Transcript Parity-Violation with Electrons: Theoretical Perspectives

Parity-Violation with Electrons:
Theoretical Perspectives
M.J. Ramsey-Musolf
PV: Past, Present, & Future
Prehistory
1970’s
SLAC DIS
Atomic PV
Standard Model
sin2qW ~ 10%
1980’s
Mainz 8Be
MIT 12C
PV eq couplings
~ 10%
PV: Past, Present, & Future
Modern Era
1990’s
MIT
JLab
Mainz
APV
GsE,M ~ few %
GA & rad corrections
rn(r)
sin2qW ~ 1%
Anapole moment
2000’s
SLAC Moller
JLab QWeak
APV
Standard Model & beyond
sin2qW < 1%
Anapole moment
JLab
Mainz
GAND
HWI (DS=0): dD , Ag
VVCS: An
PV: Past, Present, & Future
Future
2010’s
JLab DIS-Parity
Moller (2)
Standard Model & beyond
sin2qW < 1%
2020’s
NLC
sin2qW < 0.1%
Moller (3)
Quarks, Gluons, & the Light Elements
How does QCD make hadronic matter?
PV &
strange
quarks
2.5
2.0
Hybrids
qq Mesons
GPD’s: “Wigner
Distributions” (X. Ji)
mq-dependence of
nuclear properties
exotic
nonets
1.5
Pentaquark, Q+
1.0
L = 01 2 3 4Gluonic effects
Lattice QCD
Strange Quarks in the Nucleon:
What have we learned?
Effects in N s g  s N are much less
pronounced than in N s s N , N s g g 5s N


OZI violation
gNN
gNN
1

2

Jaffe ‘89
Hammer, Meissner,
Drechsel ‘95
• Dispersion Relations
• Narrow Resonances
• High Q2 ansatz
Strange Quarks in the Nucleon:
What have we learned?
Effects in N s g  s N are much less
pronounced than in N s s N , N s g g 5s N



HAPPEX
SAMPLE
Strange Quarks in the Nucleon:
What have we learned?
Theory: how
do we understand
of
Challenge
to understand
QCD atdynamics
deep,
small sslevel
effects in vector current channel ?
detailed
• 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
cPT ?
• Symmetry is impotent
Js = JB + 2 JEM, I=0
Unknown
constants
Happex projected
SAMPLE
2003
Q2 -dependence
of GsM
G0 projected
Lattice QCD theory
Dispersion theory
Chiral perturbation theory
“reasonable range” for slope
Lattice Computations
Dong, Liu, & Williams (1998)
See also
Leinweber et al
Lewis, Wilcox, Woloshyn (2003)
• Quenched QCD
• Quenched QCD
• Wilson fermions
• Wilson fermions
• 100 gauge configurations
• 2000 gauge configurations
• 300-noise estimate/config
• 60-noise estimate/config
Lattice Computations
Leinweber et al
s  F
, 
 up
s
 u
 dloop
Lattice calculation
• Charge symmetry
• Measured octet m.m.’s
• Chiral symmetry
• Unquenching
s  0.05 0.02
What cPT can (cannot) say
Strange magnetism as an illustration
G (q )  s +
s
M
s
Ito, R-M
Hemmert,
Meissner, Kubis
Hammer, Zhu, Puglia, R-M
1 2 2
6
s, M
qr
+
s  2MN  c bs +
Unknown lowenergy constant
(incalculable)
Kaon loop contributions
(calculable)
What cPT can (cannot) say
Strange magnetism as an illustration
G (q )  s +
s
M
2
s,M
r
s
6

c
{
 2M  r
N

 bs
 c 
1 2 2
6
s, M
qr
+
NLO, unknown LEC

1
mK 
2
2   MN
+
+ (5D  6DF + 9F )
+ 7ln
18
 mK

LO, parameter free
}
NLO, cancellation
Dispersion theory
Slope of
GMs
2
s, M
r
6



s
M
2
Im G (t)
2 dt t
9m

Strong interaction scattering amplitudes
e+ e-
K+ K-, etc.
Jaffe
Hammer, Drechsel, R-M
Dispersion theory
6
r 

2
s, M
Hammer & R-M

s
M
2
ImG (t)
 2 dt t
4m
K
All orders
K+



Perturbation theory (1-loop)
Dispersion theory
• S-quarks are not inert
• Non-perturbative effects
dominate (LEC’s)
6
r 

2
s, M
Hammer & R-M

s
M
2
ImG (t)
 2 dt t
4m
K
All orders
 resonance
s s
Perturbation theory (1-loop)
Dispersion theory
6
r 

2
s, M

s
M
2
ImG (t)
 2 dt t
4m
K
Can’t do the whole integral
• Are there higher mass
excitations of s s pairs?
• Do they enhance or cancel
low-lying excitations?
Experiment
Models & exp’t
& lattice will
give
suggest
an answer
cancellations
?
Combining cPT, dispersion
theory, & lattice QCD
SAMPLE
G (Q  0.1)  0.37  0.20  0.26  0.07
(s)
M
2
dRA

s  GM(s) (Q2  0.1)  0.13bsr
 0.37  0.20  0.26  0.15

“Reasonable range”:
lattice & disp rel
Radiative Corrections & the
Hadronic Weak Interaction
• G Ae
• N !D
• PV  photo- and electro-production
(threshold)
• Vector analyzing power (gg)
at Q2=0.1 (GeV/c)2
GMs  0.14  0.29  0.31
GAe T  1  0.22  0.45  0.39
• s-quarks contribute less
than 5% (1s) to the proton’s
magnetic form factor.
• proton’s axial structure is
complicated!
Models for s
Radiative corrections
R. Hasty et al., Science 290, 2117 (2000).
Axial Radiative Corrections
e
“Anapole” effects : Hadronic
Weak Interaction
p
g
+ 
e
p
Z
g
+
Z
g
Nucleon Green’s Fn :
Analogous effects in
neutron -decay, PC
electron scattering…
“Anapole” Effects
+
Hadronic PV
g
+

p


Zhu, Puglia, Holstein, R-M (cPT)
Maekawa & van Kolck (cPT)
Riska (Model)
Can’t account for a large reduction in GeA
Zhu et al.
Nuclear PV Effects
g

PV NN
interaction
Carlson, Paris, Schiavilla
Liu, Prezeau, Ramsey-Musolf
Suppressed
by ~ 1000
R. Hasty et al., Science 290, 2117 (2000).
SAMPLE Results
at Q2=0.1 (GeV/c)2
D2
200 MeV data
Mar 2003
Zhu, et al.
H2
• 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  background
125 MeV:
no  background
similar sensitivity
to GAe(T=1)
Radiative corrections
E. Beise, U Maryland

Transition Axial Form Factor
Off Diagonal Goldberger-Treiman Relation
2 gND F
G (0) 
1 D  
3 mN
ND
A
N!N ~ 5%
ND,e
A
G
Study GA
(0)  G (0)1+ R
ND(Q2)/
ND
A
GA
ND(0)
D
A
Zhu, R-M
O(p2) chiral
corrections ~
few %

Rad corrections,
“anapole” ~ 25%
Measuring GAND(Q2)
Nonzero
ALR(Q2= 0)
Axial response , GAND only
GAND & “dD”,
ALR ~ Q2 (1-2sin2qW)
Zhu, Maekawa, Sacco,
Holstein, R-M
Weak interactions of s-quarks are puzzling
Hyperon weak decays

+  n +
+  p 0
  n 
  p 
  n 0
   0 0   0
M B B   UB A + Bg 5 UB
S-Wave:
Parity-violating
c symmetry
not sufficient
P-Wave:
Parityconserving
Weak interactions of s-quarks are puzzling
+  pg ,   ng ,
E1 (PV)
i
MB B   
U s  A + B g 5 U F 
MB + MB 
M1 (PC)
 BB  
2Re A B
A +B
2

*
2
 BB  ~ ms  c ~ 0.15

+
p
~  0.76  0.08
  ~  0.63  0.09
0 0
Th’y
Exp’t
Weak interactions of s-quarks are puzzling
Resonance saturation

Holstein & Borasoy
S-Wave

P-Wave

B
B
1+
2
1
2
1+
2
1 +
2
B
1+
2
1 +
2
Fit matrix
elements



+
B
1+
2
1+

2

B
B
1
2
1+
2
S11
1+
2
1+
2
Roper
Weak interactions of s-quarks are puzzling
Resonance saturation

Holstein & Borasoy
S-Wave

P-Wave

B
B
1+
2
1
2
1+
2
Fit matrix
elements


B
1 +
2
B
1+
2
B
1+

2

B
B
1
2
1+
2
S11
1+
2
1+
2
Roper
g
g
B
+
1+
2
1 +
2
+

B

B
B
 B 
  B    B  S/P wave fit





B
Close gap
with BB’
Weak interactions of s-quarks are puzzling
Natural
W BB  ~  c g
Fit
W BB  ~ 5  c g
GF F2
~
~ 3.8 108
2 2



Is deviation from QCD-based expectations
due to presence of s-quarks or more
fundamental dynamics?
We have a DS=0 probe
g
Use PV to
filter out EM
transition
N

PV, E1
Amplitude
Ag  0

D

Zhu, Maekawa,
Holstein, MR-M
Low energy
constant
e
L  i
dD D+ g  p F  + h.c.
c
PV Asymmetry

Large NC , spin-flavor SU(4)
dD mN
Ag  2 V
+
C3  c
Finite NC
We have a DS=0 probe
g
N

e
+

L  i
dD D  g  p F + h.c.
c
D

Naïve dimensional
analysis (NDA)
dD ~ g
H

Resonance saturation
DS 0
W
g
1
2
N
8
Ag ~ 5 10





dD ~ 25g

D

+

g
3
2
N

D
6
Ag ~ 110
Measuring dD
dD = 0 , GAND only
dD = 100 g ,
enhanced HWDS=0
ALR ~ Q2 (1-2sin2qW)
Zhu, Maekawa, Sacco,
Holstein, R-M
N!D Transition
Measure Q2-dependence
of ALR to learn
• dD
• GANDQ2)/ GAND0)
• RAD
• MINERVA: GAND(0) ?
Vector Analyzing Power
An ~ S  K  K 
• T-odd, P-even correlation

What specifically
could we learn?
• Doubly virtual compton scattering (VVCS):
new probe of nucleon structure
• Implications for radiative corrections in
other processes: GEp/GMp, -decay…
• SAMPLE, Mainz, JLab experiments
Vud
Vector Analyzing Power
V

g
+
V
g

V=g: VVCS
Direct
probe
Re Mg*(Mggbox+Mggcross)
Im Mg*Mggbox
Rosenbluth
VAP
V=W,Z: Electroweak VVCS
Re MV*(MVgbox+MVgcross) -decay, RA,…
Im MV*MVgbox
-decay T-violation
Vector Analyzing Power
q1460
SAMPLE
Mott: MN!1
O(p0)
EFT to O(p2)
kI=1, r2
Diaconescu,
R-M
O(p4)
Vector Analyzing Power
q300
Dynamical ’s?
Constrained
by SAMPLE
Radiative Corrections & the
Hadronic Weak Interaction
• G Ae
Theory for RA good to ~ 25%
• N !D
Further test of RAD ; dD & HWqq
• PV  photo- and electro-production
(threshold)
• Vector analyzing power (gg)
EFT for low energy good
to ~ 25%; more tests!
New window on electroweak
VVCS: -decay, sin2qW,…
Weak Mixing Angle: Scale Dependence
Czarnecki, Marciano
Erler, Kurylov, MR-M
Atomic PV
N deep inelastic
sin2qW
e+e- LEP, SLD
SLAC E158 (ee)
JLab Q-Weak (ep)
 (GeV)
Comparing Qwe and QWp
SUSY loops
 SUSY
dark matter
dQ
p,SUSY
W
c ->
e e
 is Majorana
p,SM
QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
W
+
Q
RPV 95% CL fit to
weak decays, MW, etc.
dQWe, SUSY QWe, SM
Kurylov, Su, MR-M
Comparing Qwe and QWp
QWP = 0.0716
 0.0029
QWe = 0.0449
 0.0040
Experiment
SUSY Loops

E6 Z/ boson

RPV SUSY
Leptoquarks
SM
SM
Erler, Kurylov, R-M
Additional PV electron scattering ideas
Czarnecki, Marciano
Erler et al.
Atomic PV
N deep inelastic
DIS-Parity, JLab
Linear
Collider e-e-
DIS-Parity, SLAC
sin2qW
e+e- LEP, SLD
SLAC E158 (ee)
Moller, JLab
JLab Q-Weak (ep)
 (GeV)
Comparing Qwe and QWp
Kurylov, R-M, Su
SUSY loops
 SUSY
dark matter
dQWp,SUSYQuickTime™
QWp,SM and a TIFF (Uncompressed) decompressor are needed to see this picture.
Linear
collider
E158 &QWeak
JLab Moller
RPV 95% CL
dQWe, SUSY QWe, SM
Comparing AdDIS and Qwp,e
e
RPV
Loops
p
SUSY effects
Comparing Qwe and QWp
“DIS Parity”
Kurylov, R-M, Su
SUSY loops
 SUSY
dark matter
dQWp,SUSYQuickTime™
QWp,SM and a TIFF (Uncompressed) decompressor are needed to see this picture.
Linear
collider
E158 &QWeak
JLab Moller
RPV 95% CL
dQWe, SUSY QWe, SM
Higher Twist “Pollution”
~0.4%
Different
PDF fits
ALR Q2
y

E=11 GeV
q=12.50
Sacco, R-M
preliminary
Higher Twist “Pollution”
Sacco & R-M
preliminary
FLD, HT
Castorina &
Mulders
Open issues
F2D, HT
• 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!D, VAP
• Theory: quark mass (m) dependence
• Measure dD
SM & new
physics
• DIS-Parity: Is there significant I-violation
as suggested by NuTeV?
• Theory: how big is twist pollution?
• Theory: relating rn(r) & APV
Hardronic PV
• Lots of new exp’t & theory….