Transcript Parity Violation in eP Scattering at JLab

Parity and the JLab 12 GeV Upgrade:
The Program for Hall A
Hadronic and Electroweak Physics
Moller and DIS Parity
Thanks to Bosted, Brodsky, Kumar,
Londergan, Meziani, Michaels,
Reimer, Ramsey-Musolf,
Paschke, Pitt, Zheng
June 24, 2005
DIS Parity
P. A. Souder
Syracuse University
P. A. Souder
Outline
• Parity-Violating Electron Scattering
– Brief Overview
– Weak Neutral Current Interactions at Q2<<MZ2
• Parity-Violating Møller Scattering
– Ultimate Precision at Q2<<MZ2: 25 TeV Reach
– Complementary to Qweak
• Parity-Violating Deep Inelastic Scattering
–
–
–
–
New Physics at 10 TeV in Semileptonic Sector
Charge Symmetry Violation
d/u at High x
Higher Twist Effects
June 24, 2005
DIS Parity
P. A. Souder
PV Asymmetries
Weak Neutral Current (WNC) Interactions at Q2 << MZ2
Longitudinally Polarized
Electron Scattering off
Unpolarized Fixed Targets
(gAegVT + gVegAT)
•The couplings g depend on electroweak physics as well as on the
weak vector and axial-vector hadronic current
•With specific choice of kinematics and targets, one can probe new
physics at high energy scales
•With other choices, one can probe novel aspects of hadron structure
June 24, 2005
DIS Parity
P. A. Souder
APV Measurements
APV ~ 105  Q2 to

104  Q2
0.1 to 100 ppm

• Steady progress in technology
• part per billion systematic control
• 1% normalization control
•JLab now takes the lead
-New results from HAPPEX
-Photocathodes
-Polarimetry
-Targets
-Diagnostics
-Counting Electronics
E-05-007
June 24, 2005
DIS Parity
e2e
P. A. Souder
The Standard Model
June 24, 2005
DIS Parity
P. A. Souder
(it just wont break!)
The Annoying Standard Model
Nuclear Physics Long Range Plan:
What is the new standard model?
Low Q2 offers unique and complementary probes of new physics
•Rare or Forbidden Processes
•Symmetry Violations
•Electroweak One-Loop Effects
- Double beta decay..
- neutrinos, EDMs..
- Muon g-2, beta decay..
Input
Output
G0
•Precise predictions at level of 0.1%
•Indirect access to TeV scale physics
•Extra probe of hadrons
June 24, 2005
DIS Parity
P. A. Souder
World Electroweak Data
on sin2θW
Most experts see the
precision data as
remarkably consistent
Are Leptonic and hadronic
Z couplings seem inconsistent?
Perhaps there are bigger deviations lurking elsewhere???
June 24, 2005
DIS Parity
P. A. Souder
Electroweak Physics at Low Q2
Q2 << scale of EW symmetry breaking
Logical to push to higher energies, away from the Z resonance
LEPII, Tevatron, LHC access scales greater than L ~ 10 TeV
Complementary:
June 24, 2005
DIS Parity
P. A. Souder
WNC Low Q2 Processes
Atomic Parity Violation (APV)
APV on Cs
series of isotopes
•Limited by theory: Atomic structure; Neutron Halo
Semi-Leptonic
PV Elastic electron-proton scattering at JLab Qweak
PV Deep Inelastic Scattering at upgraded JLab
NuTeV • PV DIS experiment feasible within scope of HMS/SHMS upgrade
• Unique, complementary probes of New Physics
• Theoretical issues are interesting in themselves:
Unique, outstanding opportunity for a dedicated apparatus with JLab upgrade
Leptonic
-e scattering in reactor
Møller scattering at upgraded JLab
E158 •Reactor experiment cannot do better than SLAC E158
•Dedicated new apparatus at upgraded JLab can do significantly better:
Best low energy measurement until Linear Collider or -Factory
June 24, 2005
DIS Parity
P. A. Souder
Fixed Target Møller Scattering
Purely leptonic reaction
Weak charge of the electron:
QWe ~ 1 - 4sin2W
A PV  me E lab (1 4 sin 2  W )
1

E lab
SLAC E158
Jlab at 12 GeV
(A PV )
(sin 2  W )
 0.05
2
sin  W
A PV
Figure of Merit rises linearly with Elab
- Maximal at 90o in COM (E’=Elab/2)

- Highest
possible Elab with good P2I
- Moderate Elab with LARGE P2I
Unprecedented opportunity: The best precision at Q2<<MZ2 with the least
theoretical uncertainty until the advent of a linear collider or a neutrino factory
June 24, 2005
DIS Parity
P. A. Souder
Present Results and Future Experiments
June 24, 2005
DIS Parity
P. A. Souder
Qeweak : Electron Weak Charge – SLAC E158 Experiment
Parity-violating Moller scattering
Q2 ~ .026 GeV2
 ~ 4 – 7 mrad
E ~ 48 GeV
at SLAC End Station A
Final results: hep-ex/0504049
APV = -131  14 (stat)  10 (syst) ppb
sin2eff(Q2=0.026 GeV2) = 0.2397 ± 0.0010 ±0.0008
Running of sin2eff established at 6 level in pure leptonic sector
June 24, 2005
DIS Parity
P. A. Souder
Design for 12 GeV
E’: 3-6 GeV
lab = 0.53o-0.92o
APV = 40 ppb
Ibeam = 90 µA
150 cm LH2 target
4000 hours
Toroidal spectrometer
ring focus
• Beam systematics: steady progress
(E158 Run III: 3 ppb)
• Focus alleviates backgrounds:
ep  ep(), ep  eX()
• Radiation-hard integrating detector
• Normalization requirements similar
to other planned experiments
• Cryogenics, density fluctuations
and electronics will push the stateof-the-art
Mack, Reimer, at al
June 24, 2005
(APV)=0.58 ppb
DIS Parity
P. A. Souder
New Physics Reach
JLab Møller
Lee ~ 25 TeV
New Contact Interactions
LEP200
Kurylov, Ramsey-Musolf, Su
Lee ~ 15 TeV
Does Supersymmetry (SUSY) provide a
candidate for dark matter?
•Lightest SUSY particle (neutralino)
is stable if baryon (B) and lepton (L)
numbers are conserved
•However, B and L need not be
conserved in SUSY, leading to
neutralino decay (RPV)
June 24, 2005
DIS Parity
P. A. Souder
The Qweak Apparatus
(Calibration Mode Only - Production & Calibration Modes)
Region 1: GEM
Gas Electron Multiplier
Quartz Cherenkov Bars
(insensitive to
non-relativistic particles)
Region 2: Horizontal
drift chamber location
Mini-torus
e- beam
Ebeam = 1.165 GeV
Ibeam = 180 μA
Polarization ~85%
Target = 2.5 KW
Lumi Monitors
QTOR Magnet
Region 3: Vertical
Drift chambers
Collimator System
Trigger Scintillator
June 24, 2005
DIS Parity
P. A. Souder
Qpweak & Qeweak – Complementary Diagnostics for New Physics
JLab Qweak
SLAC E158
-
(proposed)
eu
ue
~Z’
LQ
d
e
Run I + II + III
(preliminary)
±0.006
u
• Qweak measurement will provide a stringent stand alone constraint
on Lepto-quark based extensions to the SM.
• Qpweak (semi-leptonic) and E158 (pure leptonic) together make a
powerful program to search for and identify new physics.
June 24, 2005
DIS Parity
P. A. Souder
Running coupling constants in QED and QCD
QCD(running of s)
QED (running of )
137 
s
What about the running of sin2W?
June 24, 2005
DIS Parity
P. A. Souder
Running of sin2θW
QWe
modified
sin2W runs with Q2
(sin2W) ~ 0.0003
Comparable to single collider measurements
• JLab measurement would
have impact on
discrepancy between
leptonic and hadronic Z-pole
measurements
June 24, 2005
DIS Parity
P. A. Souder
Parity Violation in Deep Inelastic
Scattering
June 24, 2005
DIS Parity
P. A. Souder
Electron-Quark Phenomenology
A
V
C1i  2gAe gVi
V
A
C2i  2gVe gAi
C1u and C1d will be determined to high precision by Qweak, Cs
C2u and C2d are small and poorly known:
 combination can be accessed in PV DIS
one
New physics such as compositeness, new gauge bosons:
Deviations to C2u and C2d might be fractionally large
Proposed JLab upgrade experiment will improve knowledge of 2C2u-C2d
by more than a factor of 20
June 24, 2005
DIS Parity
P. A. Souder
Parity Violating Electron DIS
e-
eZ*
APV
*
X a(x) 
N

GF Q2

a(x)  f (y)b(x)
2
 C Q f (x)
1i
i i
i
Q
2
i i
f (x)
b(x) 
C
2i
Qi f i (x)
i
Q
x  x Bjorken
y 1 E / E
2
i i
f (x)
i
i
fi(x) are quark distribution
functions

 cancel in the ratio:
For an isoscalar target like 2H, structure
functions largely


Provided Q2 >> 1 GeV2 and W2 >> 4 GeV2 and x ~ 0.2 - 0.4
3
a(x)  (2C1u  C1d ) 
10
3 
uv (x)  dv (x) 
b(x)  (2C2u  C2d )

10 
u(x)  d(x) 
Must measure APV to fractional accuracy better than 1%

• 11 GeV at high luminosity makes very high precision feasible
• JLab is uniquely capable of providing beam of extraordinary stability
normalization errors being developed at 6 GeV
• Systematic control of
June 24, 2005
DIS Parity
P. A. Souder
2H
Experiment at 11 GeV
lab = 12.5o
E’: 5.0 GeV ± 10%
60 cm LD2 target
Ibeam = 90 µA
• Use both HMS and SHMS to increase solid angle
• ~2 MHz DIS rate, π/e ~ 2-3
APV = 217 ppm
xBj ~ 0.235, Q2 ~ 2.6 GeV2, W2 ~ 9.5 GeV2
Advantages over 6 GeV:
•Higher Q2, W2, f(y)
•Lower rate, better π/e
•Better systematics: 0.7%
(APV)=0.65 ppm
(2C2u-C2d)=±0.0086±0.0080
Theory: +0.0986
June 24, 2005
1000 hours
DIS Parity
PDG (2004): -0.08 ± 0.24
P. A. Souder
Physics Implications
(2C2u-C2d)=0.012
(sin2W)=0.0009
Unique, unmatched constraints on axial-vector quark couplings:
Complementary to LHC direct searches
Examples:
June 24, 2005
•1 TeV extra gauge bosons (model dependent)
•TeV scale leptoquarks with specific chiral couplings
DIS Parity
P. A. Souder
Why should we believe DISparity
when no one Believes NuTeV?
June 24, 2005
DIS Parity
P. A. Souder
Measuring sin2θW with NuTeV
Paschos & Wolfenstein ( PR D7, 91 (73)):
PW ratio  minimizes sensitivity to PDFs, higher-order corrections
Result is off by 2.8 σ
June 24, 2005
DIS Parity
P. A. Souder
The NuTeV Experiment
Features very large kinematic acceptance
μ
Charged current
Neutral current
June 24, 2005
DIS Parity
P. A. Souder
Assumptions for the Paschos-Wolfenstein Ratio
PW Ratio depends on the following assumptions:
• Isoscalar target (N=Z)
JLab 12 GeV
• include only light (u, d) quarks
issues
• neglect heavy quark masses
• assume isospin symmetry for PDFs
• no nuclear effects (parton shadowing, EMC, ….)
• no higher twist effects
Nobody believes
• radiative corrections OK? (γ-W boxes?)
that this is the
• no contributions outside Standard Model
problem
June 24, 2005
DIS Parity
P. A. Souder
PV DIS can Address Issues Raised by NuTeV
•
Analysis assumed control of QCD uncertainties
– Higher twist effects
– Charge Symmetry Violation (CSV)
– d/u at high x
•
NuTeV provides perspective
– Result is 3 from theory prediction
– Generated a lively theoretical debate
– Raised very interesting nucleon structure issues: cannot be
addressed by NuTeV
•
JLab at 11 GeV offers new opportunities
– PV DIS can address issues directly
• Luminosity and kinematic coverage
• Outstanding opportunities for new discoveries
• Provide confidence in electroweak measurement
June 24, 2005
DIS Parity
P. A. Souder
Search for CSV in PV DIS
u (x)  d (x)?
p
n
d (x)  u (x)?
p
n
u(x)  u p (x)  d n (x)
•u-d mass difference
•electromagnetic effects
d(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
For APV in
electron-2H
DIS:
APV
APV
 0.28
u  d
u d
Sensitivity will be further enhanced if u+d falls off more rapidly than u-d as x  1
Strategy:

•measure or constrain higher twist effects at x ~ 0.5-0.6
•precision measurement of APV at x ~ 0.7 to search for CSV
June 24, 2005
DIS Parity
P. A. Souder
Phenomenological Parton CSV PDFs
MRST Phenomenological PDFs include CSV for 1st time:
Martin, Roberts, Stirling, Thorne (03):
Choose restricted form for parton CSV:
90% conf limit (κ)
[f(x): 0 integral; matches to valence at small, large x]
Best fit: κ = -0.2, large uncertainty !
Best fit remarkably similar to model
CSV predictions
ADEL
MRST
June 24, 2005
DIS Parity
P. A. Souder
Higher Twist Coefficients in parity
conserving (Di) and nonconserving (Ci) Scattering
F2 (x,Q2 )  F2 (x)(1 D(x) /Q2 )
APV (x,Q2 )  APV (x)(1 C(x) /Q2 )


•
•
•

(Does not
Evolve)
APV sensitive to diquarks: ratio of weak to electromagnetic charge depends on
amount of coherence
If Spin 0 diquarks dominate, likely only 1/Q4 effects
Some higher twist effects may cancel in ratio, so APV may have little dependence on
Q2 .
June 24, 2005
DIS Parity
P. A. Souder
Going from LO to NNNLO Greatly Reduces
the Extracted Higher Twist Coefficients
F2(x,Q2)=F2(x)(1+D(x)/Q2)
Q2=(W2-M2)/(1/x-1)
D/Q2min(%)
D/Q2min(%)
LO
NNNLO
0.5
-14
2
0.003
1.0
-11
0.0
-.06
-0.001
1.7
-3.5
-0.5
0.4-0.5
.22
0.11
2.6
8
4
0.5-0.6
.85
0.39
3.8
22
10
0.6-0.7
2.6
1.4
5.8
45
24
0.7-0.8
7.3
4.4
9.4
78
47
x
D(x)
D(x)
LO
NNNLO
0.1-0.2
-.007
0.001
0.2-0.3
-.11
0.3-0.4
Q2min
Q2min=Q2(W=2)
If D(x)~C(x), Parity might show higher twist
At high x without needing QCD evolution.
June 24, 2005
DIS Parity
P. A. Souder

APV in DIS on 1H
APV
GF Q2

a(x)  f (y)b(x)
2
3 2C1u u(x)  C1d (d(x)  s(x)) 
a(x)  

2  4u(x)  d(x)  s(x)


3 2C u (x)  C2d dv (x)
b(x)   2u v

2  4u(x)  d(x)  s(x) 
u(x)  0.91d(x)
+ small corrections
a(x) 

u(x)  0.25d(x)
•Allows d/u measurement on a single proton!
•Vector quark current! (electron is axial-vector)
•Determine that higher twist is under control
•Determine standard model agreement at low x
•Obtain high precision at high x
June 24, 2005
DIS Parity
P. A. Souder
Uncertainties in d/u at High x, and the Errors we
Would Like to Achieve with PV Measurements
Deuteron analysis has nuclear
corrections
APV for the
proton has no such
corrections
Must simultaneously
constrain higher twist effects
The challenge is to get statistical and systematic errors ~ 2%
June 24, 2005
DIS Parity
P. A. Souder
Complete PV DIS Program (Including 12 GeV)
• 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~0.7)
• Moderate running times
•With HMS/SHMS: search for TeV physics
•With larger solid angle apparatus: higher twist, CSV, d/u…
June 24, 2005
DIS Parity
P. A. Souder
Apparatus Needed for PVDIS
June 24, 2005
DIS Parity
P. A. Souder
E05-007: Start PVDIS at 6 GeV (Approved)
R. Michaels (JLab), P. Reimer (ANL), X. Zheng (ANL)
and the Hall A Collaboration
Asymmetry to be measured:
Experimental Setup:
85uA, 6 GeV, “parity-quality” 80% pol. beam;
25-cm LD2 target;
Two HRS detect scattered electrons.
•
Measure Ad at Q2=1.10 and Q2=1.90 (GeV/c)2 to 2% (stat.);
June 24, 2005
DIS Parity
P. A. Souder
Goals at 6 GeV
From Ad at Q2=1.90 (GeV/c)2, can
extract (2C2u-C2d) to an uncertainty of
0.03 (factor of 8 improvement
compared to PDG);
provide constraints on new physics
& test of the Standard Model up to 1
TeV mass limit;
Z' Searches:
Compositeness (4-fermion contacts)
Leptoquarks.
The Ad at Q2=1.10 (GeV/c)2 will help to investigate if there are significant
hadronic (higher-twist) effects: (12 GeV, NuTeV...)
June 24, 2005
DIS Parity
P. A. Souder
Reaching Large x and Large Q2 at 12 GeV
Need Large
θ for large
x and Q2
20    40
6 GeV
E /  4 GeV
HMS and SHMS
are fine for
small θ
0 . 6  y  0. 8
W 2  4 GeV 2
50% azimuthal
coverage assumed
June 24, 2005
DIS Parity
P. A. Souder
June 24, 2005
•2 to 3.5 GeV scattered electrons
•20 to 40 degrees
•Factor of 2 in Q2 range at moderate x
•High statisticsDISatParity
x=0.7, with
W>2
P. A. Souder
Details on Kinematics and π/e Backgrounds
Cut on 0.6<y<0.8
• Large range in Q2 for HT study
• High x (>0.7) accessible with W2>4
• Large acceptance allows feasible runtime requests
• /e ratio is not extreme, but cannot integrate
June 24, 2005
DIS Parity
P. A. Souder
Large Angle Large Acceptance: Concept
JLab Upgrade
•Need high rates at high x
•CW 90 µA at 11 GeV
•40-60 cm liquid H2 and D2 targets
•Luminosity > 1038/cm2/s
•For the first time: sufficient rates to make
precision PV DIS measurements
•solid angle > 200 msr
•Count at 100 kHz
• online pion rejection of 102 to 103
Need toroid to block γ’s and
low energy π’s
June 24, 2005
DIS Parity
P. A. Souder
d/u Measurements for Proton
(Kent Paschke simulation)
A couple weeks of beam time with toroid spectrometer
June 24, 2005
DIS Parity
P. A. Souder
What Physics is Allowed by New Device?
Example: d/u of Proton
Compare MAD Spectr. to Toroid Spectr.
Curves from
Melnithouk
and Thomas
d/u
off shell
on shell
x Bjorken
June 24, 2005
DIS Parity
P. A. Souder
EMC effect in Parity Violation ?
Cross section data from
J. Gomez et.al. PRD 49
(1994) 4348
June 24, 2005
DIS Parity
P. A. Souder
High x Physics Outlook: Context
•
•
•
•
•
•
Parity-Violating DIS can probe exciting new physics at high x
One can start now (at 6 GeV)
– Do 2 low Q2 points (P-05-007, X. Zheng contact)
• Q2 ~ 1.1 and 1.9 GeV2
• Either bound or set the scale of higher twist effects
– Take data for W<2 (P-05-005, P. Bosted contact)
• Duality
• Could help extend range at 11 GeV to higher x
A short run to probe TeV physics in PV DIS off 2H: Hall A or C
The bulk of the program requires a dedicated spectrometer/detector
CSV can also be probed via electroproduction of pions
– 6 GeV beam can probe x ~ 0.45 (P-05-006, K. Hafidi contact)
– Should be able to go to higher x with 12 GeV beam
Other vital physics topics could be addressed by dedicated spectrometer:
– Transverse (beam-normal) asymmetries in DIS
– Polarized targets: g2 and g3 structure functions
– Higher twist studies of A1p and A1n
June 24, 2005
DIS Parity
P. A. Souder
Summary
• 12 GeV Upgrade
– Opens unique opportunities for new PV measurements
– Hall configuration must support dedicated apparatus
• Large solid angle toroid/calorimeter for PV DIS
• Superconducting solenoid for Møller scattering
• Physics Highlights
–
–
–
–
–
Unique Standard Model tests
Unique, clean d/u for proton
Test Charge Symmetry at the Quark level
Observe clean higher twist effects
New probe for EMC effect?
June 24, 2005
DIS Parity
P. A. Souder
Future Directions for PV Moller and APV
e2ePV: Parity-Violating Moller scattering at 12 GeV JLAB
(Mack, Reimer, et al.)
• Achieve Moller focus with long, narrow
superconducting toroidal magnet,
Radiation hard detector package
• E = 12 GeV Q2 =.008 GeV2 ,
 ~ .53 - .92o , APV = - 40 ppb
In 4000 hours, could determine QeW to 2.5%
(compare to 12.4% for E158)
Atomic Parity Violation Future Directions
● Paris group (Bouchiat, et al.): more precise Cs APV
● Seattle group (Fortson, et al.): single trapped Ba+ APV 6S1/2  5D3/2
● Berkeley group (Budker, et al.): isotope ratios in Yb APV
● Stony Brook group (Orozco, et al.): isotope ratios in Fr APV
Note: isotope ratios can eliminate large atomic structure theory uncertainties
June 24, 2005
DIS Parity
P. A. Souder
Overview of the QpWeak Experiment
Elastically
Scattered Electron
Elastically Scattered Electrons
Luminosity
Luninosity
Monitor
Monitors
5 inch PMT in Low Gain
Integrating Mode on Each
End of Quartz Bar
Region III
Drift Chambers
325 cm
Region 3
Drift Chambers
Toroidal Magnet
580 cm
Toroidal Magnet
Region II
Drift Chambers
Region 2
Eight
Fused
Silica (quartz)
(quartz)
Eight
Fused
Silica
Cerenkov Detectors
Čerenkov Detectors
Region I Drift Chambers
GEM Detectors
Region 1
GEM Detectors
Experiment Parameters
(integration mode)
Incident beam energy: 1.165 GeV
Beam Current:
180 μA
Beam Polarization:
85%
LH2 target power:
2.5 KW
Collimator With Eight Openings
Collimator with
 =89openings
± 2°
θ= 8° ± 2°
35 cm Liquid Hydrogen Target
35cm
Liquid
Hydrogen Target
Polarized
Electron
Beam
Polarized Electron Beam
June 24, 2005
Central scattering angle:
Phi Acceptance:
Average Q²:
Acceptance averaged asymmetry:
Integrated Rate (all sectors):
Integrated Rate (per detector):
DIS Parity
P. A. Souder
8.4° ± 3°
53% of 2
0.030 GeV2
–0.29 ppm
6.4 GHz
800 MHz
“Running of sin2W” : Current Status and Future Prospects
12 GeV
QW (e)
present:
“d-quark dominated” : Cesium APV (QAW): SM running verified at ~ 4 level
“pure lepton”:
SLAC E158 (QeW ): SM running verified at ~ 6 level
future:
“u-quark dominated” : Qweak (QpW): projected to test SM running at ~ 10 level
“pure lepton”:12 GeV e2ePV (QeW ): projected to test SM running at ~ 25  level
June 24, 2005
DIS Parity
P. A. Souder
Comparing Qwe and QWp
QWP = 0.0716
 0.0029
QWe = 0.0449
 0.0040
Experiment
SUSY Loops


E6 Z/ boson
RPV SUSY
JLab at 12 GeV
will do a factor
of about 5 better!
Leptoquarks
SM
June 24, 2005
SM
DIS Parity
Erler,
P. A. Souder
Kurylov, R-M
The Qweak Experiment
June 24, 2005
DIS Parity
P. A. Souder
New Physics Reach
JLab Møller
LHC
Lee ~ 25 TeV
New Contact Interactions
Complementary; 1-2 TeV reach
LEP200
Lee ~ 15 TeV
Kurylov, Ramsey-Musolf, Su
Does Supersymmetry (SUSY) provide a
candidate for dark matter?
•Lightest SUSY particle (neutralino)
is stable if baryon (B) and lepton (L)
numbers are conserved
95% C.L.
JLab 12 GeV
Møller
•However, B and L need not be
conserved in SUSY, leading to
neutralino decay (RPV)
June 24, 2005
DIS Parity
P. A. Souder
Relative Shifts in Proton and Electron Weak Charges
due to SUSY Effects
June 24, 2005
DIS Parity
P. A. Souder
d/u at High x
Deuteron analysis has nuclear
corrections
APV for the
proton has no such
corrections
Must simultaneously
constrain higher twist effects
The challenge is to get statistical and systematic errors ~ 2%
June 24, 2005
DIS Parity
P. A. Souder
EMC Effect ?
A(Fe)/A( 2 H)
Ratio of Asymmetries
50 days running.
15 cm LD2 & 0.17 mm Fe Targets
(Iron to Deuterium)
x Bjorken
June 24, 2005
DIS Parity
P. A. Souder
A Concept for PV DIS Studies
•CW 100 µA at 11 GeV
•20 to 40 cm LH2 and LD2 targets
•Luminosity > 1038/cm2/s
• Magnetic spectrometer
would be too expensive
• Calorimeter to identify
electron clusters and reject
hadrons a la A4 at Mainz
• Toroidal sweeping field to
reduce neutrals, low energy
Mollers and pions
• Cherenkov detectors for pion
rejection might be needed
•solid angle > 200 msr
•Count at 100 kHz
• pion rejection of 102 to 103
June 24, 2005
DIS Parity
P. A. Souder
APV Measurements
APV ~ 105  Q2 to

104  Q2

E-05-007
June 24, 2005
0.1 to 100 ppm
DIS Parity
• Steady progress in technology
• part per billion systematic control
• 1% normalization control
•JLab now takes the lead
-New results from HAPPEX
-Photocathodes
-Polarimetry
-Targets
-Diagnostics
-Counting Electronics
P. A. Souder
EMC Effect ?
12
2
A( C)/A( H)
Ratio of Asymmetries
50 days running.
15 cm LD2 & 1% RL C12 Targets
(Carbon to Deuterium)
x Bjorken
June 24, 2005
DIS Parity
P. A. Souder
Parity Violation at Jlab
• Electron Beam Quality
– Simple laser transport system; pioneers in PV experiments with high
polarization cathodes (HAPPEX-I)
– CW beam alleviates many higher order effects; especially in energy
fluctuations
– HAPPEX-II preliminary result: Araw correction ~ 60 ppb
• High Luminosity
– High beam current AND high polarization
– Dense cryogenic targets with small density fluctuations
• Progression of Precision Experiments
– Facilitates steady improvements in technology
– Strong collaboration between accelerator and physics divisions
(APV) 1 part per billion
June 24, 2005
DIS Parity
(APV)/APV 1%
P. A. Souder