1. PVDIS
June 2, 2011
PVDIS overview

2. Outline Review of Physics and how to optimize spectrometer
Summary of Progress
Open Issues
June 2, 2011
PVDIS overview

3. PVDIS: Electron-Quark Scattering
Moller PV is insensitive to the Cij
PV elastic e-p scattering, APV
C1u and C1d will be determined to high precision by Qweak, APV Cs
PV deep inelastic scattering
C2u and C2d are small and poorly known:
one combination can be accessed in PV DIS
New physics such as compositeness, leptoquarks:
Deviations to C2u and C2d might be fractionally large
June 2, 2011
PVDIS overview

4. Deep Inelastic Scattering
a(x) and b(x) contain quark distribution functions fi(x) e- N X Z* * 1
at high x
For an isoscalar target like 2H, structure functions largely cancel in the ratio at high x
At high x, APV becomes independent of x, W, with well-defined SM prediction for Q2 and y
New combination of:
Vector quark couplings C1q
Also axial quark couplings C2q
Sensitive to new physics at the TeV scale
Unknown radiative corrections
for coherent processes
PVDIS: Only way to measure C2q
June 2, 2011
PVDIS overview 4

5. Search for CSV in PV DIS For APV in electron-2H DIS: Strategy:
u-d mass difference
electromagnetic effects
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:
Sensitivity will be further enhanced if u+d falls off more rapidly than u-d as x  1
measure or constrain higher twist effects at x ~
precision measurement of APV at x → 0.8 to search for CSV
Strategy:
June 2, 2011
PVDIS overview

6. Subject of a workshop at Madison, Wisconsin
Higher Twist
Subject of a workshop at Madison, Wisconsin 
APV sensitive to diquarks: ratio of weak to electromagnetic charge depends on amount of coherence (elastic He vs PVDIS)
Do diquarks have twice the x of single quarks?
If Spin 0 diquarks dominate, likely only 1/Q4 effects
June 2, 2011
PVDIS overview

7. Need Full Phenomenology
Start with Lorentz Invariance
There are 5
relevant structure
functions
BIG
Small; use ν data
(Higher twist workshop
at Madison, Wisconsin)
June 2, 2011
PVDIS overview

8. Why HT in PVDIS is Special
Bjorken,
PRD 18, 3239 (78)
Start with CVC (deuteron only)
Wolfenstein,
NPB146, 477 (78)
Zero in QPM
Isospin decomposition
before using PDF’s
HT in F2 may be dominated
by quark-gluon correlations
Higher-Twist valance
quark-quark correlations
Vector-hadronic piece only
June 2, 2011
PVDIS overview

9. Quark-Quark vs Quark-Gluon
What is a true
quark-gluon
operator?
Parton Model or
leading twist
Quark-gluon
diagram u u u d
Quark-gluon operators
correspond to
transverse momentum
QCD equations
of motion
Di-quarks
Might be computed
on the lattice
June 2, 2011
PVDIS overview

10. OOPS: Higher Twist in b(x) is now Background
Talks by Mantry and Owens on this
subject are scheduled for PAVI11
These hadronic corrections can be
obtained from charged-current
neutrino scattering data
June 2, 2011
PVDIS overview

11. Statistical Errors (%) vs Kinematics
Strategy: sub-1% precision over broad kinematic range for sensitive
Standard Model test and detailed study of hadronic structure contributions
Error bar σA/A (%)
shown at center of bins
in Q2, x
4 months at 11 GeV
2 months at 6.6 GeV
June 2, 2011
PVDIS overview

12. Coherent Program of PVDIS Study
Strategy: requires precise kinematics and broad range
Fit data to:
C(x)=βHT/(1-x)3
Measure AD in NARROW bins of x, Q2 with 0.5% precision
Cover broad Q2 range for x in [0.3,0.6] to constrain HT
Search for CSV with x dependence of AD at high x
Use x>0.4, high Q2, and to measure a combination of the Ciq’s x y Q2
New Physics no
yes
CSV
Higher Twist
Errors on fit used
to optimize
spectrometer.
June 2, 2011
PVDIS overview

13. Sensitivity with PVDIS
June 2, 2011
PVDIS overview

14. Sensitivity: C1 and C2 Plots
6 GeV
World’s data
PVDIS
Precision Data
PVDIS
Qweak Cs
June 2, 2011
PVDIS overview

15. PVDIS on the Proton: d/u at High x
Independent FOM
Deuteron analysis has large
nuclear corrections (Yellow)
APV for the proton has no such corrections
(complementary to BONUS)
3-month run
The challenge is to get statistical and systematic errors ~ 2%
June 2, 2011
PVDIS overview

16. Which Magnet? Criteria are:
Acceptance (for 30 sectors)
Resolution (Probably non-issue)
Length of Cerenkov detectors—big issue?
June 2, 2011
PVDIS overview

17. Possible Magnets BaBar CDF CLEO Zeus Hall D
For PVDIS, we haven’t ruled
out any of these magnets.
(Need 5 Monte Carlo’s)
June 2, 2011
PVDIS overview

18. Will determine number of
GEM Tracking
GEM wires not orthogonal.
GEM produces analog output that must be interpreted.
Plan to use code developed for SBB spectrometer.
Will determine number of
planes required.
June 2, 2011
PVDIS overview

19. MC Ready for New Issues Momentum calibration. Need MC
Accidentals and dead time. Trigger: 10 kHz/sector; 100x more pions.
Errors due to pion backgrounds (1% contamination?).
June 2, 2011
PVDIS overview

20. Higher-Twist fit to ν-Data
June 2, 2011
PVDIS overview

21. A New Design for Precision PV DIS Physics Over a Broad Kinematic Range
High Luminosity on LH2 & LD2
Better than 1% errors for small bins
x-range
W2 > 4 GeV2
Q2 range a factor of 2 for each x
(Except x~0.75)
Moderate running times
Solenoid (from BaBar, CDF or CLEOII )
contains low energy backgrounds (Moller, pions, etc)
trajectories measured after baffles
Fast tracking, particle ID, calorimetry, and pipeline electronics
Precision polarimetry (0.4%)
June 2, 2011
PVDIS overview