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Superluminal neutrinos at OPERA (experimental results and phenomenology)

Superluminal neutrinos at OPERA (experimental results and phenomenology). Group meeting November 8, 2011 Würzburg, Germany Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Preamble.

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Superluminal neutrinos at OPERA (experimental results and phenomenology)

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  1. Superluminal neutrinos at OPERA(experimental results and phenomenology) Group meeting November 8, 2011 Würzburg, GermanyWalter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAAAAA

  2. Preamble • Sept. 22, 2011: OPERA long-baseline experiment has reported v/c-1 ~ 2.5 10-5 at 6s (for nm nm; 60.7ns faster than light over 730km baseline) • Since then (Nov. 7): 129 papers discussing that ~ 2.8/calender day • Why so striking? Probably systematical error not accounted for, but if confirmed, evidence for Lorentz invariance violation? One of the major breakthroughs of this century?

  3. Contents • The OPERA time-of-flight measurement • Interpretations, phenomenological observations • Generic constraints on interpretations from the OPERA result itself

  4. Neutrino production • Technical layout: • Flavor composition: mostly nm • Energy spectrum:<E> ~17 GeV(higher than “typical“ n beams) (OPERA, arXiv:1109.4897) (CNGS, IEEE06, Monte Carlo!)

  5. Time-of-flight measurement (OPERA, arXiv:1109.4897)

  6. Known time delays • Found effect ~ 6% of that! [60.7 ns] Interpretation? (OPERA, arXiv:1109.4897)

  7. Proton versus neutrino waveforms • 1048.5ns – 987.8ns (corrections) = 60.7 ns Protons Neutrinos (OPERA, arXiv:1109.4897)

  8. OPERA self-cross checks • Two extractions (two proton waveforms),time dependencemonitored Hardly any energy dependence found (OPERA, arXiv:1109.4897)

  9. Possible interpretations? • Lorentz invariance violation (e. g. different dispersion relation)? • Environment-dependent effect? • Sterile neutrinos, such as taking shortcuts through an extra dimension? • Experimental effect, not accounted for? Unknown systematics? • Problem with statistics treatment? • S. Parke: Most stringent test of the GPS system?

  10. Phenomenological observations • SN 1987A neutrinos obviously without significant advance (E ~ 10 MeV; electron ns) • MINOS and other experiments measuring in the same energy range without significant conclusions • Some flavor or energy dependence of effect? (incl. a bias correction for Fermilab 79; from arXiv:1110.6577)

  11. Theoretical observations • Neutrino oscillations (not flavor mixing!) between two mass eigenstates with very different velocities average out[however: not observed at OPERA …] • Cohen-Glashow bound (next week) • Sterile neutrino easiest workaround? • Can also “tune“ the energy easily (well known for matter effects in neutrino oscillations; see e.g. arXiv:1110.4871)

  12. Experimental observations • The proton and neutrino waveforms may not be the same • E.g. some averaging in the beam current transformer affects leading and trailing edges (arXiv:1110.0595)

  13. What can we learn from OPERA data? • However: not only leading an trailing edges match, also complicated proton waveform at “plateau“ • Example: Exaggerated 200ns Gaussian filter (blue, dotted) affects g.o.f. • Consequence:any effect which deteriorates proton waveform decreases g.o.f. (WW, arXiv:1110.0424)

  14. Consequences Experimental example:Gaussian filter (protons  neutrinos) Theoretical example:Fraction X of superluminal neutrinos Steriles (WW, arXiv:1110.0424)

  15. Summary • OPERA result striking • Challenging to find a good interpretation because • Cohen-Glashow bound • Energy-dependent effect? • Proton waveform reproduced • More on theoretical matters: Martin Krauss, next week

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