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Recent and Future Experiments on Determination of Vud in Particle Physics

This talk discusses the significance of first-generation particles in contemporary physics, emphasizes the high precision required in particle physics experiments, and explores the measurement of Vud in neutron and nuclear beta decays. The presentation outlines past experiments, discusses unitarity in quark mixing, and reviews key observations in neutron decay that led to the determination of Vud. Future trends and advancements in experimental techniques are also highlighted, along with upcoming experiments and technical developments in low-energy particle physics.

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Recent and Future Experiments on Determination of Vud in Particle Physics

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  1. Recent and future experiments for the determination of Vud Hartmut Abele International WE Heraeus Summer School on Flavour Physics and CP Violation Technische Universität Dresden, 29 August - 7 September 2005

  2. Low energy particle physics • Talk about the firstparticle flavour: • First generation´s particles make up our contemporary universe • They are stable • They have zero energy • They contribute to particle physics mainly because of their extremely high precision High energy particle physics Tera-eV Neutron pico-eV

  3. MPL  = 1/128 GUT  = 1/137 quantum gravity MnPL

  4. Window to "new physics" GUT

  5. Possible CP violation in neutron physics and Two motivations to measure EDMs EDM is effectively zero in standard model but big enough to measure in non-standard models direct test of physics beyond the standard model EDM violates T symmetry Deeply connected to CP violation and the matter-antimatter asymmetry of the universe

  6. A bit of history neutron: Electro- 10-20 10-20 magnetic electron: 10-22 10-22 10-24 10-24 Experimental Limit on d (e.cm) 10-26 Multi SUSY Higgs f ~ 1 10-28 f ~ a/p Left-Right 10-30 10-30 1960 1970 1980 1990 2000 10-32 10-34 Highest Precision: Energy: E ~ 10-22 eV (n-El.Dipole Moment: E/ħ ~ 1/month) Standard Model 10-36 10-38

  7. Sensitivity of neutron experiments: Energy: E ~0.000 000 000 000 000 000 000 1eV = 10-22 eV Momentum: p/p ~ 10-11 (n-charge: angular resolution of 1Å on 10m) Finestructure constant / ~ 10-8 (measurement of:nvn) Lifetime / ~ 10-3

  8. Neutron moderation Neutrons: • hot • thermal • cold • ultracold

  9. From hot to cold neutrons

  10. ILL Neutron Guide Hall Gravitation and Bound Quantum States Particle Physics: SM Tests 3D Neutron Tomography

  11. OutlineMeasurement of Cosine Cabibbo Vud • Situation 2004 • Ways to extract Vud • Vud from neutron beta-decay: Inputs: 1. Correlation A, 2. lifetime tau • Vud from nuclear beta-decay, 100 inputs • A new measurements of correlation A • Future trends • Sources • Experiments

  12. Quark Mixing and CKM Unitarity • Standard Model: • quark-mixing should be 'zero-sum game': • quark mixing = pure rotation in flavor space • i.e. CKM quark mixing matrix should be unitary • Vud from • Nuclear beta-decay • Neutron beta-decay • Pion beta-decay

  13. Unitarity check Vub 0.00001% Vus 5% Mixing of quarks = rotation in flavor-space: Test in first row: |Vud|2 + |Vus|2 + |Vub|2 ≈ cos2θ + sin2θ + 0 < 1 ? : Cabibbo Vud 95%

  14. Situation untill 2004 • Check unitarity via elements of the first row: • Vus and Vub from particle physics data (K and B meson decays) • From nuclear β decay (world average 2004): • Vud obtained from avg. Ft and GA from muon decay • From particle physics (neutron decay): • Vud obtained from neutron β decay asymmetry A and lifetime t [I.S. Towner & J.C. Hardy, submitted to Phys. Rev. C (2005)] Δ = 0.0034(14) (PDG 2004) [H. A. et al., PRL 88 (2002) 211801]

  15. A Neutron Spin Electron B Neutrino C Proton Correlation measurements in -decay Observables in neutron decay: Lifetime  Spin Momenta of decay particles

  16. Neutron Spin A A Neutron Spin Electron Electron Vud from neutron beta-decay Only 2 measurements: 1.Lifetime t 2.Correlation coefficient A() Vud =0.9717(13) = 0.9717(tau:4)(theory:2)(A:12) = gA/gV

  17. PROCESSES WITH SAME FEYNMAN DIAGRAM: • Solar cycle p p  D e+ e p p e  D e … • Neutron star formation p e n e • Primordial element formation n e+  p e'p e n e n p ee' • Neutrino detectors p e'  n e+ • Neutrino forward-scatteringe p e+ n etc. • W, Z-production p p'  W  ee' etc. = gA/gV

  18. Correlation ASpectrometer PERKEO II Magnetic field Polarizer Spin flipper Cross section neutron beam

  19. The new A, (B, C) measurement 2004University of Heidelberg, ILL • Precise Electron Spectroscopy • Proton detection • Asymmetry A, B, C • A new beam: decay rate 1 MHz/m • The ‘ballistic’ super-mirror cold-neutron guide H113 • H. Haese et al., Nucl. Instr. Meth. A485, 453 (2002) • New Polarizers (TU Munich, ILL) • New Geometry for Beam polarization • A perfectly polarized neutron beam • Signal to Background > 1000 : 1

  20. The new A measurement • Precise Electron Spectroscopy • Asymmetry A Status 2002 • A new beam: decay rate 1 MHz/m • The ‘ballistic’ super-mirror cold-neutron guide H113 • H. Haese et al., Nucl. Instr. Meth. A485, 453 (2002) • New Polarizers (TU Munich, ILL) • New Geometry for Beam polarization • A perfectly polarized neutron beam • Signal to Background > 1000 : 1 Status 2004 Daniela Mund et al., preliminary

  21. 2002: final result:A = -0.1189(7)  = -1.2739(19)

  22. The future

  23. Technical developments:New sources • SNS, Oak Ridge, Tennessee:

  24. FRM2 2005 • UCN source PSI • UCN source at Vienna • UCN Source at Mainz • Cold neutrons at the FRM II • UCN source at the FRM II

  25. Experiments: Angular correlations in neutron decay Mainz, Munich • New developments: hep-ph/0312124 CKM-Workshop, Sep. 2002, PMSN-Workshop, NIST 2004 • “little” a: aSpect, Mainz, Munich,2005 • “Big” A,B,C: HD, 2004 • “Big” A, small terms: HD, 2006 • “little” a: NIST • “Big” A: LANL,... • “abBA”: abBA-Collaboration • “Big A + B”: Gatchina • “Big” R: PSI, ongoing • “Big” D: emiT, • “Big” D: Trine ? • “Fermi”: HD, Mz, TUM, 2008/2009 LANSL TRINE 2000

  26. PERKEO III, Correlation A, University HD neutron cloud detector proton or electron detector ~2m, 150mT velocity selector neutron beam chopper beam stop decay volume Dubbers, Märkisch, H.A.

  27. Particles And Fields matrix for d-u transition: hadron and lepton currents: vector- and axial vector currents: Lagrange function for neutron decay:

  28. aSPECT, correlation a, University Mz/TUM Proton spectroscopy

  29. 2. The lifetime of the neutron • Methode: store UCN in bottles • Early universe: first 3 minutes • Nukleo synthesis: H, D, 3He, 4He, Li • Quark mixing • Input für Vud, 1. Element of CKM Matrix • Precision / ~ 10-3 TUM NIST

  30. 2. The lifetime of the neutron • Methode: store UCN in bottles • Early universe: first 3 minutes • Nukleo synthesis: H, D, 3He, 4He, Li • Quark mixing • Input für Vud, 1. Element of CKM Matrix • Precision / ~ 10-3 TUM NIST

  31. Neutron lifetime t NIST: Mampe et al., PRL 63 593 (1989) Huffmann et al., Nature Munich: ri = 15 cm Ra = 30 cm

  32. The Neutron Lifetime and Big Bang Nucleo Synthesis • Problem 1s after Big Bang: • What does a gas of n and p, when the universe expands and the temperature drops? • Inputs: • neutron lifetime tau • Cross sections • neutrino cross-sections   1/tau • nuclear physics 0.1 – 1 MeV (measured!) • Outputs: H, D, He, Li • number of particle families N • density  of (ordinary) matter in universe

  33. The Neutron Lifetime and Big Bang Nucleo Synthesis • Problem 1s after Big Bang: • What does a gas of n and p, when the universe expands and the temperature drops? • Inputs: • neutron lifetime tau • Cross sections • neutrino cross-sections   1/tau • nuclear physics 0.1 – 1 MeV (measured!) • Outputs: H, D, He, Li • number of particle families N • density  of (ordinary) matter in universe

  34. Vud from neutron b-decay Wilkinson 1982, CKM Workshop September 2002: Marciano et Sirlin

  35. 2002: Free Parameters, Standard Model Ft-values Neutron Deviation from unitarity Visible in the “raw” data! hep-ph/0312124 hep-ph/0312150 Vud=0.9717(13) (4:)(12:A)(2:theory)

  36. Free Parameters, Standard Model Ft-values Neutron Deviation from unitarity Visible in the “raw” data! hep-ph/0312124 hep-ph/0312150 Vud=0.9717(8) (4:)(7:A)(2:theory)

  37. Weak Interaction symmetry tests, CVC hypothesis dm/m < 3·10-8 Vud from nuclear beta decays • Q – Decay energy  mass m • T1/2 – Half-life • b – Branching ratio • PEC – Electron capture fraction • δR– Radiative correction • δC– Isospin symmetry breaking correction

  38. Vud from superallowed β decay Wilkinson 2005

  39. GV=GFVud

  40. but • …

  41. 46 V • Savard et al. (2005): Q value increases (2005) • Vud= 0.97363(44)  0.97280(36) • Now bad fit • But average still Vud= 0.9739  0.9738(36)

  42. 42 Sc • Kaon 2005, R. Segal: • Q value remeasured • Agrees with V • All Q values must be remeasured (B. Marciano)

  43. Blaum et al.: Carbon Cluster as Reference Masses

  44. Summary • This was a talk about a wellknown unknown: Cabibbo angle Vud • Remeasurement of the beta asymmetry • Improvement by factor 2 • We need new lifetime measurements (2 years) • We need Q value (mass measurements) in nuclear beta-decays

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