20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst...

48
20 May 2006 Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ ΜΗΛΟΣ

Transcript of 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst...

Page 1: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Conclusions and PerspectivesKrishna KumarUMass Amherst

PAVI0620 May 2006

ΜΗΛΟΣΜΗΛΟΣ

Page 2: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Acknowledgements

• Many thanks for the invitation:– K. De Jager, S. Kox, D. Lhuillier, F. Maas, S. Page, C. Papanicolas, S. Stiliaris

• Ideal workshop setting:– Great location, organization and staff

• Excellent Scientific Program:– Many exciting and interconnected subfields

Pictures, thoughts and ideas from:B. Holstein, K. Paschke, M.J. Ramsey-Musolf, P. Souder, M.

Vanderhaeghenand all the speakers

Page 3: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Come On!

• Many thanks for the invitation:– Thanks for a sleepless week!

• Ideal workshop setting:– How are you supposed to get anything done?!

– Didn’t you know this island has good ouzo?!

• Excellent Scientific Program:– Hey, I did’nt know it was going to be this broad when I accepted! You tricked me!!!

• But I learned a lot….

DisclaimerI am a dumb experimentalist: The following is a personal view

of the status of the field and its immediate future. I apologize in advance for any omissions

Page 4: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Neutral Weak Interactions• The 50’s

– Yang-Mills Theory– Zel’dovich and parity violation

• The 60’s– Weinberg and SU(2)L X U(1)Y Theory: the Z boson

• The 70’s– Neutrino electron scattering– Prescott and Weak Electromagnetic Interference

• The 80’s– Observation of W and Z bosons– Atomic Parity Violation– High statistics parity violating electron scattering– Beginning of the LEP/SLC era: Z factories

Low Energy WNC Interactions address a whole range of physics topics:since the 90s, it has become a precision tool

Page 5: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

WNC Interconnections

Atomic Physics

Nuclear PhysicsNucleon Physics

Valence Quark Physics

Electroweak Physics

Page 6: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

The Beginnings

• Gargamelle: neutrino scattering– First weak neutral current observation– Became centerpiece of electroweak theory

• SLAC E122: Parity-violating Electron Scattering– Central to establishing SU(2)LXU(1)Y

– Established the experimental technique

Gargamelle found one e- event in 1973! (two more by 1976)

Parity is violated Parity is conserved 10 billion events!

Page 7: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Weak Neutral Currents

and the Atom

Page 8: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Atomic Parity Violation

Power build-up cavity ( F=100 000 )

dye laser

beam

ex

E

B

Reexcitation of the depleted HF levell

depletes one HF

level

Bp

p

polarizes the atoms

|F,m=±F>

diode laser, tuned to the depleted HF

level APV signal: odd in E, ex, B, Bp, p

I fluo

Boulder Experiment

Derevianko, Lintz, Gwinner, Chardonnet, Budker, Sanguinetti, Tsigutkin

Tremendous interest in weak charge, anapole moment and EDM measurements in the larger physics community

Ecole Normale Supérieure, Paris

Page 9: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Atomic Parity ViolationElectric and magnetic fields define handedness

CollimatorYtterbium atoms

Oven

PBC mirror

Parabolic reflector

Lightguide

BE

zx

y

Photo-multiplier tubes

Electric field plates

Magnetic field coils

408-nm light

649-nm lightε

( )( )Rotational Invariant: B E Bε ε⋅ × ⋅r r rr r

Berkeley Yb Apparatus Anapole MomentWe also heard from:•A. Derevianko with a nice theoretical overview•C. Chardonnet with an update on the search for parity violation in molecules•G. Gwinner with an update on Francium APV and anapole moment measurement preparations•S. Sanguinetti on the TRAP-RAD experiment to trap Francium

Budker, Tsigutkin

Two comments:•It would be interesting to see another nonzero anapole moment, though connections to N-N interaction seem challenging•Is it worth doing the isotope measurements to access the neutron radius by assuming the Standard Model? There is tremendous interest in obtaining more information.

Page 10: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Weak Neutral Currents

and the Nucleus

Page 11: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Hadronic PV EFTLong Range Medium Range

π

π

+L

π

+L

+L

Short Range

π

π

π

π

+

mN λ pp = −1.22 AL (r p p)

mN ρ t = − 9.35 AL (r n p → dγ)

mN λ pn = 1.6 AL (r p p) − 3.7 AL (

r p α ) + 37 Aγ (

r n p → dγ ) − 2 Pγ (

r n p → dγ)

mN λ t = 0.4 AL (r p p) − 0.7 AL (

r p α ) + 7 Aγ (

r n p → dγ ) + Pγ (

r n p → dγ)

mN λ nn = 1.6 AL (r p p) − 0.7 AL (

r p α ) + 33.3 Aγ (

r n p → dγ ) −1.08 Pγ (

r n p → dγ)+ 0.83

dφnα

dz

Pionless th’y: 5 exp’ts Dynamical pions: 7 exp’ts

Done

NIST,SNS

LANSCE, SNS

HARD*

Ab initio few-body calculation required

Ramsey-Musolf, Holstein, Schiavella, Desplanques, Hyun

Page 12: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Hadronic PV ExperimentsBowman, Snow

y

z

HelicityComponents

Transverse Polarization

OpticalRotation

φ

Medium withParity Violation

N-4He Spin Rotation Experiment

We also heard about the npd at LANSCENew versions of these experiments will be launched at the Spallation Neutrion Source Theoretical developments and the SNS have allowed

these experiments to gather new momentum

Page 13: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Probing Neutron-Rich Matter

QpEM ~ 1 Qn

EM ~ 0

QpW ~ 1 - 4sin2WQn

W ~ 1

Constrain neutron halo for APV

Constrain neutron star crust thickness

Piekerewicz, Michaels

Page 14: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

PREx at Jefferson Lab

A technically demanding measurement:

•Rate ~ 2 GHz•Separate excited state at 2.6 MeV•Stat. Error ~ 15 ppb•Syst. Error ~ 1 to 2 %

Data collection at JLab Hall A likely in 2008

(APV) ~ 3% (Rp-Rn) ~ 1% Q2 ~ 0.01 GeV2 APV ~ 0.5 ppm

Pb

C

208

12

Diamond Backing:

• High Thermal Conductivity• Negligible Systematics

beam

•Tight control of beam properties•New “warm” septum•New 18-bit ADC•New radiation-hard detector•Polarimetry upgrade

Piekerewicz, Michaels

Page 15: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Weak Neutral Currents

and the Nucleon

Page 16: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Nucleon Structure & StrangenessQCD is intractable at low Q2; what is its relationship to hadron structure?

Why don’t sea quarks destroy Quark Model predictions?

Strange quarks are relatively light

What can we say about its role? Neutrino deep inelastic scattering

Δs ~ N s γ μγ 5s N

Breaking of SU(3) flavor symmetry introduces uncertainties

Semi-inclusive: Δs = 0.03 ± 0.03 fragmentation function

Strange mass: 0-20% πN scattering:

Schaefer, Leader, Procureur

Page 17: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Elastic Electroweak Scattering

Kaplan & Manohar (1988)McKeown (1990)

GEs(Q2), GM

s(Q2)

p

AMEF AAAQGA

σπα++

⎥⎦

⎤⎢⎣

⎡−=

24

2~ few parts per millionproton:

Forward angle Backward angle

( ) eA

pMWA

ZM

pMM

ZE

pEE GGAGGAGGA '2sin41 , , εθτε −−===

Helium: Unique GE sensitivityDeuterium: Enhanced GA sensitivity

Armstrong, Real, Baunack, Kox, Glaeser, Moffit

Page 18: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Overview of Experiments

Electron Beam

LH2 Target

SuperconductingCoils

Particle Detectors

GMs, (GA) at Q2 = 0.1 GeV2

SAMPLE

HAPPEX GEs + 0.39 GM

s at Q2 = 0.48 GeV2

GEs + 0.08 GM

s at Q2 = 0.1 GeV2

GEs at Q2 = 0.1 GeV2 (4He)

A4

open geometry, integrating

GEs + 0.23 GM

s at Q2 = 0.23 GeV2

GEs + 0.10 GM

s at Q2 = 0.1 GeV2

GMs, GA

e at Q2 = 0.1, 0.23, 0.5 GeV2

Open geometry

Fast counting calorimeter for background rejection

G0

GEs + GM

s over Q2 = [0.12,1.0] GeV2

GMs, GA

e at Q2 = 0.23, 0.62 GeV2

Open geometry

Fast counting with magnetic spectrometer + TOF for background rejection

Armstrong, Real, Baunack, Kox, Glaeser, Moffit

Page 19: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Current StatusOver the past two years:New data from A4, G0 and HAPPEX

Q2 ~ 0.1 GeV2

•Forward angle data nearly finished•One high precision point at Q2~0.6•Await backward angle measurements from A4, G0•Deuterium running will provide constraints on GA

Page 20: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Strangeness Theory

• Quark Model (Riska)– While the ss-bar component is very compact, specific 5 quark states (with s-bar in the ground state) leads to positive GM

s

• Chiral Quark Soliton Model (Goeke)– Interesting Q2 dependence will be tested soon!

• Heavy Quark Contribution (Toublan)– Raises the issue of the sign of the disconnected light and heavy quark loops

• VMD Approach (Bijker, Dubnicka)– Some sensitivity to the assumed asymptotic behaviour of the strange form factors

• Lattice Gauge Theoretic Approach (Zanotti, Young)– Nice way to access sea quark dynamics, but a critical component involves a hadronic model without consensus on the assigned error

Strangeness in the nucleon has challenged model builders for two decades

Page 21: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Axial Form Factor•Neutrino oscillations experiments need accurate cross-sections•Discrepancy between neutrino and electroproduction data understood•PV experiments need Q2 dependence for backward angle measurements

Minerva will make accurate measurements

Bodek, Schindler

Page 22: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Charge Symmetry BreakingChiral perturbation theory with resonance saturation

Lewis

Page 23: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Nucleon EM Form Factors

BLAST at MIT-Bates

Low Q2 data critical to reduce systematic error in extraction of Gs

Alarcon, Pacetti, Dubnicka

Page 24: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Personal Outlook• Forward Angle

– Fast variation in the range 0<Q2<0.3 GeV2 ruled out by latest HAPPEX data– Still a window to see non-zero strangeness at Q2~0.6 GeV2

– Charge symmetry, radiative corrections and EM form factor uncertainties preclude any further precision at any Q2

• Backward Angle– New G0 and A4 data sensitive to cancellations at intermediate Q2

– Knowledge of GA and background asymmetries will limit further precision than already proposed

• Theory– Models are challenged in dealing with properties purely of the sea– Ultimate insight must come from unquenched lattice calculations with light

chiral quarks• Where are we?

– We have answered a 20 year-old question about nucleon structure: do strange quark contribute to the charge and magnetization distributions of nucleons? The answer seems to be: smaller than expected but we have to complete the approved program. Beyond that, it is in the realm of lattice QCD.

Page 25: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Beam-Normal Asymmetriesbeam :'

'

•Imaginary part of two-photon exchange amplitude•“background” for parity-violation experiments

Vanderhaeghen, Pasquini, Kaufman, Capozza

A4 Preliminary at 300 MeV

Page 26: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Beam-Normal Asymmetries at JLabKaufman, Vanderhaeghen

First measurement on a nucleus

Hydrogen target

11 GeV beam at different Q2 values

HAPPEX

HAPPEX

Page 27: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Gluon Polarization

or

lepton beam

or

nucleon target

heavy flavor, high pT

or

or

proton beam

proton beam

π0, (PHENIX),jets (STAR)

STARSTAR

•Strangeness and gluon polarization are the only two “purely sea” experimentally accessible observables•RHIC and lepton DIS experiments both agree ΔG is small•They will make inroads, but the ultimate measurements will require a lepton-ion collider: obtain ΔG directly and by DGLAP evolution of g1

Leader, Proceureur

Page 28: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Weak Neutral Currents

and the Valence Quark

Page 29: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

NuTeV Anomaly

Assumptions:• Isoscalar target (N=Z)• include only light (u, d) quarks• neglect heavy quark masses• assume isospin symmetry for PDFs • no nuclear effects (parton shadowing, EMC, ….)• no contributions outside Standard Model

3σ below SM

agree with SM

After ~ three years, no consensus yet

No “good” new physics scenario

Community Prejudice: some combination of isospin violation, nuclear effects, strangeness asymmetry and systematics on radiative corrections

Londergan

Page 30: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

PV DIS

C1i ≡ 2gAe gV

i

C2i ≡ 2gVe gA

i€

APV =GFQ2

2παa(x) + f (y)b(x)[ ]

a(x) =

C1iQi f i(x)i

Qi2 f i(x)

i

b(x) =

C2iQi f i(x)i

Qi2 f i(x)

i

• Charge Symmetry Violation– Partonic level CSV has never been observed– Needs high precision with inclusive scattering

• d(x)/u(x) at as x 1– Longstanding QCD prediction– Needs high precision without nuclear effects

• Higher Twist– Absence of significant higher twist a surprise– Needs high precision on “predictable” reaction

Address outstanding issues in high x physics

Reimer, Souder, Zheng

Page 31: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

1% APV

measurements

PV DIS with JLab UpgradeCharge Symmetry Violation at High x: clean observation possible

u(x) = up (x) − dn (x)

δd(x) = d p (x) − un (x)

For an isoscalar target like 2H

a(x) =3

10(2C1u − C1d )[ ] +L

b(x) =3

10(2C2u − C2d )

uv (x) + dv (x)

u(x) + d(x)

⎣ ⎢ ⎤

⎦ ⎥+L

APV (x)

APV (x)= 0.3

δu(x) −δd(x)

u(x) + d(x)

Global fits allow x3 larger effects

APV =GFQ2

2παa(x) + f (y)b(x)[ ]

a(x) =u(x) + 0.91d(x)

u(x) + 0.25d(x)

•Allows d/u measurement on a single proton!•Vector quark current! (electron is axial-vector)

Longstanding issue: d/u as x1

For hydrogen 1H:

Souder, Londergan

Page 32: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

A Vision for PV DIS Physics• Hydrogen and Deuterium targets• Better than 2% errors

– It is unlikely that any effects are larger than 10%

• x-range 0.25-0.75• W2 well over 4 GeV2

• Q2 range a factor of 2 for each x point– (Except x~0.75)

• Moderate running times

•CW 90 µA at 11 GeV•40 cm liquid H2 and D2 targets•Luminosity > 1038/cm2/s

•solid angle > 200 msr•Count at 100 kHz• online pion rejection of 102 to 103

Goal: Form a collaboration, start real design and simulations, and make pitch to US community at the next nuclear physics long range plan (2007)

Souder

Page 33: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Weak Neutral Currents

and TeV Physics Beyond the Standard Model

Page 34: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Beyond Standard Model @ Low Q2

•Precise predictions @ 0.1%•Indirect access to TeV scale•World electroweak data has marginal 2, but no

discernable pattern•Data used to put limits on energy scale of new physics effects•Parity-conserving contact interactions probed

at 20-30 TeV level•Parity-violating contact interactions probed at 5-10 TeV level

KK

Page 35: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

SLAC E158sin2eff = 0.2397 ± 0.0010 ± 0.0008

APV = (-131 ± 14 ± 10) x 10-9

* Limit on LL ~ 7 or 16 TeV

* Limit on SO(10) Z’ ~ 1.0 TeV* Limit on lepton flavor violating coupling ~ 0.01GFEnd of the SLAC Fixed Target Program

KK

Page 36: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

The LHC

• LHC to begin data collection in 2008• Focus is on EW symmetry breaking

– Standard Model Higgs hard below 150 GeV and above 500 GeV

• Energy frontier: look for the unexpected– The unexpected at LHC likely to remain ill-defined!– The more obscure the signal, the more important are low energy constraints!

• Electroweak Physics at the LHC– Factor of 3 improvement in W Mass– Factor of 5 improvement in Top Mass– Weak Mixing Angle: Improve constraints on new parity-conserving contact interactions

Erler

Page 37: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Qweak at JLab

Region 3: Vertical Drift chambers

Region 2: Horizontal

drift chamber location

Region 1: GEMGas Electron Multiplier Quartz Cerenkov Bars

(insensitive to non-relativistic particles)

Collimator System

Mini-torus

QTOR Magnet

Trigger Scintillator

Lumi Monitors

e- beam

C1i’s measured to unprecedented precision

•Design, simulation, prototyping, construction•Installation in 2009•Complementary to LHC•Important constraint should LHC see anomaly

MNC

Page

Page 38: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Beyond SM with PV DISFor an isoscalar target like 2H,

structure functions largely cancel in the ratio:

a(x) =3

10(2C1u − C1d )[ ] +L

b(x) =3

10(2C2u − C2d )

uv (x) + dv (x)

u(x) + d(x)

⎣ ⎢ ⎤

⎦ ⎥+L

(Q2 >> 1 GeV2 , W2 >> 4 GeV2, x ~ 0.3-0.5)

Complementary to LHC

•Need to characterize nucleon structure at high-x to high precision•6 GeV experiment launches PV DIS measurements at JLab•12 GeV experiment requires tight control of normalization errors•Important constraint should LHC see anomaly

Zheng, Reimer

Page 39: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Møller Scattering @ 12 GeV

Address longstanding discrepancy between hadronic and leptonic Z asymmetries

Z pole asymmetries

•Comparable to single Z pole measurement: shed light on disagreement•Best low energy measurement until ILC or -Factory •Could be done ~ 2012-13

Mack

Page 40: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Ultrahigh Precision at ILC

(world average ~0.00016)

Measure contribution from scalars to oblique corrections

ALR and MW at future colliders:

Systematics extremely challenging!

t

Z

H

b

new

physics

Critical crosscheck

Energy scale to 10-4, polarimetry to 0.15%

E158 LC

Energy (GeV) 48 250-500

Intensity/pulse 4.5 1011 14 1011

Pulse Rate (Hz) 120 120

Pe 85% 90%

Time (s) 4 106 2 107

ALR (ppm) 0.15 1-2

ALR (ppm) 0.015 0.008

sin2(W) 0.001 0.00008

K.K, Snowmass 96

• Fixed target has advantages for systematics• Could work with ILC “exhaust”beam

Møller scattering at the ILC

mH

mH

≈10% for δ sin2 θW ≈ 0.00004

KK

Page 41: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Theoretical Challenges• Hadron Structure Theory (A. Schäfer)

– Era of precision QCD requires major effort– Examples of NNLO convergence (e.g. DVCS)– Lattice QCD should enter the realm of dynamical chiral quarks– Balanced effort in perturbative QCD, chiral perturbation theory and Lattice QCD

• Low Energy EW Measurements & Loops (W. Marciano)– Gamma-Z and Gamma-W boxes for semi-leptonic processes– Improved calculation of super-allowed beta decays– Future applications: APV, neutrino scattering…

• Future Directions (M. Ramsey-Musolf)– Probing higher-twist effects in PVDIS: precision measurements with improved leading-twist predictions

– EFT approach to few-body hadronic parity violation– SUSY implications of precision low energy EW measurements– CP and T violation probes via EDM with implications for dark matter and the primordial baryon asymmetry

Page 42: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Parity Violating Electron Scattering

Experimental Challenges

Page 43: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Polarized Source ControlsΔΔx’x’

micron

4Δ4Δ

4*ppm

Grand average: ~ 1 nm

Grand average: ~ 0.25 ppb

HAPPEX Position Differences during run with hydrogen target

Pulser

diode-laser

Lock-in

Sw.

PC Movable Detektor with pinhole

Aulenbacher, Pashke

More and more demanding and ambitious with every run!

Page 44: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Cryogenic Targets

G0 targetat Jlab

E158 at SLAC

Requirements are becoming ever-demanding!

Page 45: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Polarimetry Diefenbach, Mack

Hydrogen: 86.7% ± 2%

Signal from A4 Compton Polarimeter

HAPPEX Hydrogen Run

•High future demands for sub-1% polarimetry: Critical to have redundancy•Promising techniques: “high-field” Moller and Atomic Hydrogen polarimetry

Page 46: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Where are we going?

Atomic Physics

Nuclear PhysicsNucleon Physics

Valence Quark Physics

Electroweak Physics

We will continue to learn a whole lot along the way

Page 47: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Personal ThoughtsStudies of Weak Neutral Current Interactions touches on extraordinarily rich and diverse topics

We learn to appreciate physics over all length scales and there is much left to learn over the full range

What strikes me in these PAVI meetings is that the participants are not particle or nuclear or atomic physicists

We are physicists

I look forward to many more rewarding interactions with you at the next PAVI!!!

Page 48: 20 May 2006Conclusions & Perspectives Conclusions and Perspectives Krishna Kumar UMass Amherst PAVI06 20 May 2006 ΜΗΛΟΣ.

20 May 2006 Conclusions & Perspectives

Not into the sunset!