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Precision Electroweak Physics and QCD at an EIC

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Precision Electroweak Physics and QCD at an EIC

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Precision Electroweak Physics and QCD at an EIC

M.J. Ramsey-Musolf

Wisconsin-Madison

NPAC

Theoretical Nuclear, Particle, Astrophysics & Cosmology

http://www.physics.wisc.edu/groups/particle-theory/

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-+AK - + A
- Neutral Current Processes: PV DIS & PV Moller
- Charged Current Processes: e-+AK ET + j

Disclaimer: some ideas worked out in detail; others need more research

Lepton Number & Flavor Violation

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.

- LNV & Neutrino Mass
- Mechanism Problem
- CLFV as a Probe
- K e Conversion at EIC ?

mnEFF & neutrino spectrum

Theory Challenge: matrix elements+ mechanism

Long baseline

b-decay

?

Normal

Inverted

?

0nbb-Decay: LNV? Mass Term?Dirac

Majorana

Theory Challenge: matrix elements+ mechanism

O(1) for L ~ TeV

0nbb-Decay: MechanismDirac

Majorana

Mechanism: does light nM exchange dominate ?

How to calc effects reliably ? How to disentangle H & L ?

0nbb signal equivalent to degenerate hierarchy

Loop contribution to mn of inverted hierarchy scale

0nbb-Decay: InterpretationSorting 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

Early universe

!e: M1

?

?

Bm->e

R =

!e: M1 !R ~

Bm->eg

Weak scale

Planck scale

CLFV, LNV & the Scale of New PhysicsMEG: Bmg ~ 5 x 10-14

2e: Bm->e ~ 5 x 10-17

Also PRIME

0nbb decay

RPV SUSY

LRSM

Low scale LFV: R ~ O(1)

GUT scale LFV: R ~ O(a)

Lepton Flavor & Number ViolationRaidal, Santamaria; Cirigliano, Kurylov, R-M, Vogel

Tree Level

MEG: Bm->eg ~ 5 x 10-14

Logarithmic enhancements of R

2e: Bm->e ~ 5 x 10-17

BKe48 |A2e|2

M1 operator

|A2e|2 < 10-8

If |A2e|2 ~ |A1e|2

Penguin op

EIC: ~ 10-5 fb

Log or tree-level enhancement:

|A1e|2 / |A2e|2 ~ | ln me / 1 TeV |2 ~ 100

Need ~ 1000 fb

Logarithmic enhancements of R

Lepton Flavor & Number ViolationRaidal, Santamaria; Cirigliano, Kurylov, R-M, Vogel

Exp: B->eg ~ 1.1 x 10-7

EIC: ~ 103 | A1e|2 fb

CLFV & Other Probes

Doubly Charged Scalars

Ke(

Ke(

he hee

+ h he

+ h he

hee he

+ he h

+ he h

Exp: B->eg ~ 1.1 x 10-7

if RH; PV Moller if LH

All hab$ m if part of see-saw

LHC: BRs (in pair prod)

EIC: ~ 103 | A1e|2 fb

eqq eff op

LFV with leptons: HERALeptoquark Exchange: Like RPV SUSY /w /

- HW Assignment:
- Induce Keat one loop?
- Consistent with BKe? HERA limits look stronger
- Connection w/ m & in GUTS ?
- Applicable to other models that generate tree-level ops?

Veelken (H1, Zeus) (2007)

lq|2 < 10-4 (MLQ / 100 GeV)2

qq eff op

lq|2 < 2 x 10-2 (MLQ / 100 GeV)2

LFV with leptons: recent theoryKanemura et al (2005)

SUSY Higgs Exchange

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

Enhanced transparency to new physics

Small QCD uncertainties (Marciano & Sirlin; Erler & R-M)

QCD effects (s-quarks): measured (MIT-Bates, Mainz, JLab)

PV Electron ScatteringParity-Violating electron scattering

Nu C1u + Nd C1d

Proton:

QWP = 2 C1u + C1d = 1-4 sin2W ~ 0.1

Electron:

QWe = C1e = -1+4 sin2W ~ - 0.1

Effective PV e-q interaction & QWLow energy effective PV eq interaction

Large logs in

Sum to all orders with running sin2W & RGE

sin2

Normalization

Scale-dependent effective weak mixing

Constrained by Z-pole precision observables

Flavor-independent

QW and Radiative CorrectionsTree Level

Radiative Corrections

SLAC Moller

Z0 pole tension

Parity-violating electron scattering

Scale-dependence of Weak Mixing

Weak Mixing in the Standard ModelSemi-leptonic only

Moller only

1j1

1j1

hee

hee

PVES & New PhysicsSUSY

Z/ Bosons

Leptoquarks

Doubly Charged Scalars

Radiative Corrections

RPV

RPV: No SUSY DM Majorana n s

SUSY Loops

Q-Weak (ep)

d QWP, SUSY / QWP, SM

d QWe, SUSY / QWe, SM

Hyrodgen APV or isotope ratios

gm-2

12 GeV

6 GeV

E158

Global fit: MW, APV, CKM, l2,…

Kurylov, RM, Su

PVES & APV Probes of SUSYNu C1u + Nd C1d

Proton:

QWP = 2 C1u + C1d = 1-4 sin2W ~ 0.1

Electron:

QWe = C1e = -1+4 sin2W ~ - 0.1

Effective PV e-q interaction & PVDISLow energy effective PV eq interaction

PV DIS eD asymmetry: leading twist

Model Independent Constraints

P. Reimer, X. Zheng

Moller: ~ 2.5% on APV

PVDIS: ~ 0.5% on APV

Need L ~ 1033 - 1034

…

< 1.5 TeV Masses

1j1

1j1

hee

hee

PVES, New Physics, & the LHCSUSY

Z/ Bosons

Leptoquarks

Doubly Charged Scalars

Radiative Corrections

RPV

Higher Twist: qq and qqg correlations

e-

e-

*

Z*

X

N

Charge sym in pdfs

d(x)/u(x): large x

Electroweak test: e-q couplings & sin2qW

Deep Inelastic PV: Beyond the Parton Model & SMCSV (J Lab, EIC)

d/u (J Lab, EIC)

+

PVDIS & QCDLow energy effective PV eq interaction

PV DIS eD asymmetry: leading twist

PVDIS & CSV

- 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

Few percent A/A

Adapted from K. Kumar

d/u~1/2

Valence Quark:

d/u~0

Perturbative QCD:

d/u~1/5

PVDIS & d(x)/u(x): xK1Adapted from K. Kumar

A/A ~ 0.01

Very sensitive to d(x)/u(x)

PV-DIS off the proton

(hydrogen target)

Target Spin Asymmetries

Polarized Long & trans target spin asymmetries (parity even)

Unpolarized Long & trans target spin asymmetry (parity odd)

Bilenky et al ‘75; Anselmino et al ‘94

SLAC Moller

EIC PVDIS ?

Z0 pole tension

EIC Moller ?

Parity-violating electron scattering

Scale-dependence of Weak Mixing

PVES at an EICCharged Current Processes

- The NuTeV Puzzle
- HERA Studies
- W Production at an EIC ? CC/NC ratios ?

SLAC Moller

Z0 pole tension

nucleus deep inelasticscattering

Scale-dependence of Weak Mixing

Weak Mixing in the Standard ModelCC Structure Functions: more promising?

Other New CC Physics?Low-Energy Probes

Nuclear & neutron decay

O / OSM ~ 10-3

Pion leptonic decay

O / OSM ~ 10-4

O / OSM ~ 10-2

Polarized -decay

HERA W production

O / OSM ~ 10-1

A. Schoning (H1, Zeus)

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:

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 ; O/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

0nbb sensitivity

m

LNV Probes of RPV:

l111/ ~ 0.06 for mSUSY ~ 1 TeV

lk31 ~ 0.02 for mSUSY ~ 1 TeV

m->eg

m->e

LFV Probes of RPV:

LFV Probes of RPV:

l12k ~ 0.3 for mSUSY ~ 1 TeV & dQWe/ QWe ~ 5%

lk31 ~ 0.03 for mSUSY ~ 1 TeV

lk31 ~ 0.15 for mSUSY ~ 1 TeV

PVES Probes of RPV SUSYSU(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 PVESGeneral classification: SU(3)C xSU(2)L x U(1)Y

Q-Weak sensitivities:

Probing Leptoquarks with PVES

SU(5) GUT:

mvia type II see saw

LQ 2 15H

Fileviez Perez, Han, Li, R-M 0810.4238

4% QWp (MLQ=100 GeV)

Probing Leptoquarks with PVESPV Sensitivities

Fileviez Perez, Han, Li, R-M 0810.4238

Z Pole Tension

The Average: sin2θw = 0.23122(17)

⇒ mH = 89 +38-28 GeV

⇒ S = -0.13 ± 0.10

3σ apart

Rules out Technicolor!

Favors SUSY!

ALR

AFB (Z→ bb)

(also APV in Cs)

(also Moller @ E158)

sin2θw = 0.2322(3)

↓

mH = 480 +350-230 GeV

S= +0.55 ± 17

sin2θw = 0.2310(3)

↓

mH = 35 +26-17 GeV

S= -0.11 ± 17

Rules out SUSY!

Favors Technicolor!

Rules out the SM!

- Precision sin2W measurements at colliders very challenging
- Neutrino scattering cannot compete statistically
- No resolution of this issue in next decade

K. Kumar