Transcript Weak Interactions & Hadrons

Electroweak Hadron Physics
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Short History
• b decay:
- effective GF
- V-A current
• E122: Parity Violation in ed
DIS, first confirmation of
Electroweak SM (1978)
sin2qw = 0.224 + 0.020
•High precision Z-pole measurements + e- beam technology:
 weak interactions are a new perturbative probe of
hadronic matter
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Weak Interactions & Hadrons
•Test Electroweak Sector of Standard Model @ low E
•New probe of hadron structure
NC
CC
•Semi-Leptonic: e- scattering
•Pure hadronic: PV meson-hadron couplings
• n beams
• e- beam?
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
e- Neutral Current
e’-(k’)
e-(k)
Z0
q=k-k’
Q2<<MZ2
Mg ~ e2/Q2
MZ ~ g2/MZ2
e = g sinqw
 Can’t
access NC via a cross section measurement
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Parity
Violation
a
e-’
a
eZ0
<< 1
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Observables from e- NC
Only Vector/Axial interference contributes
a
a
e-
e-’
V
•Suppressed by 1 - 4sin2qW ~ 0
q
Z0
V coupling to the lepton:
A
•Axial form factor GA(Q2)
•Anapole moment
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Observables from e- NC
V coupling to the target dominates:
a
a
e-
e-’
A
q
Z0
V
• Weak charge: QW = f(Z,N, sin2qW)
 Low E tests of SM
• QW(Q2)
Weak FF (See K. Paschke’s talk)
• Complementary probe (accuracy, kine.)
 Rn (elastic e-Pb), u/d (PVDIS), …
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Running of sin2qW
•sin2qW parametrizes all vector weak couplings
•Loop corrections: sin2qW  sin2qW(Q2)
3 types of measurements
at Q2<<MZ2:
•E158: Parity violation
in e--e- scattering
•Atomic parity violation
3%
•NuTeV: neutrino
NC/CC cross sections
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
SLAC Experiment E158
Detector
a
a
e
50 GeV
APV
=
21 September, 2005
Liquid
Hydrogen
s -s
s +s
PV
At tree level: A =
In practice:
e-escattering
m E GF
2p 
16 sin q2
(
(3 + cos2 q)2
APV ~ 1.5 x 10-7
David LHUILLIER – CEA Saclay
1
4
- sin2qw )
Small but very sensitive
EINN05, Milos
Experimental Challenges
oStatistics
• integrated rate = 4 GHz
• 1016 e- detected
• DA = 10-8
oBackground
•
•
•
•
e-p elastic
p production
radiative inelastic e-p
2 g and AT
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Experimental Challenges
oBeam monitoring
& resolution
jitter versus
statistics
storoid  30 ppm
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Experimental Challenges
oBeam systematics
Slow reversals
 false asymmetries
Polarized
Source
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
E158 Results
Phys.Rev.Lett.95:081601,2005
APV(Q2=0.026 GeV2) = -131  14stat  10syst ppb
sin2qW|exp = 0.2397 ± 0.0010 ± 0.0008
sin2θW|theo = 0.2381 ± 0.0006
Limits on physics beyond SM (95% CL):
• LLL ~ 10 TeV
• SO(10) Z’ ~ 900 GeV
• lepton flavor violating coupling
~ 0.01GF
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Running of sin2qW
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
NuTeV
Iron target
n
n
Z
21 September, 2005
David LHUILLIER – CEA Saclay
m
n
W
EINN05, Milos
NuTeV
n-hadron neutral current:
- hadron
LnNC
-

GF
n g m 1 - g 5 n   Lq q g m 1 - g 5 q   Rq q g m 1  g 5 q
2
Paschos - Wolfenstein Relation
s nNC - s nNC
2 1
2
2
2
R  n


sin
q

g
g
W
L
R
2
n
s CC - s CC

21 September, 2005

David LHUILLIER – CEA Saclay
g
2
L,R

  Lu, R   Ld, R
2
2

EINN05, Milos
NuTev Results
Phys. Rev. Lett. 88, 091802 (2002)
sin2qW|exp = 0.2360 ± 0.0013stat ± 0.0009syst
sin2θW|theo = 0.2309 ± 0.0004
3s discrepancy !
 New physics or spurious nuclear effect?
•NLO Corrections
•QCD symmetry violations (isospin, sea quarks)
•…
Sensitivity to many nuclear effects… but no obvious explanation so far
Need more experimental constraints
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Atomic PV
Semi-leptonic sector:
e - hadron
NC
L



GF
5
5




C
e
g
g
e
q
g
q

C
e
g
e
q
g
g
q

1q
m
m
2q
m
m
2 q

Radiative transition in the weak field of the nucleus (q ~ 1 MeV)
APV = x . QW
Atomic
Weak
structure
charge
QW = (2Z+N)C1u+(2N+Z)C1d
= Z(1-4sin2qW)-N ~ -N
g
Less sensitive but sub-percent accuracy !
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Atomic PV
• Z3 law  Heavy Atoms
• Control of the atomic structure x
 Cesium, chain of isotopes
• Highly suppressed QED transition
~
 |ns1/2> =|ns1/2>+|np1/2>
<ns1/2|D|n’s1/2> = E1 + M1 + E1PV + E1Stark
~
Forbiden

21 September, 2005
Suppressed
Induced by external E0 field
APV ~ E1PV / E1Stark
David LHUILLIER – CEA Saclay
Rate  E02
APV  1/E0
EINN05, Milos
133Cs
F=4
7s1/2
Boulder Experiment
m=+4
m=-4
D1,D2
m=-3
F=3
m=+3
6p3/2
D3
F=4
6s1/2
+ 6p1/2
F=3
F=5
4
3
2
Laser
D3
m=+4
D1
m=-4
m=-3
m=+3
21 September, 2005
D2
Signal= flux on photodiode
 QW(exp) = -72.71 ± 0.29(exp) ± 0.39(theo)
QW(theo) = -73.19 ± 0.13
David LHUILLIER – CEA Saclay
1s agreement
EINN05, Milos
Boulder Experiment
First measurement of a non-zero nuclear anapole moment
rhf=
APV(6s7s, DF=-1)
APV(6s7s,
DF=+1)
- 1 = (4.8 ± 0.7) 10-2
e-
(7 s !)
e-
g
p
Z0
p
p
• Similar e-/vector-nucleon/axial coupling but 5 times bigger
• Parity violation through internal meson exchange,
also measured in PV hadron scattering
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Running of sin2qW
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Future
Complementary targets
Moller
Ultra high precision
Atomic PV
(radioactive atoms,
isotopes…)
21 September, 2005
David LHUILLIER – CEA Saclay
Qpweak
EINN05, Milos
Qweak
Elastic ep
APV
Q 0
q0


 - GF  2 p
4
2



Q
Q
Q
B
Q
weak
 p

4
2
containsGEg ,M and GEZ,M
Constrained by other PV measurements at higher Q2
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Qweak
Kinematics:
Int. Rate = 6.4 GHz
<Q²> = 0.030 GeV2
<APV> = –0.29 ppm
Scattered e-
PV in elastic eElastically
p 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
SilicaSilica
(quartz)
Eight
Fused
(quartz)
Cerenkov Detectors
Region I Drift Chambers
GEM Detectors
Region 1
Beam:
E = 1.165 GeV
I = 180 μA
Pe = 85%
Čerenkov Detectors
GEM Detectors
Collimator With Eight Openings
Collimator with
q =89openings
± 2°
θ= 8° ± 2°
35 cm Liquid Hydrogen Target
Polarized
Electron
Beam
35cm
Liquid
Hydrogen Target
21 September, 2005
David LHUILLIER – CEA Saclay
DAPV/APV=2.2%
DQpW/QpW=4%
Dsin2qW=0.0007
EINN05, Milos
Running of sin2qW
Qweak
LC e-e-
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Future
a
e-’
a
e-
Complementary targets
Z0
Ultra high precision
•Strange FF, Neutron skin
•PVDIS
a
New hadron probe
p,d,4He,208Pb
e-’
a
eZ0
p,d
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Neutron Skin
a
a
a
a
e-
g
Z0
208Pb
Born Approximation
FW (Q2)
Fg (Q2)
-N Fn(Q2) + (1-4sin2qW) Z Fp(Q2)
Z Fp(Q2)
(DR2=R2n-R2p)
dRn/Rn~1%
21 September, 2005
David LHUILLIER – CEA Saclay
See R. Michaels’ poster
EINN05, Milos
Parity Violating DIS
a
e-’
a
eZ0
p,d
2
APV
GF Q

a(x)  f (y)b(x)
2p
a ( x) 

C1qQq f q ( x)
2
q q
Q f ( x)
b( x) 
C2qQq f q ( x)
Qq2 f q ( x)

fq(x): quark distribution functions
Judicious choices of kinematics and targets allow to test:
• Valence Quark distributions at high x
• C2q’s factors
• Higher twist physics & Charge symmetry breaking
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
PVDIS on 2H
Isoscalar target, most of quark distribution effects cancel out
•TeV scale physics
•Sensitivity to C2q
•Higher twist
•Isospin violation
21 September, 2005
Jlab 6GeV + 12GeV upgrade
David LHUILLIER – CEA Saclay
EINN05, Milos
Running of sin2qW
Qweak
DIS
12 GeV
LC e-e-
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos

PVDIS on 1H
APV
GF Q2

a(x)  f (y)b(x)
2p
u(x)  0.91d(x)
a(x) 
u(x)  0.25d(x)

Allows d/u measurement
on a single nucleon!
d/u @ x1
•SU(6): 1/2
•pQCD: 1/5
•SU(6) breaking: 0
Complementary to other approaches planned for the 12 GeV upgrade of Jlab:
•3H and 3He structure function ratio
•Deuteron structure functions with tagged slow recoiling neutrons
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
High x Measurement
• Multiple APV measurements (Q2, x) with multiple
targets
• Scattered electrons from 3 to 8 GeV
• “Huge” asymmetries
• Need large solid angle calorimeter
• “A4-like” , rates up to a few MHz
• Toroidal sweeping magnet to reject Low E pions
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Hadrons Weak Interactions
Ν2΄
Ν1΄
hw
hw ~ 10-7
Ν1
(π, ρ, ω)
~ 1 fm
Z scale ~ 0.001 fm
gs
proton,
neutron
gs ~ 1
Ν2
Repulsive hard core of strong NN interaction
 Meson exchange framework
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Weak Coupling Constants
fπ , hρ0, hρ1 , hρ2 , hω0 , hω1 , hρ1’
Longitudunal Asym in Elastic p + p ( 15, 45, 221, … MeV )
AL = 1±4 x 10-7 , Phys. Rev. Lett. 33, 1307, (1974) !!
First non-zero PV in NN-system: AL=2.3±0.9 x 10-7
Multiple energies: separation { hρ, hw }
Parity Mixed Doublets of Light Nuclei (18F,
Determination: { fπ }
19F, 21Ne
…)
PNC at Atomic Level – Anapole Moments (133Cs)
Determination: { fπ , hρ0}
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
LANSCE @ LANL
Goal:
Aexp= - 5±0.5 x 10-8
n + p
d + g
Accurate measurement of h1p
Taking Data !
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
γ + d  p + n
E(γ) = 3 – 8 MeV
The 10 MeV CW-Linac at IASA, Athens
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Summary
Experimental Advances
• Polarized sources and beam optics
• High rate integrating (few GHz) and counting
(few MHz)detectors
• Cryogenic Targets
• Polarimetry
Strong Physics cases
• TeV scale physics complementary to colliders
• Nucleon Structure at high Q2 high x
• Strange Form Factors
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Cesium PV Versus Time
sin2qw
0.240
0.238
Standard Model
0.236
0.234
0.232
0.230
Bennett
Wieman
Wieman et al.
1997
1998
1999
Derevianko
Kozlov
Porsev
Tupitsyn
Dzuba
Flambaum
2000
2001
Kuchiev
Flambaum
Johnson
Bednyhakov
Soff
2002
2003
Modifications in the theoretical corrections to the
atomic structure
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos
Weak meson-N Coupling Constants
DDH:
Desplanques, Donoghue, Holstein
D:
Desplanques
DZ:
Dubovic & Zenkin
KM:
Kaiser & Meissner
FCDH:
Feldman, Crawford, Dubach, Holstein
21 September, 2005
David LHUILLIER – CEA Saclay
EINN05, Milos