Precision Electroweak Physics and QCD at an EIC M.J. Ramsey-Musolf Wisconsin-Madison NPAC...
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Precision Electroweak Physics and QCD at an EIC
M.J. Ramsey-MusolfWisconsin-MadisonQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
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http://www.physics.wisc.edu/groups/particle-theory/
NPACTheoretical Nuclear, Particle, Astrophysics & Cosmology
LBL, December 2008
Questions
• What are the opportunities for probing the “new Standard Model” and novel aspects of nucleon structure with electroweak processes at an EIC?
• What EIC measurements are likely to be relevant after a decade of LHC operations and after completion of the Jefferson Lab electroweak program?
• How might a prospective EIC electroweak program complement or shed light on other key studies of neutrino properties and fundamental symmetries in nuclear physics?
Outline
• Lepton flavor violation: e-+A K - + A
• Neutral Current Processes: PV DIS & PV Moller
• Charged Current Processes: e-+A K ET + j
Disclaimer: some ideas worked out in detail; others need more research
Lepton Number & Flavor Violation
• LNV & Neutrino Mass
• Mechanism Problem
• CLFV as a Probe
• K e Conversion at EIC ?
Uncovering the flavor structure of the new SM and its relationship with the origin of neutrino mass is an important task. The observation of charged lepton flavor violation would be a major discovery in its own right.
-Decay: LNV? Mass Term?
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e−
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e−
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M
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W −
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W −
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A Z,N( )
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A Z − 2,N + 2( )0.1
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100
1000
Effective
( )Mass meV
12 3 4 5 6 7
12 3 4 5 6 7
12 3 4 5 6 7
1 ( )Minimum Neutrino Mass meV
U1e=.866δm2
sol=7meV
2
U2e=.5δm2
atm=2meV
2
U 3e =
Inverted
Normal
Degenerate
Dirac Majorana
-decayLong baseline
?
?
Theory Challenge: matrix elements+ mechanism
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mν
EFF= Uek
2mk e2iδ
k
∑
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e−
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e−
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χ 0
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˜ e −
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u
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d
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e−
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e−
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M
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W −
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W −
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u
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u
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d
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d
mEFF & neutrino spectrum
Normal Inverted
-Decay: Mechanism
Dirac Majorana
Theory Challenge: matrix elements+ mechanism
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mν
EFF= Uek
2mk e2iδ
k
∑
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e−
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e−
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χ 0
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˜ e −
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u
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M
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W −
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u
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Mechanism: does light M exchange dominate ?
How to calc effects reliably ? How to disentangle H & L ?
O(1) for ~ TeV
-Decay: Interpretation
0.1
1
10
100
1000
Effective
( )Mass meV
12 3 4 5 6 7
12 3 4 5 6 7
12 3 4 5 6 7
1 ( )Minimum Neutrino Mass meV
U1e=.866δm2
sol=7meV
2
U2e=.5δm2
atm=2meV
2
U 3e =
Inverted
Normal
Degeneratesignal equivalent to degenerate hierarchy
Loop contribution to m of inverted hierarchy scale
Sorting out the mechanism
• Models w/ Majorana masses (LNV) typically also contain CLFV interactions
RPV SUSY, LRSM, GUTs (w/ LQ’s)
• If the LNV process of arises from TeV scale particle exchange, one expects signatures in CLFV processes
• K e Conversion at EIC could be one probe
CLFV, LNV & the Scale of New Physics
Present universe Early universe
Weak scale Planck scale
log10(μ / μ0)
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αS−1
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αL−1
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αY−1
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μ
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e
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γ
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μ
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e
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A Z,N( )
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A Z,N( )
MEG: μγ ~ 5 x 10-14
μ2e: Bμ->e ~ 5 x 10-17
??
R = Bμ->e
Bμ->eγ
Also PRIME
μ!eγ: M1
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μ!e: M1 ! R ~ α
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Lepton Flavor & Number Violation
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μ
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e
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γ
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μ
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A Z,N( )
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A Z,N( )
MEG: Bμ->eγ ~ 5 x 10-14
μ2e: Bμ->e ~ 5 x 10-17
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μ
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e
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γ*
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e+
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e+
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Δ−−
Logarithmic enhancements of R
Raidal, Santamaria; Cirigliano, Kurylov, R-M, Vogel
0decay
RPV SUSY
LRSM
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Low scale LFV: R ~ O(1) GUT scale LFV: R ~ Oα
Lepton Flavor & Number Violation
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e
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γ
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A Z,N( )
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X
Exp: B->eγ ~ 1.1 x 10-7
EIC: ~ 103 | A1e|2 fb
Raidal, Santamaria; Cirigliano, Kurylov, R-M, Vogel
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γ*
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˜ ν
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γ*
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Δ−−
Logarithmic enhancements of R
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|A2e|2 < 10-8
EIC: ~ 10-5 fb
If |A2e|2 ~ |A1
e|2
Log or tree-level enhancement:
|A1e|2 / |A2
e|2 ~ | ln me / 1 TeV |2 ~ 100
BKeγ48 3α|A2e|2
Need ~ 1000 fb
M1 operator
Penguin op
CLFV & Other Probes
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γ
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A Z,N( )
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Exp: B->eγ ~ 1.1 x 10-7
EIC: ~ 103 | A1e|2 fb
hμe hee
+ hμμ hμe
+ hμ he
if RH; PV Moller if LH
Ke(γ
Doubly Charged Scalars
μKe(γ hee he
+ heμ hμ
+ he h
All hab $ m if part of see-saw
LHC: ΔΔBRs (in pair prod)
LFV with leptons: HERA
Veelken (H1, Zeus) (2007)
Leptoquark Exchange: Like RPV SUSY /w /
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eqq eff op
lq|2 < 10-4 (MLQ / 100 GeV)2
HW Assignment:
• Induce Keγat one loop?
• Consistent with BKeγ? HERA limits look stronger
• Connection w/ m & in GUTS ?
• Applicable to other models that generate tree-level ops?
LFV with leptons: recent theory
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Kanemura et al (2005)
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μqq eff opSUSY Higgs Exchange
lq|2 < 2 x 10-2 (MLQ / 100 GeV)2
lq|2 < 10-4 (MLQ / 100 GeV)2 HERA
Neutral Current Probes: PV
• Basics of PV electron scattering
• Standard Model: What we know
• New physics ? SUSY as illustration
• Probing QCD
PV Electron Scattering
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re −€
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e−, p€
e−, p
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Z 0
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e−
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e−, p€
e−, p
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γ
Parity-Violating electron scattering
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APV =N↑↑ − N↑↓
N↑↑ + N↑↓
=GFQ2
4 2παQW + F(Q2,θ)[ ]
“Weak Charge” ~ 0.1 in SM
Enhanced transparency to new physics
Small QCD uncertainties (Marciano & Sirlin; Erler & R-M)
QCD effects (s-quarks): measured (MIT-Bates, Mainz, JLab)
Effective PV e-q interaction & QW
Low energy effective PV eq interaction
Weak Charge:
Nu C1u + Nd C1d
Proton:
QWP = 2 C1u + C1d = 1-4 sin2W ~ 0.1
Electron:
QWe = C1e = -1+4 sin2W ~ - 0.1
QW and Radiative Corrections
Tree Level
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QWf = gV
f gAe
Radiative Corrections
QWf =ρPV (2I3
f −4QfκPV )+λ fsin2 θW
Flavor-independent
Normalization Scale-dependent effective weak mixing
Flavor-dependent
Constrained by Z-pole precision observables
Large logs in
Sum to all orders with running sin2W & RGE
Weak Mixing in the Standard Model
Scale-dependence of Weak Mixing
JLab Future
SLAC Moller
Parity-violating electron scattering
Z0 pole tension
PVES & New Physics
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Z 0
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˜ χ −
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˜ χ 0
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˜ e −
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f€
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Z 0
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˜ e −
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e−
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˜ q Lj
1j1
1j1
Radiative Corrections
RPV
SUSY Z/ Bosons Leptoquarks
Doubly Charged Scalars
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′Z
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LQ
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Semi-leptonic only
Moller only
PVES & APV Probes of SUSY
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δQ
WP
, S
US
Y /
QW
P,
SM
RPV: No SUSY DM Majorana s
SUSY Loops
δQWe, SUSY / QW
e, SM
gμ-2
12 GeV
6 GeV
E158
Q-Weak (ep)
Moller (ee)
Kurylov, RM, Su
Hyrodgen APV or isotope ratios
Global fit: MW, APV, CKM, l2,…
Effective PV e-q interaction & PVDIS
Low energy effective PV eq interaction
PV DIS eD asymmetry: leading twistWeak Charge:
Nu C1u + Nd C1d
Proton:
QWP = 2 C1u + C1d = 1-4 sin2W ~ 0.1
Electron:
QWe = C1e = -1+4 sin2W ~ - 0.1
PVES, New Physics, & the LHC
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Z 0
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˜ χ −
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˜ χ +€
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˜ χ 0
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˜ e −
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Z 0
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˜ q Lj
1j1
1j1
Radiative Corrections
RPV
SUSY Z/ Bosons Leptoquarks
Doubly Charged Scalars
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′Z
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f€
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e−
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LQ
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˜ q Lj
hee
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< 1.5 TeV Masses
~ few 100 GeV & large tan
Moller: ~ 2.5% on APV
PVDIS: ~ 0.5% on APV
Need L ~ 1033 - 1034
Deep Inelastic PV: Beyond the Parton Model & SM
e-
N X
e-
Z* γ*
d(x)/u(x): large x Electroweak test: e-q couplings & sin2W
Higher Twist: qq and qqg correlations
Charge sym in pdfs
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up (x) = dn (x)?
d p (x) = un (x)?
PVDIS & QCD
Low energy effective PV eq interaction
PV DIS eD asymmetry: leading twist
Higher Twist (J Lab)
CSV (J Lab, EIC)
d/u (J Lab, EIC) +
PVDIS & CSV
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up (x) = dn (x)?
d p (x) = un (x)?
•Direct observation of parton-level CSV would be very exciting!•Important implications for high energy collider pdfs•Could explain significant portion of the NuTeV anomaly
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δu(x) = up (x) − dn (x)
δd(x) = d p (x) − un (x)
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RCSV =δAPV (x)
APV (x)= 0.28
δu(x) −δd(x)
u(x) + d(x)
Londergan & Murdock
Few percent δA/A
Adapted from K. Kumar
PVDIS & d(x)/u(x): xK1
Adapted from K. Kumar
SU(6): d/u~1/2Valence Quark: d/u~0
Perturbative QCD: d/u~1/5
PV-DIS off the proton(hydrogen target)
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APV =GFQ2
2παa(x) + f (y)b(x)[ ]
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a(x) =u(x) + 0.91d(x)
u(x) + 0.25d(x)
Very sensitive to d(x)/u(x)
δA/A ~ 0.01
C-Odd SD Structure Functions
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C-odd
C-odd
Anselmino, Gambino, Kalinowski ‘94
Target Spin Asymmetries
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Polarized Long & trans target spin asymmetries (parity even)
Unpolarized Long & trans target spin asymmetry (parity odd)
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Bilenky et al ‘75; Anselmino et al ‘94
PVES at an EIC
Scale-dependence of Weak Mixing
JLab Future
SLAC Moller
Parity-violating electron scattering
EIC PVDIS ?
Z0 pole tension
EIC Moller ?
Charged Current Processes
• The NuTeV Puzzle
• HERA Studies
• W Production at an EIC ? CC/NC ratios ?
Weak Mixing in the Standard Model
Scale-dependence of Weak Mixing
JLab Future
SLAC Moller
nucleus deep inelasticscattering
Z0 pole tension
The NuTeV Puzzle
Rν =σνNNC σνN
CC =gL2 +rgR
2
Rν =σν NNC σ ν N
CC =gL2 +r−1gR
2
gL,R2 =
ρνNNC
ρνNCC
⎛
⎝ ⎜ ⎞
⎠ ⎟
2
(εL ,Rq
q∑ )2
r =σνNCC σν N
CC
Rνexp−Rν
SM =−0.0033±0.0007
Rν exp−Rν
SM =−0.0019±0.0016
R− =
Rν −rRν
1−r=(1−2sin2θW) /2+L
Paschos-Wolfenstein
SUSY Loops
RPV SUSY
Wrong sign
Other New CC Physics?
Low-Energy Probes
Nuclear & neutron decay
Pion leptonic decay
Polarized μ-decay
δO / OSM ~ 10-3
δO / OSM ~ 10-4
δO / OSM ~ 10-2
HERA W production
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δO / OSM ~ 10-1
A. Schoning (H1, Zeus)
CC Structure Functions: more promising?
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Summary
• Precision studies and symmetry tests are poised to discovery key ingredients of the new Standard Model during the next decade
• There may be a role for an EIC in the post-LHC era
• Promising: PV Moller & PV DIS for neutral currents
• Homework: Charged Current probes -- can they complement LHC & low-energy studies?
• Intriguing: LFV with eK conversion:
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L dt ~ 103 fb∫
Back Matter
• Precision studies and symmetry tests with neutrons are poised to discovery key ingredients of the new Standard Model during the next decade
• Physics “reach” complements and can even exceed that of colliders: dn~10-28 e-cm ; δO/OSM ~ 10-4
• Substantial experimental and theoretical progress has set the foundation for this era of discovery
• The precision frontier is richly interdisciplinary: nuclear, particle, hadronic, atomic, cosmology
PVES Probes of RPV SUSY
111/ ~ 0.06 for mSUSY ~ 1 TeV
sensitivity
k31 ~ 0.15 for mSUSY ~ 1 TeV
μ->eγ LFV Probes of RPV:
k31 ~ 0.03 for mSUSY ~ 1 TeV
μ->e LFV Probes of RPV:
12k ~ 0.3 for mSUSY ~ 1 TeV & δQWe / QW
e ~ 5%
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k31 ~ 0.02 for mSUSY ~ 1 TeV
m LNV Probes of RPV:
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Probing Leptoquarks with PVES
General classification: SU(3)C x SU(2)L x U(1)Y
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Q-Weak sensitivities:
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SU(5) GUT: m
, prot
LQ 2 15H
Dorsner & Fileviez Perez, NPB 723 (2005) 53
Fileviez Perez, Han, Li, R-M 0810.4238
Probing Leptoquarks with PVES
SU(5) GUT:
mvia type II
see saw LQ 2 15H
Fileviez Perez, Han, Li, R-M 0810.4238
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Probing Leptoquarks with PVES
PV Sensitivities
Fileviez Perez, Han, Li, R-M 0810.4238
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4% QWp
(MLQ=100 GeV)
Z Pole Tension
⇒ mH = 89 +38-28
GeV⇒ S = -0.13 ± 0.10
ALR AFB (Z→ bb)
sin2θw = 0.2310(3)
↓mH = 35 +26
-17 GeVS= -0.11 ± 17
sin2θw = 0.2322(3)
↓mH = 480 +350
-230
GeVS= +0.55 ± 17
Rules out the SM! Rules out SUSY!Favors Technicolor!
Rules out Technicolor!Favors SUSY!
(also APV in Cs) (also Moller @ E158)
W. MarcianoThe Average: sin2θw = 0.23122(17)
3σ apart
•Precision sin2W measurements at colliders very challenging•Neutrino scattering cannot compete statistically•No resolution of this issue in next decade
K. Kumar