low energy electroweak precision tests
DESCRIPTION
Low Energy Electroweak Precision Tests. Perspective Motivations Precision program WNC experiments Universality EDMs, g-2 FCNC. Motivations. WNC, Z, W established SU(2) X U(1) SM Z pole most precise (0.1%) and excluded many BSM scenarios - PowerPoint PPT PresentationTRANSCRIPT
P. Langacker ICHEP2004 (8/16/04)
Low Energy Electroweak Precision Tests
•Perspective–Motivations–Precision program
•WNC experiments•Universality•EDMs, g-2•FCNC
P. Langacker ICHEP2004 (8/16/04)
P. Langacker ICHEP2004 (8/16/04)
MotivationsMotivations• WNC, Z, W established SU(2) X U(1) SM• Z pole most precise (0.1%) and excluded
many BSM scenarios• However, Z pole is blind or less sensitive
to many types of new physics (Z’, SUSY loops, RPV, new operators, exotics, leptoquarks, LED)
• Running sin2 W (new physics)• Precision low energy WNC (few percent)
still important• FCNC, g-2, EDMs complementary to
WNC, Z pole and collider
P. Langacker ICHEP2004 (8/16/04)
A Heavy Z’?• Strings, GUTs, LED, DSB, Little Higgs (best motivated
after SUSY)• Solution to problem• Highly nonstandard Higgs (doublet-singlet mixing) and
neutralino sectors• Chiral exotics• Electroweak baryogenesis• Cold dark matter• Family nonuniversality: tree level contribution to rare
B decays
P. Langacker ICHEP2004 (8/16/04)
Weak Neutral Current below the Z-pole
• Z-pole insensitive to effects not directly involving Z• Loop effects from new physics: (/)(M/Mnew)2
(Shufang Su)– muon g-2: M=mmuon g-2: M=m , , new new 2x10 2x10-9-9, , expexp < 10 < 10-9 -9
-decay, -decay, -decay: M=m-decay: M=mWW , , new new 10 10-3-3, , expexp 10 10-3-3
– parity-violating electron scattering: M=mparity-violating electron scattering: M=mWW , , new new 1010-3-3
– Also, suppression QQWWe,pe,p 1-4 sin 1-4 sin22WW 0.1 0.1
P. Langacker ICHEP2004 (8/16/04)
(Shufang Su)
P. Langacker ICHEP2004 (8/16/04)
RPVRPV95% CL95% CL
MSSMMSSMlooploop
Kurylov, Ramsey-Musolf, Su (2003)
P. Langacker ICHEP2004 (8/16/04)
SLAC E158 Moller Scattering
e-e- polarization asymmetry, P = 85%I + II prelim: s2=0.0021Compositeness scale: 10 TeV; Z’ ~0.8 TeVRun III (summer 04): 0.0015 (Kolomensky talk on E158 website)
(Run I)
P. Langacker ICHEP2004 (8/16/04)
P. Langacker ICHEP2004 (8/16/04)
P. Langacker ICHEP2004 (8/16/04)
P. Langacker ICHEP2004 (8/16/04)
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Qweak (Jlab)s2~0.0007Complementary to MollerForm factors can be measured
P. Langacker ICHEP2004 (8/16/04)
Atomic Parity Violation• Very sensitive to Z’, leptoquarks, RPV• Washington: thallium (optical rotation) 1%,
but theory 2.7% • Boulder: cesium (Stark)
– QW = -72.69(48) (SM: -73.19(3))– “turbulent 2 yr” (Breit, vacuum pol., Z vertex, nuclear
skin)– Anapole: discrepancy with nuclear physics expectations
• Future– Paris cesium- may become competitive– Berkeley: Yb isotopes (wave functions cancel, but
nuclear radius; reduced sensitivity to new physics)– Washington: Ba+ ions (0.1% may be possible)– KVI: Ra+ considered
P. Langacker ICHEP2004 (8/16/04)
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NuTeVNC/CC; and -bar3 discrepancy in RN
P. Langacker ICHEP2004 (8/16/04)
• Beyond standard model strained– Not SUSY loops or RPV– Hard to fit leptoquark– Designer Z’ possible– Mixing of- heavy + more miracles
• Radiation from final lepton in cc (needs checking)• NLO QCD: suppressed by sin4W but may be important
– New analysis very important
• Nuclear effects unlikely• 30% s-sbar asymmetry possible (controversial)• 5% isospin breaking possible, but naively expect 0.5%
– NOMAD, Qweak, other JLAB
P. Langacker ICHEP2004 (8/16/04)
NOMAD
• e oscillations• Deep inelastic scattering
(CC and NC)• Expect 1% sin2W QuickTime™ and a
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P. Langacker ICHEP2004 (8/16/04)
Outlook
•NOMAD•QWEAK
•Possible APV•Possible reactor e-bar, in conjunction with oscillation experiment ( s2
W~0.001)•Near detectors for long baseline?•Neutrino factory?
P. Langacker ICHEP2004 (8/16/04)
CKM Universality• |Vud|2 + |Vus|2 + |Vub|2 ~ |Vud|2 + |Vus|2 1 –
– PDG 2002: = 0.0042 ± 0.0019– New physics? Constrains heavy explanations of
NuTeV– Problem in Vud?
• Superallowed: |Vud|=0.9740(5), many checks• Neutron: 0.9745 (16) (common structure-
independent rad corr)• Pion beta decay: 0.9716(39) (new)
– Problem in Vus?
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• PDG value mainly from old Ke3. Radiative corrections?• New BNL865 K+, KTEV KL, KLOE KS consistent with =0.• Not CERN NA48.• Also hyperon decay data (theory errors)
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(C. Quigg)
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The BNL g-2 experiment
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• Discrepancy between e+e- and decay
• New e+e- data• Work on isospin violation• Hadronic light by light• If real discrepancy then SUSY
with large tan and low masses is possibility: tan /(MSUSY/100 GeV)2~2
• Proposal to improve experimental error by 2
• Can theory error keep up?
P. Langacker ICHEP2004 (8/16/04)
Electric Dipole Moments• New probe of T (CP) violation• New phases needed for
baryogenesis• EDMs small in SM, large in most
BSM, e.g. SUSY• MSSM: 62 new real parameters
and 43 new phases– Universal soft breaking => two new
phases A = arg(A* m1/2), B = arg(B* m1/2) (300 GeV/m)2 sin A,B < 10-2
T
Sd
P
Electron EDM in various SM extensionsnot renormalizable loop diagrams
2
5 ψγψ Fe =Lγ
eeExperimental limit:|de| < 1.610-27 ecm
Physics model |de|Standard Model ~10-41 e·cm
Left-right symmetric 10-26-10-28 e·cm
Lepton flavor-changing 10-26-10-29 e·cm
Multi-Higgs 10-27-10-28 e·cmTechnicolor 10-27-10-29 e·cm
Supersymmetry < 10-25 e·cm
B. Regan, E. Commins, C. Schmidt,
D. DeMille, PRL 88, 071805 (2002)
Models assumenew physics at ~100 GeV& CP-violating phases ~1
(D. DeMille)
P. Langacker ICHEP2004 (8/16/04)
P. Langacker ICHEP2004 (8/16/04)
n (ILL,PNPI)
Hg (Seattle)
Tl (Berkeley)
EDM <710-26 <210-28 <110-24 dn 710-26 210-25 de 1510-27 1.610-27 QCD 410-10 210-10 q/l, SUSY 110-2 210-3 110-2 xq/l, LR
110-2 110-3 310-2
Higgs 3/tan 0.4/tan 0.3/tan
Current status of ALL EDM searchesBest limits on “natural” parameters from 3 complementary experiments:(D. DeMille)
P. Langacker ICHEP2004 (8/16/04)
A new generation of electron EDM searches
Group System Advantages Projected gain
D. Weiss (Penn St.) Trapped Cs Long coherence ~100
D. Heinzen (Texas) Trapped C Long coherence ~100
H. Gould (LBL) Cs fountain Long coherence ?
L. Hunter (Amherst) GdIG Huge S/N 100?
S. Lamoreaux (LANL) GGG Huge S/N 100?-100,000?
E. Hinds (Imperial) YbF beam Internal E-field 2-?
D. DeMille (Yale) PbO* cell Internal E-field 100-10,000?
E. Cornell (JILA) trapped HBr+ Int. E + long T ??
N. Shafer-Ray (Okla.) trapped PbF Int. E + long T ??
(D. DeMille)
P. Langacker ICHEP2004 (8/16/04)
Flavor Violation• Lepton flavor almost conserved in SM (up to m)• Violated in SUSY, multi-Higgs, heavy , leptoquark,
non-universal Z’, compositeness• MECO (BNL): (N->eN)/(N->N) to 2 x 10-17
– Sensitive to many BSM– SINDRUM: 6.1 x 10-16
– Future: PRIME at PRISM: 10-18
• also, ->eγ at PSI: 10-13 (2 orders)• Rare B, K decays? E.g., B-> Ks (Belle, not BaBar), K;
K -> -bar • (Tree level Z’ vs SM and SUSY loops.)
P. Langacker ICHEP2004 (8/16/04)
P. Langacker ICHEP2004 (8/16/04)
TWIST• Measure decay
electron spectrum/angular distribution precisely
• Sensitive to new couplings, including RHC (eg, WR)
• 2 x 10-4 in 05/06
€
MWR (GeV )
€
Pμξ
€
Pμξδρ€
TWIST ρ
€
TWIST Pμξ
Left/Right Mixing constraints –
Anticipated TWIST Sensitivity
Mix
ing
angl
e
P. Langacker ICHEP2004 (8/16/04)
Summary• Intellectual prospects in high energy physics have never been
higher• Theoretical opportunities for standard model of everything, but
must make connections• Experimental exploration of TeV scale and beyond• Collider searches: LHC is likely to be a rich but complicated
discovery machine• Precision, rare/suppressed, neutrino experiments will give
complementary constraints• 10 yr ago: almost every extension of SM yields neutrino
masses/mixings at some level• Now: almost every extension of SM yields EDMs, FCNC at some
level, and may be other surprises