parity-violation and strange quarks: theoretical perspectives
DESCRIPTION
Parity-Violation and Strange Quarks: Theoretical Perspectives. M.J. Ramsey-Musolf. Hall A Collaboration Meeting: December ‘05. Outline. Historical Context Strange quarks: what havewe learned? Other aspects of parity-violationand QCD: radiative corr,N to D , gg. - PowerPoint PPT PresentationTRANSCRIPT
Parity-Violation and Strange Quarks: Theoretical Perspectives
M.J. Ramsey-Musolf
Hall A Collaboration Meeting: December ‘05
Outline
• Historical Context
• Strange quarks: what havewe learned?
• Other aspects of parity-violationand QCD: radiative corr,N to ,
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
• What is the internal landscape of the nucleon?
• What does QCD predict for the properties of nuclear matter?
• Where is the glue that binds quarks into strongly-interactingparticles and what are its properties?
Tribble Report
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
MAINZ
G0
K. Aniol et al, nucl-ex/0506011
Strange Quarks in the Nucleon: What have we learned?
• Strange quarks don’t appear in the conventional Quark Model picture of the nucleon
• Perturbation theory is limited
QCD / ms ~ 1 No HQET
mK / ~ 1/2 PT ?
• Symmetry is impotent
Js = JB - 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
What PT can (cannot) say
Strange magnetismIto & R-M; Hemmert, Meissner, Kubis; Hammer, Zhu, Puglia, R-M
The SU(3) chiral expansion for B :
O (p2)
mq -independent
What PT can (cannot) say
Strange magnetismIto & R-M; Hemmert, Meissner, Kubis; Hammer, Zhu, Puglia, R-M
The SU(3) chiral expansion for B :
O (p3)
non-analytic in mq
unique to loops leading SU(3)
What PT can (cannot) say
Strange magnetismIto & R-M; Hemmert, Meissner, Kubis; Hammer, Zhu, Puglia, R-M
The SU(3) chiral expansion for B :
O (p4)
non-analytic in mq (logs)
What PT can (cannot) say
Strange magnetismIto & R-M; Hemmert, Meissner, Kubis; Hammer, Zhu, Puglia, R-M
The SU(3) chiral expansion for B :
SU(3) Sym breaking
O (p4)
Two-deriv operators
+ 1/mN terms
M = diag (0,0,1)
What PT can (cannot) say
Strange magnetismIto & R-M; Hemmert, Meissner, Kubis; Hammer, Zhu, Puglia, R-M
The SU(3) chiral expansion for B :
O (p2) O (p3) O (p4)• converges as (mK / )n
• good description of SU(3) SB
What PT can (cannot) say
Strange magnetismIto & R-M; Hemmert, Meissner, Kubis; Hammer, Zhu, Puglia, R-M
Implications fors :
O (p2) singlet
O (p3,p4) loop only
O (p2,p4) octet
• Near cancellation of O (p2,p4) octet & loop terms• Exp’t: b0 + 0.6 b8 terms slightly > 0• Models: different assumptions for b0 + 0.6 b8 terms
O (p4) octet only
O (p4) singlet
Q2 -dependenceof Gs
M
G0 projected
Dispersion theory
Chiral perturbation theory “reasonable range” for slope
SAMPLE 2003
Happex projected
Lattice QCD theory
What PT can (cannot) say
Strange magnetism
GMs (qs) = μs + 1
6 q2 rs,M2 +L
O (p4), unknown LEC
O (p3), parameter free O (p4) , cancellation
O (p4), octet
What PT can (cannot) say
Strange magnetism
GMs (qs) = μs + 1
6 q2 rs,M2 +L
O (p3,p4), loops O (p4), octet
O (p4), unknown LEC
What PT can (cannot) say
Strange electricityIto & R-M; Hemmert, Meissner, Kubis; Hammer, Zhu, Puglia, R-M
The SU(3) chiral expansion for s :
O (p3): non-analytic in mq (loops) + mq -independent cts
What PT can (cannot) say
Strange electricityIto & R-M; Hemmert, Meissner, Kubis; Hammer, Zhu, Puglia, R-M
The SU(3) chiral expansion for s :
O (p3), octet
O (p3), unknown LEC
O (p3), loops
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
€
€
K +s s
Loops “vs” poles
No dichotomy: kaon cloud is resonant
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
€
€
K +s s
Kaon cloud
Not sufficient to explain Gs
E,M
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
€
€
K +
Kaon cloud models
Not reliable guide to sign or magnitude of Gs
E,M
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
€
€
K +
Chiral models
Implicit assumptions about b0 , c0 , b0
r , …
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
€
€
K +
Disconnected Insertions
~ +…
Still a challenge
s s
Dispersion theoryJaffe Hammer, Drechsel, R-M
€
Ms = −
4mN2
πdt
ImGMs (t)
t 29mπ
2
∞
∫
Strong interaction scattering amplitudese+ e- K+ K-, etc.
Contributing States
Dispersion theoryJaffe Hammer, Drechsel, R-M
€
Ms = −
4mN2
πdt
ImGMs (t)
t 29mπ
2
∞
∫
Strong interaction scattering amplitudese+ e- K+ K-, etc.
Dispersion theoryJaffe Hammer, Drechsel, R-M
€
Ms = −
4mN2
πdt
ImGMs (t)
t 29mπ
2
∞
∫
Strong interaction scattering amplitudese+ e- K+ K-, etc.
Hammer & R-MDispersion theory
€
Ms = −
4mN2
πdt
ImGMs (t)
t 29mπ
2
∞
∫All orders
€
€
K +
• Naïve pert th’y O (g2)• Kaon cloud models• Unitarity violating
Unitarity
Hammer & R-MDispersion theory
€
Ms = −
4mN2
πdt
ImGMs (t)
t 29mπ
2
∞
∫All orders
Unitarity
s s res
• S-quarks are not inert
• Non-perturbative effects dominate (LEC’s)
• Kaon cloud is resonant
Hammer & R-MDispersion theory
€
Ms = −
4mN2
πdt
ImGMs (t)
t 29mπ
2
∞
∫
• Kaon cloud not dominant
• Not sufficient data to includeother states
Kaon cloud
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 ComputationsLeinweber et al
Disconn s/d
Charge Sym
B exp’t
Lattice Computations
€
s = Fμ p
u
μ Σu , μ s
μ dloop( )
€
s ≈ −0.05 ± 0.02
Leinweber et al
€
s μdloop
dloop: Lattice
s: kaon loops
Charge Symmetry
s/d loop ratio
• Charge symmetry• Measured octet m.m.’s• Lattice d
loop
• Kaon loops
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
€
€
K +
Disconnected Insertions
~ +…
Still a challenge
s s
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
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
€
€
K +
Chiral models
Implicit assumptions about b0 , c0 , b0
r , …
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
Jido & Weise
Implicit assumptions about b0 , c0 , b0
r , …
No
b0,8=0
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
Implicit assumptions about b0 , c0 , b0
r , … s > 0
Jido & Weise
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
Implicit assumptions about b0 , c0 , b0
r , …
Zou & Riska (QM)
€
€
K +Give wrong sign ???
~ s in g.s. s in excited state (p wave)
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
Implicit assumptions about b0 , c0 , b0
r , …€
(1405)
€
K +Give right sign ???~ s in g.s., (s wave) s in excited state
Zou & Riska (QM)
s > 0
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
Implicit assumptions about b0 , c0 , b0
r , …
Zou & Riska (QM)
s s
s < 0
t-channel resonances?
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
Implicit assumptions about b0 , c0 , b0
r , …
Chiral Quark Soliton
s > 0
Implicit kaon cloud + b3-7…
€
qqq bag
€
K +s s
resonances ?
Strange Quarks in the Nucleon: What have we learned?
• Dispersion Theory
• Models
• Lattice QCD
Js = JB - 2 JEM, I=0 Unknown constants
It’s all in the low energy constants
Implicit assumptions about b0 , c0 , b0
r , …
Chiral Quark Soliton
s < 0
Implicit kaon cloud + b3-7…
€
qqq bag
€
K +s s
resonances ?
Strange Quarks in the Nucleon: What have we learned?
Js = JB - 2 JEM, I=0 Unknown constants
New puzzles: higher Q2-dependence
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
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,…
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?
Conclusions• Measurements of neutral weak form factors
have challenged QCD theory:
• PV program has stimulated a variety of other developments at the interface of QCD and weak interactions:
• Powerful new probes of SM & beyond: Qwe,p , DIS
• Kaon cloud is resonant, but not dominant• Loop calculations are unreliable guide• Symmetry limited by presence of unknown constants
• Models remain interesting, but ad hoc (implicit LECs)• Lattice challenged to obtain disconn insertions
• Axial radiative corrections consistent with experiment• Axial N to new QCD testing ground: GA
N, d• Electroweak box graphs: new insights from ?