parity violation in pvdis with solid · parity violation in pvdis with solid p. a. souder,...
TRANSCRIPT
April 13, 2010 PVDIS with SOlid 2
Outline
• Physics potential– Standard Model Test– Charge Symmetry Violation (CSV)– Higher Twist– d/u for the Proton
• New Solenoidal Spectrometer (SoLID)• Polarimetry
April 13, 2010 PVDIS with SOlid 3
PV Asymmetries: Any Targetand Any Scattering Angle
(gAegV
T +β gVegA
T)
Forward Backward
•The couplings gT depend on electroweak physics as well as on the weak vector and axial-vector hadronic current •For PVDIS, both new physics at high energy scales as well as interesting features of hadronic structure come into play•A program with a broad kinematic range can untangle the physics
April 13, 2010 PVDIS with SOlid 4
PVDIS: Electron-Quark Scattering
Consider f1 f 1 → f2 f 2 f1 f2 → f1 f2or gij’s for all f1f2combinations and L,R combinations
Many new physics models give rise to neutral ‘contact’ (4-Fermi) interactions:Heavy Z’s, compositeness, extra dimensions…
C1u and C1d will be determined to high precision by Qweak, APV Cs
C2u and C2d are small and poorly known: one combination can be accessed in PV DIS
A
V
V
A
Moller PV is insensitive to the Cij
April 13, 2010 PVDIS with SOlid 5
Deep Inelastic Scattering
b(x) =C2i Qi fi
− (x)i
∑Qi2 fi
+ (x)i
∑
a(x) and b(x) contain quark
distribution functions fi(x)
APV =GFQ2
2παa(x) + Y (y)b(x)[ ]e-
N X
e-
Z* γ*
x ≡ xBjorken
a(x) =C1i Qi fi
+(x)i
∑Qi
2 fi+(x)
i∑
iii fff ±≡±
y ≡1− ′ E /E
New combination of: Vector quark couplings C1qAlso axial quark couplings C2q
b(x) =310(2C2u − C2d )
uv + dvu+ + d+
+L
At high x, APV becomes independent of x, W, with well-defined SM prediction for Q2 and y
Sensitive to new physics at the TeV scale
a(x) =310(2C1u − C1d ) 1+
2s+
u+ + d+
6.0
0
1
at high x
PVDIS: Only way to measure C2qUnknown radiative correctionsfor coherent processes
For an isoscalar target like 2H, structure functions largely cancel in the ratio at high x
April 13, 2010 PVDIS with SOlid 6
Sensitivity: C1 and C2 Plots
Cs
PVDIS
Qweak PVDIS
World’s data6 GeV
Precision Data
April 13, 2010 PVDIS with SOlid 7
Selected Electroweak Data
Evidence forunexpected
hadronic physics?
1. s≠s2. Nucleon CSV3. Nuclear CSV
_
April 13, 2010 PVDIS with SOlid 8
Search for CSV in PV DISδu(x) = up (x) − dn (x)δd(x) = d p (x) − un (x)
•u-d mass difference•electromagnetic effects
up (x) = dn (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
dudu
AA
PV
PV
+−
=δδδ 28.0For APV in electron-2H DIS:
Sensitivity will be further enhanced if u+d fallsoff more rapidly than δu-δd as x → 1
April 13, 2010 PVDIS with SOlid 9
Sensitivity with PVDIS
RCSV =δ APV x( )APV x( )
= 0.28δu x( )− δd x( )
u x( )+ d x( )
April 13, 2010 PVDIS with SOlid 10
Higher TwistSubject 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
April 13, 2010 PVDIS with SOlid 11
Why HT in PVDIS is SpecialStart with Lorentz InvarianceBjorken,
PRD 18, 3239 (78)
∫∫
⋅
⋅+∝
4
4
|)0()(|
|)0()()0()(|
deDjxjDl
xdeDjxJJxjDlA
xiq
xiq
νµµν
νµνµµν
Wolfenstein,NPB146, 477 (78)
( ) ( )dduuSdduuV µµµµµµ γγγγ +=⇔−= xdeDVxVDlVV xiq 4|)0()(|∫ ⋅= νµµν
SSVV
SSCCVVCCA
dudu
31
)(31)( 1111
+
++−= Zero in QPM
Next use CVC (deuteron only)
xdeddxuxuDlSVSVSSVV xiq 4)0()0()()(|))(( ⋅∫∝+−=− νµµν γγ
Higher-Twist valancequark-quark correlations
HT in F2 is dominated by quark-gluon correlations
Vector-hadronic piece only
April 13, 2010 PVDIS with SOlid 12
Parton Modelor
leading twist
Di-quarks
Quark-gluondiagram
What is a truequark-gluonoperator?
Quark-gluon operatorscorrespond to
transverse momentum
QCD equationsof motion
u
u d
u
Might be computedon the lattice
PVDIS is the only known way
to isolatequark-quarkcorrelations
Quark-Quark vs Quark-Gluon
April 13, 2010 PVDIS with SOlid 13
Higher Twist Fit to ν Data
Analysis of Alekhin, Kulagin, and Petti
April 13, 2010 PVDIS with SOlid 14
Statistical Errors (%) vs KinematicsStrategy: sub-1% precision over broad kinematic range for sensitive Standard Model test and detailed study of hadronic structure contributions
4 months at 11 GeV
2 months at 6.6 GeV
Error bar σA/A (%)shown at center of binsin Q2, x
April 13, 2010 PVDIS with SOlid 15
Coherent Program of PVDIS StudyStrategy: requires precise kinematics and broad range
+
−+= 2
23)1(11 x
QxAA CSVHT ββ
C(x)=βHT/(1-x)3
Fit data to:
• 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
yesnoyesHigher Twist
nonoyesCSVnoyesnoNew PhysicsQ2yx
April 13, 2010 PVDIS with SOlid 16
PVDIS on the Proton: d/u at High x
3-month run
)(25.0)()(91.0)()(
xdxuxdxuxaP
++
≈
Deuteron analysis has largenuclear corrections (Yellow)
APV for the proton has no such corrections
(complementary to BONUS)
The challenge is to get statistical and systematic errors ~ 2%
April 13, 2010 PVDIS with SOlid 17
CSV in Heavy Nuclei: EMC Effect
Additional possible
application of SoLID
Isovector-vector meanfield. (Cloet,
Bentz,and Thomas)
5%
April 13, 2010 PVDIS with SOlid 18
SoLID SpectrometerShashlyk
Calorimeter
ANL design
Babar Solenoid
International Collaborators:China (Gem’s)Italy (Gem’s)Germany (Moller pol.)
Gas Cerenkov
Baffles
GEM’s
JLab/UVA prototype
April 13, 2010 PVDIS with SOlid 19
Atomic Hydrogen For Moller Target
n +
n−
= e −2µB / kT ≈ 10 −14
• Tiny error on polarization
• Thin target (sufficient rates but no dead time)
• 100% electron polarization
• Non-invasive
• High beam currents allowed
• No Levchuk effect
10 cm, ρ = 3x1015/cm3
in B = 7 T at T=300 mK
Moller polarimetry from polarized atomic hydrogen gas, stored in an ultra-coldmagnetic trap
E. Chudakov and V. Luppov, IEEE Transactions on Nuclear Science, v 51, n 4, Aug. 2004, 1533-40
Brute force polarization
April 13, 2010 PVDIS with SOlid 20
High Precision ComptonAt high energies, SLD achieved 0.5%.Why do we think we can do better?
•SLD polarimeter near interaction region - background heavy•No photon calorimeter for production
•Hall A has “counting” mode (CW)•Efficiency studies•Tagged photon beam
• Greater electron detector resolution
So why haven’t we done better before?
Design (4.5GeV)
PREXH-III
PV-DIS
11 GeV
Distance from primary beam [mm]
Asy
mm
etry
•Small asymmetries = long time to precision = cross-checks are difficult
•Zero-crossing technique is new. (zero crossing gets hard near the beam)
•Photon calorimetry is harder at small Eγ
Its a major effort, but there is no obvious fundamental show-
stopper
April 13, 2010 PVDIS with SOlid 21
Error Budget in %
0.6Total
0.3Radiative Corrections
0.2Q2
0.4Polarimetry
0.3Statistics
April 13, 2010 PVDIS with SOlid 22
P. Bosted, J. P. Chen, E. Chudakov, A. Deur,
O. Hansen, C. W. de Jager, D. Gaskell, J. Gomez,
D. Higinbotham, J. LeRose,R. Michaels, S. Nanda, A. Saha, V. Sulkosky,
B. WojtsekhowskiJefferson Lab
P. A. Souder, R. Holmes Syracuse University
K. Kumar, D. McNulty, L. Mercado, R. MiskimenU. Massachusetts
H. Baghdasaryan, G. D. Cates,D. Crabb, M. Dalton, D. Day,N. Kalantarians, N. Liyanage,
V. V. Nelyubin, B. Norum, K. Paschke, S. Riordan,
O. A. Rondon, M. Shabestari,J. Singh, A. Tobias, K. Wang,
X. ZhengUniversity of Virginia
J. Arrington, K. Hafidi, P. E. Reimer, P. Solvignon
ArgonneD. Armstrong, T. Averett,
J. M. FinnWilliam and Mary
P. DecowskiSmith College
L. El Fassi, R. Gilman, R. Ransome, E. Schulte
RutgersW. Chen, H. Gao, X. Qian,
Y. Qiang, Q. YeDuke University
K. A. AniolCalifornia State
G. M. UrciuoliINFN, Sezione di
RomaA. Lukhanin, Z. E. Meziani,
B. SawatzkyTemple University
P. M. King, J. RocheOhio University
E. BeiseUniversity of Maryland
W. Bertozzi, S. Gilad, W. Deconinck, S. Kowalski,
B. MoffitMIT
Benmokhtar, G. Franklin, B. Quinn
Carnegie MellonG. Ron
Tel Aviv UniversityT. Holmstrom
Longwood University
P. MarkowitzFlorida International
X. JiangLos Alamos
W. KorschUniversity of Kentucky
J. ErlerUniversidad Autonoma
de MexicoM. J. Ramsey-Musolf
University of WisconsinC. Keppel
Hampton UniversityH. Lu, X. Yan, Y. Ye, P. ZhuUniversity of Science and Technology of
ChinaN. Morgan, M. PittVirginia Tech
J.-C. PengUniversity of Illinois
H. P. Cheng, R. C. Liu, H. J. Lu, Y. Shi
Huangshan UniversityS. Choi, Ho. Kang, Hy. Kang B.
Lee, Y. OhSeoul National
University J. Dunne, D. Dutta
Mississippi State
K. Grimm, K. Johnston, N. Simicevic, S. WellsLouisiana Tech
O. Glamazdin, R. PomatsalyukNSC Kharkov Institute
for Physics and Technology
Z. G. XiaoTsinghua University
B.-Q. Ma, Y. J. MaoBeijing University
X. M. Li, J. Luan, S. ZhouChina Institute of Atomic Energy
B. T. Hu, Y. W. Zhang, Y. Zhang
Lanzhou UniversityC. M. Camacho, E. Fuchey,
C. Hyde, F. ItardLPC Clermont,
Université BlaisePascal
A. DeshpandeSUNY Stony Brook
A. T. Katramatou, G. G. Petratos
Kent State UniversityJ. W. Martin
University of Winnipeg
PVDIS Collaboration
April 13, 2010 PVDIS with SOlid 23
Summary
• The physics is varied and exciting.– Excellent sensitivity to C2u and C2d.– Test CSV at quark level.– Unique window on higher twists.
• We will build a novel apparatus (with many other possible applications, eg. SIDIS)
April 13, 2010 PVDIS with SOlid 24
Layout ofSpectrometer using CDF coil
• Coil mounting is well understood from CDF–Designed to be
supported by end–Supports allow
radial movement in both ends for thermal
–One end fixed axially
• Will need to check for decentering forces due to field asymmetry (Lorentz forces)
April 13, 2010 PVDIS with SOlid 25
Error Projections for MollerPolarimetry
Table from MOLLER director’s review by E. Chudakov
April 13, 2010 PVDIS with SOlid 31
Need Full Phenomenology
T
LRRFFσσγγ =→+= )1(21
γγσ21
2
)2
1(22 FE
xyMyy
xyFdxdyd
EM
−−+∝
}])2
1(22{[22 21
2ZZ
A
V
Z
FE
xyMyy
xyFgGdxdyd γγ
γ πασ
−−+−∝
])2([22 3
2Z
V
A
Z
FyxgGdxdyd γ
γ πασ
−−∝
There are 5relevant structure
functions
EM
VZxa
σσγ=)(
BIGEM
AZxbyf
σσγ=)()(
EM
AZ
VZPV
BAσ
σσ γγ +=
Small; use ν data(Higher twist workshopat Madison, Wisconsin)
April 13, 2010 PVDIS with SOlid 33
Access to the Detectors• End Cap rolls
backward along the beam line on Hilman Rollers
• 342 metric tons for both end caps with baffles installed
• Must allow for 5% rolling resistance