![Page 1: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/1.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 1/64
C3q Measurement Using Polarized e+/e- Beams at
JLab
– Introduction — Standard Model of Electroweak Interaction
– Neutral Weak Coupling Constants
– C3q Measurements
– Summary
Xiaochao ZhengUniv. of VirginiaMarch 27, 2009
![Page 2: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/2.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 2/64
Four Interactions of Our Nature
Electron scattering has been widely used to study
Structure of the nucleon — strong interactions, pQCD;
(Recently) parity violation electron scattering:
strange-quark content of the nucleon (elastic)
Electroweak interactions (DIS)
Gravitational General relativity Well understood at large distances
Electro-Magnetic 1/137
Weak
Strong SU(3), QCD less understood, no analytical calculation
10-38
SU(2)L X U(1)
Y
EM, weak: almost fully understood,
but there is room for New Physics10-5
10-1~100
![Page 3: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/3.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 3/64
Electroweak Interaction – Charged Currents
1932, charged pion and muon decay indicate a fourth type of interaction:
−. −.
−. e−. e
Much longer than strong (10-23 s) or electromagnetic (10-16 s) decays
1932, based on QED, Fermi proposed:
=2.6×10−8 s
=2.2×10−6 s
M = e u p u
p −1
q2 −e ue u
e = −e2
q2 j
em p j em, e
M = G u n u
p u e
ue
1956, when Parity violation was first proposed (and test by experiments), the only modification needed is: 1−5
![Page 4: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/4.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 4/64
MCC =4G
2J J
.
If further assume that weak interaction occurs by exchanging a (W) particle, similar to the photon in electromagnetic interactions, then
M = g
2u
1
21− 5 u 1
MW
2 −q2 g
2ue
1
21−5ue
if q2<<MW
2 then G
2=
g2
8 MW
2
![Page 5: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/5.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 5/64
1973, with developement of beams, found:
e−. e−. N X N Xcannot be explained by CC;
magnitude of strength indicate Neutral Currents.
Electroweak Interaction – Neutral Currents
M NC =4 G
22 J
NC J NC ,
If further assume that weak interaction occurs by exchanging a (W) particle, similar to the photon in electromagnetic interactions, then
M = g
2u
1
21− 5 u 1
MW
2 −q2 g
2ue
1
21−5ue
J NC =
1
2 u 1
21−5u J
NC q = uq
1
2 c
V
q −cA
q 5uq
![Page 6: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/6.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 6/64
1961, construct a SU(2)L group using charged currents, quantum number:
Weak isospin T.
Linear combination of the two is a neutral current, but it couples only to Left-handed fermions,
while experimentally observed NC couples to both R- and L-handed,
On the other hand, EM [U(1)] also couple to both R- and L-H fermions.
Can combine NC from SU(2)L and UEM(1) to construct:
jem
J NC
⇔ J 3
j Y
completes SU(2)L
U(1)Y, Y: weak hyper
charge
Q = T 3Y
2
![Page 7: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/7.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 7/64
W 1
W 2
W 3
B
⇔
W .
W −.
A
Z
A = B cosW
W 3 sin
Wm=0
Z = −B sin W
W 3 cos
Wm≠0
![Page 8: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/8.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 8/64
SM works well at present energy range;
Conceptual reasons for new physics:
What happens in the “high-energy desert”?
ElectroWeak Standard Model
Data exist: cannot be explained by the SM ( m, NuTeV
anomaly...);
(250 GeV ~ 5 x 1014 GeV ~ 2.4 x 1018 GeV)?
![Page 9: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/9.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 9/64
Exploring Nucleon Structure Using Electron ScatteringElastic, quasi-elastic, resonances, deep inelastic
(Quasi-) elastic – the nucleus (nucleon) appears as a rigid body
Resonance region – quarks inside the nucleon react coherently
Deep Inelastic Scattering (DIS):
Quarks start to react incoherently (start to see constituents of the nucleon)
(Can test pQCD)
Q2=2MT N
![Page 10: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/10.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 10/64
Weak Interaction in DIS (Parity Violating DIS)
![Page 11: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/11.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 11/64
study hadron structure
elastic scattering: strange form factors A4(MAINZ), G0, HAPPEX (JLab), SAMPLE (MIT/Bates)
DIS: higher twist effects, charge symmetry violation... PVDIS
test the electroweak standard model E158(SLAC), Qweak(JLab)
Electromagnetic observables — , A...
Weak observables — parity violating asymmetries (APV)
(polarized beam + unpolarized target)
ALR
≡ r− l
r l≈
Q2
MZ
2≈120 ppm
at Q2=1GeV /c2
APV
= +
Parity Violating Electron Scattering
![Page 12: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/12.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 12/64
SM works well at present energy range;
Conceptual reasons for new physics:
What happens in the “high-energy desert”?
ElectroWeak Standard Model
Data exist: cannot be explained by the SM ( m, NuTeV
anomaly...);
(250 GeV ~ 5 x 1014 GeV ~ 2.4 x 1018 GeV)?
![Page 13: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/13.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 13/64
SM works well at present energy range;
Conceptual reasons for new physics:
What happens in the “high-energy desert”?
indirect searches:
E158, NuTeV, Qweak, PVDIS
High energy direct searches:
LEP, LHC
Search for Physics beyond the Standard Model
ElectroWeak Standard Model
(250 GeV ~ 5 x 1014 GeV ~ 2.4 x 1018 GeV)?
![Page 14: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/14.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 14/64
Testing the EW Standard Model – Running of sin2W and the NuTeV Anomaly
(expected)
![Page 15: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/15.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 15/64
Current Knowledge on Weak Coupling Coeffecients
Facility Process Result SM Value
SLAC 1.39 -0.7185
SLAC 1.39 -0.0983
CERN 34 1.4351
CERN 66 1.4204
MAINZ 0.20 -0.8544
Bates 0.0225 0.1528
Bates 0.1 -0.0624
Bates 0.04 -0.0624
0.03 approved -0.0357
0 -73.16
0 -116.8
Fit low 0.1528
All -0.5297
PVES -0.0095
Data -0.0621
Q2 Ciq Combination
e--D DIS 2C1u
-C1d -0.90± 0.17
e--D DIS 2C2u
-C2d 0.62± 0.81
m±-D DIS 0.66(2C2u-C2d)+2C3u
-C3d 1.80± 0.83
m±-D DIS 0.81(2C2u
-C2d
)+2C3u
-C3d 1.53± 0.45
e--Be QE 2.68C1u
-0.64C1d
+2.16C2u
-2C2d -0.94± 0.21
e--C elastic C1u
+C1d 0.138±0.034
e--D QE C2u
-C2d -0.042± 0.057
e--D QE C2u
-C2d -0.12± 0.074
JLab e--p elastic 2C1u
+C1d
133Cs APV -376C1u
-422C1d -72.69±0.48
205Tl APV -572C1u
-658C1d -116.6±3.7
e--A C1u
+C1d 0.1358±0.0326
C1u
-C1d -0.4659±0.0835
C2u
+C2d -0.2063±0.5659
C2u
-C2d -0.0762±0.0437
J. Erler, M.J. Ramsey-Musolf, Prog. Part. Nucl. Phys. 54, 351 (2005) R. Young, R. Carlini, A.W. Thomas, J. Roche, PRL 99, 122003 (2007) & priv.
comm.
new
PDG2002 (best): (2C2u-C2d)=±0.24
Som
e N
ew
Ph
ysi
cs c
an
aff
ect
C2
q,
bu
t n
ot
C1
q
C3q
=gA
e gA
qC1q
=gA
e gV
q C2q
=gV
e gA
q
![Page 16: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/16.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 16/64
Current Knowledge on C1,2q
MIT/ Bates
SLAC/Prescott
Qweak (expected)
R. Young (PVES)
R. Young (combined)
PDG best fit
Cs APV
PDG 2006 fitSAMPLE
SLAC/ Prescott
R. Young (combined)
all are 1 limit
Best: PDG2002 (2C2u-C2d) = 0.24
C2
u+C
2d
1.25
1.5
1.75
1.0
0.75
0.5
0.25
0
0.25
-0.5
-0.75
C2u-C2d
- 0.2 0.40.20- 0.4
0.10
0.125
0.15
0.175
C1u-C1d
- 0.4- 0.6- 0.8
C1
u+
C1
d
Tl APV
![Page 17: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/17.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 17/64
Neutral Weak Couplings in Electron DIS
APV
= +
LSM
PV =−G
F
2e e∑q
C2q q 5 q
axial electron * vector quark :
vector electron * axial quark :
LSM
PV=−G
F
2e 5 e ∑q
C1q q q
C2d
=gV
e gA
d =1
2−2 sin2
W
C2u
=gV
e gA
u =−1
22 sin 2
WC
1u=g
A
e gV
u =−1
2
4
3sin2
W
C1d
=gA
e gV
d =1
2−
2
3sin 2
W
12
q gVq −g A
q 5q
12
e g Ve −g A
e 5e
![Page 18: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/18.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 18/64
Deuterium:
PVDIS Asymmetries
Ad
= 540 ppmQ22 C
1u[1R
C x ]−C
1d[1R
S x ]Y 2 C
2u−C
2d R
V x
5RS x 4 R
C x
APV
= +
![Page 19: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/19.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 19/64
Deuterium:
PVDIS Asymmetries
APV
= +
Ad
= 540 ppmQ22 C
1u[1R
C x ]−C
1d[1R
S x ]Y 2 C
2u−C
2d R
V x
5RS x 4 R
C x
+
L=LSM
PV LNEW
PV
LSM
PV =−G
F
2e e∑q
C2q q 5 q L
NEW
PV =g2
4 2e e∑ f
hA
q q 5q
g: coupling constant, : mass limit, hAq: effective coefficient
New physics sensitivity:
![Page 20: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/20.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 20/64
Deuterium:
PVDIS Asymmetries
APV
= +
Ad
= 540 ppmQ22 C
1u[1R
C x ]−C
1d[1R
S x ]Y 2 C
2u−C
2d R
V x
5RS x 4 R
C x
+
L=LSM
PV LNEW
PV
LSM
PV =−G
F
2e e∑q
C2q q 5 q L
NEW
PV =g2
4 2e e∑ f
hA
q q 5q
g: coupling constant, : mass limit, hAq: effective coefficient
New physics sensitivity:
g≈ [8G
F∣ 2 C2u
−C 2d∣]−1/ 2
Sensitive to: Z' searches, compositeness, leptoquarks
Mass limit:
![Page 21: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/21.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 21/64
PV DIS and Other SM Test ExperimentsE158/Moller (SLAC)
NuTeV (FNAL)Atomic PV
PVDIS (JLab)Qweak (JLab)
2 (2C1u+C1d)
Coherent quarks in the proton
Purely leptonicWeak CC and NC differenceNuclear structure?Other hadronic effects?
Coherent Quarks in the Nucleus- 376C1u - 422C1d
Nuclear structure?
(2C1u-C1d)+Y(2C2u-C2d)
Isoscalar quark scattering
Cartoons borrowed from R. Arnold (UMass)
Different ExperimentsProbe Different
Parts of Lagrangian,
PVDIS is the only one accessing C2q
![Page 22: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/22.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 22/64
RSx =
2 [s x s x ]
u xu xd x d x
PVDIS Asymmetries
RCx =
2 [c xc x]
u xu x d x d x R
Vx =
uV xd
V x
u xu x d x d x
APV
= +
Deuterium:
Ad
= 540 ppmQ22 C
1u[1R
C x ]−C
1d[1R
S x ]Y 2 C
2u−C
2d R
V x
5RS x 4 R
C x
Also sensitive to:
quark-gluon correlations (higher-twist effects)
Charge symmetry violation
up x ≠dn x d px ≠un x
![Page 23: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/23.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 23/64
PVDIS asymmetry has the potential to explore New Physics, study hadronic effects/CSV ...... However, hasn't been done since 1978.
1970's, result from SLAC E122 consistent with sin2W=1/4,
established the Electroweak Standard Model;C.Y. Prescott, et al., Phys. Lett. B77, 347 (1978)
PVDIS Experiment – Past, Present and Future
![Page 24: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/24.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 24/64
PVDIS asymmetry has the potential to explore New Physics, study hadronic effects/CSV ...... However, hasn't been done since 1978.
(Re)start PVDIS at JLab 6 & 12 GeV
Difficulty: separate New Physics and hadronic effects
1970's, result from SLAC E122 consistent with sin2W=1/4,
established the Electroweak Standard Model;C.Y. Prescott, et al., Phys. Lett. B77, 347 (1978)
PVDIS Experiment – Past, Present and Future
![Page 25: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/25.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 25/64
PVDIS asymmetry has the potential to explore New Physics, study hadronic effects/CSV ...... However, hasn't been done since 1978.
Do a first measurement at JLab 6 GeV:
If observe a significant deviation from the SM value, it will definitely indicate something exciting;
Indicate either electroweak new physics, or current understanding of strong interation is worse than we thought.
1970's, result from SLAC E122 consistent with sin2W=1/4,
established the Electroweak Standard Model;C.Y. Prescott, et al., Phys. Lett. B77, 347 (1978)
PVDIS Experiment – Past, Present and Future
New electroweak Physics
Non-perturbative QCD (higher-twist) effects
Charge symmetry violation
Likely to be small, but need exp confirmation
Small from MRST fit (90% CL ~1%)
At the 6 GeV precision:
![Page 26: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/26.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 26/64
PVDIS asymmetry has the potential to explore New Physics, study hadronic effects/CSV ...... However, hasn't been done since 1978.
Do a first measurement at JLab 6 GeV:
If observe a significant deviation from the SM value, it will definitely indicate something exciting;
Indicate either electroweak new physics, or current understanding of strong interation is worse than we thought.
At 12 GeV, a larger, well-plannedwell-planned PVDIS program could separate all three: New Physics, HT, CSV, important information for both EW and Strong interaction study.
1970's, result from SLAC E122 consistent with sin2W=1/4,
established the Electroweak Standard Model;C.Y. Prescott, et al., Phys. Lett. B77, 347 (1978)
PVDIS Experiment – Past, Present and Future
![Page 27: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/27.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 27/64
JLab 6 GeV Experiment 08-011
Use 85mA, 6 GeV, 80% polarized beam on a 25-cm LD2 target;
Two Hall A High Resolution Spectrometers detect scattered electrons;
Measure PV asymmetry Ad at Q2=1.10 and 1.90 GeV2 to 2.7% (stat.);
Ad at Q2=1.10 will limit the higher twist effects;
If HT is small, can extract 2C2u-C2d from Ad at Q2=1.90 to ±0.04 (or
with reduced precision if higher twists are un-expectedly large)
Co-spokesperson & contact: X. ZhengCo-spokesperson: P.E. Reimer, R. Michaels
(Hall-A Collaboration Experiment, approved by PAC27, re-approved by PAC33 for 32 days, rated A-)
![Page 28: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/28.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 28/64
Current Knowledge on C1,2q
MIT/ Bates
SLAC/Prescott
Qweak (expected)
R. Young (PVES)
R. Young (combined)
PDG best fit
Cs APV
PDG 2006 fitSAMPLE
SLAC/ Prescott
R. Young (combined)
all are 1 limit
Best: (2C2u-C2d) = 0.24
C2
u+C
2d
1.25
1.5
1.75
1.0
0.75
0.5
0.25
0
0.25
-0.5
-0.75
C2u-C2d
- 0.2 0.40.20- 0.4
0.10
0.125
0.15
0.175
C1u-C1d
- 0.4- 0.6- 0.8
C1
u+
C1
d
Tl APV
![Page 29: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/29.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 29/64
C2q from JLab E08-011
MIT/ Bates
SLAC/Prescott
Qweak (expected)
R. Young (PVES)
R. Young (combined)
PDG best fit
Cs APV
PDG 2006 fitSAMPLE
SLAC/ Prescott
R. Young (combined)
all are 1 limit
Best: (2C2u-C2d) = 0.24 0.04 (factor of six improvement);
New physics mass limit:
C2
u+C
2d
1.25
1.5
1.75
1.0
0.75
0.5
0.25
0
0.25
-0.5
-0.75
C2u-C2d
- 0.2 0.40.20- 0.4
0.10
0.125
0.15
0.175
C1u-C1d
- 0.4- 0.6- 0.8
C1
u+
C1
d
Tl APV
JLab E08-011 (PDG
fit)
JLab E08-011 (R. Young's
fit)
g
≈ [8 GF∣ 2 C
2u−C
2d∣]
−1 /2≈ 0.9 TeV
![Page 30: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/30.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 30/64
Higher precision, possibly sensitive to 1) New Physics beyond the SM; 2) Charge Symmetry Violation (CSV)
Two approaches (conditionally approved):
Hall C “baseline” SHMS+HMS: PR12-07-102 (P.E. Reimer, X-C. Z, K. Paschke)
1% on Ad, extraction of C2q, sin2W (if higher-twist and CSV are
negligible);
PVDIS Program at JLab 12 GeV
Hall A large acceptance “solenoid” device: PR09-012
Measure Ad to 1% for a wide range of (x,Q2,y), clean separation of
New Physics (via C2q and sin2W), HT and CSV possible;
Extract d/u at large x from PVDIS on a proton target, free of nuclear effects;
Other hadronic physics study possible: A1n at large x, Semi-inclusive
DIS.
![Page 31: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/31.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 31/64
Hall A large acceptance “solenoid” device: PR09-012
Measure Ad to 1% for a wide range of (x,Q2,y), clean separation of
New Physics (via C2q and sin2W), HT and CSV possible;
Extract d/u at large x from PVDIS on a proton target, free of nuclear effects;
Other hadronic physics study possible: A1n at large x, Semi-inclusive
DIS.
Higher precision, possibly sensitive to 1) New Physics beyond the SM; 2) Charge Symmetry Violation (CSV)
Two approaches (conditionally approved):
Hall C “baseline” SHMS+HMS: PR12-07-102 (P.E. Reimer, X-C. Z, K. Paschke)
1% on Ad, extraction of C2q, sin2W (if higher-twist and CSV are
negligible);
PVDIS Program at JLab 12 GeV
![Page 32: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/32.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab 32/64
Hall A large acceptance “solenoid” device: PR09-012
Measure Ad to 1% for a wide range of (x,Q2,y), clean separation of
New Physics (via C2q and sin2W), HT and CSV possible;
Extract d/u at large x from PVDIS on a proton target, free of nuclear effects;
Other hadronic physics study possible: A1n at large x, Semi-inclusive
DIS.
Higher precision, possibly sensitive to 1) New Physics beyond the SM; 2) Charge Symmetry Violation (CSV)
Two approaches (conditionally approved):
Hall C “baseline” SHMS+HMS: PR12-07-102 (P.E. Reimer, X-C. Z, K. Paschke)
1% on Ad, extraction of C2q, sin2W (if higher-twist and CSV are
negligible);
PVDIS Program at JLab 12 GeV
![Page 33: Xiaochao Zheng, International Workshop on Positrons at JLab 1/64 C 3q Measurement Using Polarized e + /e - Beams at JLab – Introduction — Standard Model](https://reader030.vdocuments.mx/reader030/viewer/2022032703/56649f535503460f94c77c61/html5/thumbnails/33.jpg)
Xiaochao Zheng, International Workshop on Positrons at JLab
33/64
Measurement of neutron asymmetry A1n in the valence quark
region at JLab 12 GeV
Flagship experiment
Will be one of the first experiments to run (~2014?)
PVDIS at 12 GeV
Ultimate goal: clean separation of New Physics and CSV (2015 or later?)
Summary (2013 - )