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PHYS 5326 – Lecture #11

Monday, Feb. 24, 2003 Dr. Jae Yu. PHYS 5326 – Lecture #11. Brief Review of sin 2 q W measurement Neutrino Oscillation Measurements Solar neutrinos Atmospheric neutrinos A lecture on neutrino mass (Dr. Sydney Meshkov from CalTech). Next makeup class is Friday, Mar. 14, 1-2:30pm, rm 200.

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PHYS 5326 – Lecture #11

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  1. Monday, Feb. 24, 2003 Dr. JaeYu PHYS 5326 – Lecture #11 • Brief Review of sin2qW measurement • Neutrino Oscillation Measurements • Solar neutrinos • Atmospheric neutrinos • A lecture on neutrino mass (Dr. Sydney Meshkov from CalTech) • Next makeup class is Friday, Mar. 14, 1-2:30pm, rm 200. PHYS 5326, Spring 2003 Jae Yu

  2. How is sin2qW measured? • Cross section ratios between NC and CC proportional to sin2qW • Llewellyn Smith Formula: PHYS 5326, Spring 2003 Jae Yu

  3. SM Global Fits with New Results Without NuTeV c2/dof=20.5/14: P=11.4% With NuTeV c2/dof=29.7/15: P=1.3% Confidence level in upper Mhiggs limit weakens slightly. LEP EWWG: http://www.cern.ch/LEPEWWG PHYS 5326, Spring 2003 Jae Yu

  4. Tree-level Parameters: r0 and sin2qW(on-shell) • Either sin2qW(on-shell) or r0 could agree with SM but both agreeing simultaneously is unlikely PHYS 5326, Spring 2003 Jae Yu

  5. Model Independent Analysis • Rn(`n) can be expressed in terms of quark couplings: • Where • Paschos-Wolfenstein formula can be expressed as PHYS 5326, Spring 2003 Jae Yu

  6. Model Independent Analysis Difficult to explain the disagreement with SM by: Parton Distribution Function or LO vs NLO or Electroweak Radiative Correction: large MHiggs PHYS 5326, Spring 2003 Jae Yu

  7. Linking sin2qW with Higgs through Mtop vs MW One-loop correction to sin2qW PHYS 5326, Spring 2003 Jae Yu

  8. where and . Oscillation Probability • Substituting the energies into the wave function: • Since the n’s move at the speed of light, t=x/c, where x is the distance to the source of nm. • The probability for nm with energy En oscillates to ne at the distance L from the source becomes PHYS 5326, Spring 2003 Jae Yu

  9. Why is Neutrino Oscillation Important? • Neutrinos are one of the fundamental constituents in nature • Three weak eigenstates based on SM • Left handed particles and right handed anti-particles only • Violates parity  Why only neutrinos? • Is it because of its masslessness? • SM based on massless neutrinos • Mass eigenstates of neutrinos makes flavors to mix • SM in trouble… • Many experimental results showing definitive evidences of neutrino oscillation • SNO giving 5 sigma results PHYS 5326, Spring 2003 Jae Yu

  10. n Sources for Oscillation Experiments • Must have some way of knowing the flux • Why? • Natural Sources • Solar neutrinos • Atmospheric neutrinos • Manmade Sources • Nuclear Reactor • Accelerator PHYS 5326, Spring 2003 Jae Yu

  11. Oscillation Detectors • The most important factor is the energy of neutrinos and its products from interactions • Good particle ID is crucial • Detectors using natural sources • Deep under ground to minimize cosmic ray background • Use Cerenkov light from secondary interactions of neutrinos • ne + e  e+X: electron gives out Cerenkov light • nm CC interactions, resulting in muons with Cerenkov light • Detectors using accelerator made neutrinos • Look very much like normal neutrino detectors • Need to increase statistics PHYS 5326, Spring 2003 Jae Yu

  12. Name Reaction En End point (MeV) pp 0.42 pep 1.44 7Be 0.86 8B 15 Solar Neutrinos • Result from nuclear fusion process in the Sun • Primary reactions and the neutrino energy from them are: PHYS 5326, Spring 2003 Jae Yu

  13. Solar Neutrino Energy Spectrum PHYS 5326, Spring 2003 Jae Yu

  14. Comparison of Theory and Experiments PHYS 5326, Spring 2003 Jae Yu

  15. Sudbery Neutrino Observatory (SNO) • Sudbery mine, Canada • 6800 ft underground • 12 m diameter acrylic vessel • 1000 tons of D2O • 9600 PMT’s Elastic Scattering Neutral Current PHYS 5326, Spring 2003 Jae Yu

  16. SNO ne Event Display PHYS 5326, Spring 2003 Jae Yu

  17. Solar Neutrino Flux PHYS 5326, Spring 2003 Jae Yu

  18. 0.35 SNO First Results PHYS 5326, Spring 2003 Jae Yu

  19. Atmospheric Neutrinos • Neutrinos resulting from the atmospheric interactions of cosmic ray particles • nm to ne is about 2 to 1 • He, p, etc + N  p,K, etc • p m+nm • m e+ne+nm • This reaction gives 2 nm and 1 ne • Expected flux ratio between nm and ne is 2 to 1 • Form a double ratio for the measurement PHYS 5326, Spring 2003 Jae Yu

  20. Super Kamiokande • Kamioka zinc mine, Japan • 1000m underground • 40 m (d) x 40m(h) SS • 50,000 tons of ultra pure H2O • 11200(inner)+1800(outer) 50cm PMT’s • Originally for proton decay experiment • Accident in Nov. 2001, destroyed 7000 PMT’s • Dec. 2002 resume data taking PHYS 5326, Spring 2003 Jae Yu

  21. Atmospheric Neutrino Oscillations PHYS 5326, Spring 2003 Jae Yu

  22. Super-K Atmospheric Neutrino Results PHYS 5326, Spring 2003 Jae Yu

  23. Stopping m 3m Super-K Event Displays PHYS 5326, Spring 2003 Jae Yu

  24. Other Experimental Results Macro experiment Soudan 2 experiment PHYS 5326, Spring 2003 Jae Yu

  25. Accelerator Based Experiments • Mostly nm from accelerators • Long and Short baseline experiments • Long baseline: Detectors located far away from the source, assisted by a similar detector at a very short distance (eg. MINOS: 370km, K2K: 250km, etc) • Compare the near detector with the far detector, taking into account angular dispersion • Short baseline: Detectors located at a close distance to the source • Need to know flux well PHYS 5326, Spring 2003 Jae Yu

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