Tabletop Experiments vs Large Accelerators Alexander Penin Karlsruhe University, Germany DESY Hamburg, April 2007 in Hunting New Physics

Preface

Search for fundamental constituents of Matter Shorter distances Higher energies Larger Accelerators

Discovery of Electron Sir J.J.Thomson (1897)

Measuring Z-boson

Alternative I Uncertainty Principle High accuracy, low scale experiments, e.g. Muon anomalous magnetic moment Muon decay spectrum (Brookhaven) (TWIST/TRIUMF) Probing high energies through quantum effects: Suppression factor

Alternative II Very subtle effects Mirror Universe Extra Dimensions New Physics of a different kind, e.g. Extreme accuracy of theory and experiment

Quantum Electrodynamics (QED)

QED = Quantum Mechanics + Relativity Nobel Prize 1965 (R.Feynman, J.Schwinger, S.Tomonaga) Great success Electron anomalous magnetic moment Fading interest “Landau Pole” Strong and Weak interactions Renaissance Positronium Bhabha scattering

Positronium

Discovery of Positron TheoryExperiment Paul Dirac (1928)Carl Anderson (1932)

Positronium CV First time mentioned (S.Mohorovicic) 1945 – Baptized (A.E.Ruark) 1951 – Discovered (M.Deutch) Hydrogen-like bound state of and

Binding energy Radius Positronium Main Features Hadronic effects negligible Spin Parapositronium Orthopositronium

Positronium Main Features II Hyperfine splitting

Positronium Main Features III Decay rate Lifetime

Quantum mechanics Early days of quantum field theory, noncovariant perturbation theory. Feynman‘s covariant perturbation theory. ``...there is a moral here for us. The artificial separation of high and low frequencies, which are handled in different ways, must be avoided'' Beginning of the nonrelativistic effective theory era. (Caswell, Lepage) Effective theory + Dimensional regularization s (J. Schwinger) 1986 Now s. Timeline of QED Bound States Theory

Theory vs Experiment: HFS M.W.Ritter et al. (1984) A.P.Mills, Jr. (1983) B.Kniehl, A.P. (2000); R.Hill; K.Melnikov, A.Yelkhovsky (2001)

Theory vs Experiment: HFS

Theory vs Experiment: Decays “Positronium lifetime puzzle” ( )

Theory vs Experiment: Decays Tokyo (SiO 2 powder, 2003) Michigan (vacuum, 2003) B.Kniehl, A.P.; R.Hill and G.P.Lepage; K.Melnikov, A.Yelkhovsky (2000)

Theory vs Experiment: Decays Positronium lifetime puzzle is solved !... for the moment

Running Positronium Experiments

Zürich MichiganTokyo Halle München

Lewis Carrol (1871) “Through the Looking-Glass”

Weak interactions distinguish between left and right! Nobel Prize 1957 (T.D.Lee, C.N.Yang) Parity Violation in Nature Neutron decay Standard model Nobel Prize 1979 (S.Glashow, S.Weinberg, A.Salam)

The Mirror Universe A.Salam; I.Kobzarev, L.Okun, Y.Pomeranchuk (1966) Interaction with “normal” particles Gravity (dark matter?) Mixing Mirror Universe: left right

Positronium and the Mirror Universe S.Glashow (1986) Hyperfine splitting Decay rate

The Extra Dimensions L.Randall, R.Sundrum (1999) S.Dubovsky, V.Rubakov, P.Tinyakov (2000) T.Kaluza (1921); O.Klein (1926) Compact extra dimensions Infinite extra dimensions Matter can escape into the extra dimensions! Invisible at low energies

Positronium and the Extra Dimensions Decay rate Gravitational potential

Bhabha Scattering

H.J.Bhabha (1935)

Luminosity of Colliders Bhabha scattering is the “standard candle” Easy to measure QED dominated

BABAR/PEP-II, BELLE/KEKB, BES/BEPC, High energy colliders:LEP, ILC Low energy colliders: KLOE/DAPHNE, VEPP-2M,... Luminosity of Colliders

GigaZ/ILC KLOE, CMD

H.J.Bhabha (1935) R.Bonciani et al.; A.P. (2005) Radiative Corrections

Summary In the ultimate era of giant accelerators we should not forget the tabletop experiments After a rise and a fall, QED stocks are traded high again