analyzing Power
Mott: MN!1
SAMPLE
EFT to O(p2)
Diaconescu, R-M
I=1, r2
O(p0)
O(p4)
1460
Vector Analyzing Power
Constrained by SAMPLE
300
Dynamical ’s?
Radiative Corrections & the Hadronic Weak Interaction
• GAe
• N !
• PV photo- and electro-production (threshold)
• Vector analyzing power ()
Theory for RA good to ~ 25%
Further test of RAd & HW
EFT for low energy good to ~ 25%; more tests!
New window on electroweak VVCS: -decay, sin2W,…
Weak Mixing Angle: Scale Dependence
sin2W
(GeV)
SLAC E158 (ee) JLab Q-Weak (ep)
e+e- LEP, SLD
Atomic PV N deep inelastic
Czarnecki, Marciano Erler, Kurylov, MR-M
Comparing Qwe and QW
p
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture. -> e+e
SUSY dark matter
is Majorana
RPV 95% CL fit to weak decays, MW, etc.
Kurylov, Su, MR-M
€
QWe,SUSY QW
e,SM
€
QWp,SUSY QW
p,SM
SUSY loops
Comparing Qwe and QW
p
Erler, Kurylov, R-M
QWP = 0.0716 QW
e = 0.0449
Experiment
SUSY Loops
E6 Z/ boson
RPV SUSY
Leptoquarks
SM SM
€
±0.0029
€
±0.0040
sin2W
(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 Qwe and QW
p
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
SUSY dark matter
Kurylov, R-M, Su
SUSY loops
RPV 95% CL€
QWp,SUSY QW
p,SM
€
QWe,SUSY QW
e,SM
E158 &Q-Weak
JLab Moller
Linear collider
Comparing AdDIS and Qw
p,e
e
p
RPV
Loops
SUSY effects
Comparing Qwe and QW
p
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
SUSY dark matter
Kurylov, R-M, Su
SUSY loops
RPV 95% CL€
QWp,SUSY QW
p,SM
€
QWe,SUSY QW
e,SM
E158 &Q-Weak
JLab Moller
Linear collider
“DIS Parity”
Higher Twist “Pollution”
E=11 GeV =12.50
Different PDF fits
Sacco, R-M preliminary
~0.4%
€
ALR Q2
€
y
Higher Twist “Pollution”
Castorina & Mulders
Sacco & R-M preliminary
Open issues
• QCD evolution
• Double handbag
• Moment inversion
€
FLD, HT
€
F2D, HT
Tasks for the “modern era” & futureStrange 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-violationas suggested by NuTeV?
• Theory: how big is twist pollution?
• Theory: relating n(r) & APV
Hardronic PV • Lots of new exp’t & theory….