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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, RamseyMusolf, Paschke, Pitt, Zheng. P. A. Souder Syracuse University. Outline.
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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, RamseyMusolf,
Paschke, Pitt, Zheng
P. A.Souder
Syracuse University
DIS Parity P. A. Souder
DIS Parity P. A. Souder
Weak Neutral Current (WNC) Interactions at Q2 << MZ2
Longitudinally Polarized Electron Scattering off Unpolarized Fixed Targets
(gAegVT+gVegAT)
DIS Parity P. A. Souder
APV ~
to
0.1 to 100 ppm
E05007
DIS Parity P. A. Souder
e2e
The Standard Model
DIS Parity P. A. Souder
(it just wont break!)
Nuclear Physics Long Range Plan:
What is the new standard model?
Low Q2 offers unique and complementary probes of new physics
 Double beta decay..
 neutrinos, EDMs..
 Muon g2, beta decay..
Input
G0
Output
DIS Parity P. A. Souder
AreLeptonic and hadronic
Z couplings seem inconsistent?
Most experts see the
precision data as
remarkably consistent
Perhaps there are bigger deviations lurking elsewhere???
DIS Parity P. A. Souder
Logical to push to higher energies, away from the Z resonance
LEPII, Tevatron, LHC access scales greater than L ~ 10 TeV
Complementary:
Parity Violating vs Parity Conserving
Q2 << scale of EW symmetry breaking
DIS Parity P. A. Souder
Atomic Parity Violation (APV)
series of isotopes
APV on Cs
SemiLeptonic
PV Elastic electronproton scattering at JLab Qweak
PV Deep Inelastic Scattering at upgraded JLab
NuTeV
Unique, outstanding opportunity for a dedicated apparatus with JLab upgrade
e scattering in reactor
Leptonic
Møller scattering at upgraded JLab
E158
Best low energy measurement until Linear Collider or Factory
DIS Parity P. A. Souder
Figure of Merit rises linearly with Elab
SLAC E158
Jlab at 12 GeV
Purely leptonic reaction
Weak charge of the electron:
QWe ~ 1  4sin2W
Unprecedented opportunity: The best precision at Q2<<MZ2 with the least theoretical uncertainty until the advent of a linear collider or a neutrino factory
DIS Parity P. A. Souder
Present Results and Future Experiments
DIS Parity P. A. Souder
Qeweak : Electron Weak Charge – SLAC E158 Experiment
Parityviolating Moller scattering
Q2 ~ .026 GeV2
~ 4 – 7 mrad
E ~ 48 GeV
at SLAC End Station A
Final results: hepex/0504049
APV = 131 14 (stat) 10 (syst) ppb
sin2eff(Q2=0.026 GeV2) =0.2397 ± 0.0010 ±0.0008
Running of sin2eff established at 6 level in pure leptonic sector
DIS Parity P. A. Souder
4000 hours
(APV)=0.58 ppb
Toroidal spectrometer ring focus
APV = 40 ppb
E’: 36 GeV
lab = 0.53o0.92o
150 cm LH2 target
Ibeam = 90 µA
Mack, Reimer, at al
DIS Parity P. A. Souder
Does Supersymmetry (SUSY) provide a candidate for dark matter?
JLab Møller
ee ~ 25 TeV
New Contact Interactions
LEP200
Kurylov, RamseyMusolf, Su
ee ~ 15 TeV
DIS Parity P. A. Souder
Examples:
The Qweak Apparatus
(Calibration Mode Only  Production & Calibration Modes)
Quartz Cherenkov Bars
(insensitive to
nonrelativistic particles)
Region 2: Horizontal drift chamber location
Region 1: GEM
Gas Electron Multiplier
Minitorus
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
DIS Parity P. A. Souder
Qpweak & Qeweak – Complementary Diagnostics for New Physics
JLab Qweak
SLAC E158

(proposed)
Run I + II + III
(preliminary)
±0.006
DIS Parity P. A. Souder
Running coupling constants in QED and QCD
QCD(running of s)
QED (running of )
137
s
DIS Parity P. A. Souder
What about the running of sin2W?
QWe
modified
sin2W runs with Q2
(sin2W) ~ 0.0003
Comparable to single collider measurements
DIS Parity P. A. Souder
Parity Violation in Deep Inelastic Scattering
DIS Parity P. A. Souder
V
A
A
V
C1u and C1d will be determined to high precision by Qweak, Cs
C2u and C2d are small and poorly known:
one combination can be accessed in PV DIS
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 2C2uC2d by more than a factor of 20
DIS Parity P. A. Souder
e
e
*
Z*
X
N
fi(x) are quark distribution functions
For an isoscalar target like 2H, structure functions largely cancel in the ratio:
Provided Q2 >> 1 GeV2 and W2 >> 4 GeV2 and x ~ 0.2  0.4
Must measure APV to fractional accuracy better than 1%
DIS Parity P. A. Souder
1000 hours
(APV)=0.65 ppm
(2C2uC2d)=±0.0086±0.0080
PDG (2004): 0.08 ± 0.24
Theory: +0.0986
E’: 5.0 GeV ± 10%
lab = 12.5o
60 cm LD2 target
Ibeam = 90 µA
APV = 217 ppm
xBj ~ 0.235, Q2 ~ 2.6 GeV2, W2 ~ 9.5 GeV2
DIS Parity P. A. Souder
(2C2uC2d)=0.012
(sin2W)=0.0009
Unique, unmatched constraints on axialvector quark couplings:
Complementary to LHC direct searches
Examples:
DIS Parity P. A. Souder
Why should we believe DISparitywhen no one Believes NuTeV?
DIS Parity P. A. Souder
Paschos & Wolfenstein ( PR D7, 91 (73)):
PW ratio minimizes sensitivity to PDFs, higherorder corrections
Result is off by 2.8 σ
DIS Parity P. A. Souder
Features very large kinematic acceptance
μ
Charged current
Neutral current
DIS Parity P. A. Souder
PW Ratio depends on the following assumptions:
JLab 12 GeV
issues
Nobody believes
that this is the
problem
DIS Parity P. A. Souder
DIS Parity P. A. Souder
For APV in electron2H DIS:
Strategy:
Sensitivity will be further enhanced if u+d falls off more rapidly than ud as x 1
DIS Parity P. A. Souder
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
DIS Parity P. A. Souder
(Does not
Evolve)
DIS Parity P. A. Souder
F2(x,Q2)=F2(x)(1+D(x)/Q2)
Q2=(W2M2)/(1/x1)
Q2min=Q2(W=2)
If D(x)~C(x), Parity might show higher twist
At high x without needing QCD evolution.
DIS Parity P. A. Souder
+ small corrections
DIS Parity P. A. Souder
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%
DIS Parity P. A. Souder
DIS Parity P. A. Souder
Apparatus Needed for PVDIS
DIS Parity P. A. Souder
E05007: 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, “parityquality” 80% pol. beam;
25cm LD2 target;
Two HRS detect scattered electrons.
DIS Parity P. A. Souder
DIS Parity P. A. Souder
Need Large
θ for large
x and Q2
6 GeV
HMS and SHMS
are fine for
small θ
50% azimuthal coverage assumed
DIS Parity P. A. Souder
DIS Parity P. A. Souder
Cut on 0.6<y<0.8
DIS Parity P. A. Souder
JLab Upgrade
Need toroid to block γ’s and
low energy π’s
DIS Parity P. A. Souder
d/u Measurements for Proton
(Kent Paschke simulation)
A couple weeks of beam time with toroid spectrometer
DIS Parity P. A. Souder
Example: d/u of Proton
Compare MAD Spectr. to Toroid Spectr.
Curves from
Melnithouk
and Thomas
d/u
off shell
on shell
DIS Parity P. A. Souder
EMC effect in Parity Violation ?
Cross section data from J. Gomez et.al. PRD 49 (1994) 4348
DIS Parity P. A. Souder
DIS Parity P. A. Souder
DIS Parity P. A. Souder
Future Directions for PV Moller and APV
e2ePV: ParityViolating Moller scattering at 12 GeV JLAB
(Mack, Reimer, et al.)
Atomic Parity Violation Future Directions
Note: isotope ratios can eliminate large atomic structure theory uncertainties
DIS Parity P. A. Souder
Elastically Scattered Electron
Luminosity
Monitors
Region III
Drift Chambers
Toroidal Magnet
Region II
Drift Chambers
Region I
GEM Detectors
Eight Fused Silica (quartz)
Čerenkov Detectors
Collimator with 8 openings
θ= 8° ± 2°
35cm Liquid Hydrogen Target
Polarized Electron Beam
Overview of the QpWeak Experiment
Experiment Parameters
(integration mode)
Incident beam energy: 1.165 GeV
Beam Current: 180 μA
Beam Polarization: 85%
LH2 target power: 2.5 KW
Central scattering angle: 8.4° ± 3°
Phi Acceptance: 53% of 2p
Average Q²: 0.030 GeV2
Acceptance averaged asymmetry:–0.29 ppm
Integrated Rate (all sectors): 6.4 GHz
Integrated Rate (per detector): 800 MHz
DIS Parity P. A. Souder
“Running of sin2W” : Current Status and Future Prospects
12 GeV
QW(e)
present:
“dquark dominated” : Cesium APV (QAW): SM running verified at ~ 4 level
“pure lepton”: SLAC E158 (QeW ): SM running verified at ~ 6 level
future:
“uquark 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
DIS Parity P. A. Souder
QWP = 0.0716
QWe = 0.0449
Experiment
SUSY Loops
E6 Z/ boson
RPV SUSY
Leptoquarks
SM
SM
Comparing Qwe and QWp
JLab at 12 GeV
will do a factor
of about 5 better!
Erler, Kurylov, RM
DIS Parity P. A. Souder
DIS Parity P. A. Souder
LHC
Complementary; 12 TeV reach
Does Supersymmetry (SUSY) provide a candidate for dark matter?
JLab Møller
ee ~ 25 TeV
New Contact Interactions
LEP200
ee ~ 15 TeV
Kurylov, RamseyMusolf, Su
95% C.L.
JLab 12 GeV
Møller
DIS Parity P. A. Souder
Examples:
Relative Shifts in Proton and Electron Weak Charges
due to SUSY Effects
DIS Parity P. A. Souder
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%
DIS Parity P. A. Souder
50 days running.
15 cm LD2 & 0.17 mm Fe Targets
A(Fe)/A( H)
2
Ratio of Asymmetries (Iron to Deuterium)
DIS Parity P. A. Souder
DIS Parity P. A. Souder
APV ~
to
0.1 to 100 ppm
E05007
DIS Parity P. A. Souder
50 days running.
15 cm LD2 & 1% RL C12 Targets
2
12
A( C)/A( H)
Ratio of Asymmetries (Carbon to Deuterium)
DIS Parity P. A. Souder
(APV)/APV 1%
(APV) 1 part per billion
DIS Parity P. A. Souder