The Net Advance of Physics:
SUPERLUMINAL NEUTRINOS
2011 OPERA Experiment

The following papers discuss this experiment (or attempts to replicate it) very specifically; other papers linked elsewhere in these pages, including nearly all published circa 2011 September, contain additional discussion. Papers arguing for a conventional explanation (other than a simple mistake) are listed under Slower-Than-Light Neutrino Theories. Papers which address the implications of this experiment for a particular theoretical proposal are listed under Faster-Than-Light Neutrino Theories.

• Measurement of the neutrino velocity with the OPERA detector in the CNGS beam by T. Adam et al. [2011/09] Much-discussed claim that a beam of mu neutrinos travelled from CERN to Gran Sasso faster than light. This is the original version; the last version effectively retracts the claim.
  • Update: Press Release from CERN [2011 November 18] Widely-separated 3ns pulses.
  • Update: Press Release from CERN [2012 February 23] Announces "two possible effects that could have an influence on its neutrino timing measurement... one would increase the size of the measured effect, the other would diminish it."
  • Update: Press Release from CERN [2012 June 8] "Neutrinos sent from CERN to Gran Sasso respect the cosmic speed limit ... Borexino, ICARUS, LVD and OPERA all measure a neutrino time of flight consistent with the speed of light."

• 60.7 Nanoseconds: A novel of life at CERN in 2011-2013 by Gianfranco D'Anna. [2016]

• A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS by M. Antonello et al. [2011/10] Found none.
• The Phantom of the OPERA: Superluminal Neutrinos by Bo-Qiang Ma [2011/11]
• Measurement of the neutrino velocity with the ICARUS detector at the CNGS beam by M. Antonello et al. [2012/03] Result: v = c.
• Determination of a time-shift in the OPERA set-up using high energy horizontal muons in the LVD and OPERA detectors by N. Yu. Agafonova et al. [2012/06] Find a systematic discrepency existed as early as 2008 between OPERA's timing system and the LVD detector also at Gran Sasso. Both experiments had to take into account the fact that the mountains near Gran Sasso are unusually transparent to cosmic-ray muons, and therefore both collected muon-arrival data, making possible a coincidence study.
  • Time-Shift in the OPERA set-up: proof against superluminal neutrinos without the need of knowing the CERN-LNGS distance and Reminiscences on the origin of the Gran Sasso Lab, of the 3rd neutrino and of the "Teramo Anomaly" by Antonino Zichichi [2012/06]
  • GPS-based CERN-LNGS time link for Borexino by B. Caccianiga et al. [2012/07]
• Phenomenology of Philosophy of Science: OPERA data by Giovanni Amelino-Camelia [2012/06]
• Analysis of the MACRO experiment data to compare particles arrival times under Gran Sasso by Francesco Ronga [2012/08]
• Precision measurement of the neutrino velocity with the ICARUS detector in the CNGS beam by M. Antonello et al. [2012/08] "The measured neutrino time of flight is compatible with the arrival of all events with speed equivalent to the one of light."
• Some Considerations on Neutrinos and on the Measurement of their Velocity by Giorgio Giacomelli [2013/04] A talk about the OPERA affair to a general audience.
• Measurement of the Velocity of the Neutrino with MINOS by P. Adamson et al. [2014/08] The result is technically superluminal, but the uncertainty in the experiment is compatible with c or less.

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• Did OPERA take into account Bremsstrahlung? This topic now has its own page.

• Did OPERA take into account the motion and geology of the Earth? Clearly, the Earth is spinning so the target was not stationary. Moreover, the beam travelled underground.
  • The influence of Earth rotation in neutrino speed measurements between CERN and the OPERA detector by Markus G. Kuhn [2011/10] Finds Coriolis effect too small to matter.
  • Thermal expansion of the earth and the speed of neutrinos by C. S. Unnikrishnan [2011/10]
  • Time-of-flight between a Source and a Detector observed from a Satellite by R. A. J. van Elburg [2011/10] In terms of special relativity. Argues that the necessary corrections are almost large enough to explain the OPERA results.
    • Comment by Armando V. D. B. Assis [2011/10] Attempts to refute van Elburg.
  • Does OPERA probe that the Earth is moving ? by Dominique Monderen [2011/10]
  • Special relativity is consistent with the opera measurements of the neutrino "velocity" by Jean-Paul Mbelek [2011/10] Argues that local radioactivity (high-velocity alpha particles) can explain OPERA results.
  • A very simple solution to the OPERA neutrino velocity problem by Juan Manuel Garcia-Islas [2011/10] Argues that gravitational red-shift will create illusion of superluminal motion when clocks on Earth are compared with those in orbit.
  • Third road to the OPERA: a tunnel after all? by Giovanni Amelino-Camelia [2012/01] Absorption by rock.
  • Local Doppler effect, index of refraction through the Earth crust, PDF and the CNGS neutrino anomaly? by Armando V. D. B. Assis [2012/02]
  • Geodesic Particle Paths Inside a Nonrotating, Homogeneous, Spherical Body by Homer G. Ellis [2012/10] Meaning of a neutrino inside the Earth.

• Did OPERA synchronise its clocks correctly?
  • Neutrino, Flying from Cern to LNGS, and Brachistochrone by G. Quznetsov [2011/09]
  • Comments on the recent velocity measurement of the muon neutrinos by the OPERA Collaboration by Jacek Ciborowski and Jakub Rembielinski [2011/09]
  • The OPERA neutrino velocity result and the synchronisation of clocks by Carlo R. Contaldi [2011/09]
    • Comment by Olivier Besida [2011/10] The author says that there are three fundamental errors in Contaldi's paper, completely invalidating its conclusions.
  • Time-of-flight between a Source and a Detector observed from a Satellite by R. A. J. van Elburg [2011/10]
    • Comment by Armando V. D. B. Assis [2011/10] Attempts to refute van Elburg.
  • A very simple solution to the OPERA neutrino velocity problem by Juan Manuel Garcia-Islas [2011/10] Argues that gravitational red-shift will create illusion of superluminal motion when clocks on Earth are compared with those in orbit.
  • Does the Opera Experiment Reveal a Systematic Error in the Satellite Ephemeris of the Global Positioning System ? by Yves-Henri Sanejouand [2011/11]
  • OPERA and the GPS by Lluís Bel [2011/12]
  • Stream of dark matter as a possible cause of the opera clocks' synchronization signals delay by Jean Paul Mbelek [2012/01] Suggests that a stream of WIMPs interferes with the photons in the GPS system.
  • Local Doppler effect, index of refraction through the Earth crust, PDF and the CNGS neutrino anomaly? by Armando V. D. B. Assis [2012/02]
  • Update: Press Release from CERN [2012 February 23] Announces "two possible effects that could have an influence on its neutrino timing measurement... one would increase the size of the measured effect, the other would diminish it."
  • Relativity, GPS, and the Validity of Common View Synchronization by Eric L. Michelsen [2012/03] Supports a straightforward approach to relativistic synchronisation.
  • Inverted Dynamics by Giorgio Capezzali [Physics Essays 29, 27 (2016)] Proposes an unconventional empirical momentum formula for tachyons on the basis of the OPERA results and other experimental data. Also (Appendix C) argues that the time measurements of the original OPERA experiment were not seriously flawed.

• Did OPERA take into account statistical factors, including uncertainty about when neutrinos left or arrived? and therefore about how long the trip took? Also, did the measured distribution of recoiling protons exactly reflect the distribution of neutrinos emitted?
  • Inconsistence of super-luminal Opera neutrino speed with SN1987A neutrinos burst and with flavor neutrino mixing by Daniele Fargion [2011/09] Asserts in passing that OPERA was probably wrong about neutrino departure times: the first appearance in the arXiv of this idea, which was the informal reaction of many physicists in late September.
  • Is there a neutrino speed anomaly? by Juergen Knobloch [2011/10] Questions whether proton particle density function was measured correctly.
  • Resolving 8 OPERA problems with superluminal neutrinos by Robert Ehrlich [2011/10]
  • Two exercises about neutrino departure times at CERN by Bernd A. Berg and Peter Hoeflich [2011/10] Written as a problem set for undergraduates.
  • A potential issue for the OPERA neutrino velocity measurement by Antonio Palazzo [2011/10] Sum and then normalise, or the other way around?
  • Narrowing of the neutrino light curve in the OPERA experiment by Maurice H. P. M. van Putten [2011/10] Finds the time-of-arrival curve to be slightly narrower than the proton PDF.
  • About Statistical Questions Involved in the Data Analysis of the OPERA Experiment by Herve Bergeron [2011/10] Finds the OPERA paper does not unambiguously show neutrino velocities are superluminal.
  • Comment on OPERA neutrino velocity measurement by Pierluigi Frabetti and Leonid Chernenko [2011/10] Argue that one of the quantities used in OPERA's maximum-likelihood analysis is not a true parameter of the PDF.
  • Statistical model uncertainty and OPERA-like time-of-flight measurements by Oliver Riordan and Alex Selby [2011/11]
  • A short comment on OPERA neutrino velocity measurement by Pierluigi Frabetti and Leonid Prokopievich Cernenko [2011/11] The "not a true parameter" issue again.
  • Can the neutrino speed anomaly be defended? by Jürgen Knobloch [2011/11] Claims to find two sources of systematic error challenging the assumption that the proton PDF exactly represents the neutrino flux.
  • Update: Press Release from CERN [2011/11] Widely-separated 3ns pulses.
  • Statistical bootstrap simulation of CNGS neutrino departure times by Bernd A. Berg [2012/01] Confirms reliability of OPERA's procedure.

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• Are the OPERA results consistent with previous observations?

  • General:
    • Inconsistence of super-luminal Opera neutrino speed with SN1987A neutrinos burst and with flavor neutrino mixing by Daniele Fargion [2011/09] Rejects OPERA superluminality claim.
    • Astrophysical consequences of the OPERA superluminal neutrino by Luis Gonzalez-Mestres [2011/09]
    • Constraints and tests of the OPERA superluminal neutrinos by Xiao-Jun Bi et al. [Phys. Rev. Lett. 107, 241802 (2011)]
    • Resolving 8 OPERA problems with superluminal neutrinos by Robert Ehrlich [2011/10]
    • Challenges Confronting Superluminal Neutrino Models by Jarah Evslin [2011/10]
    • Testing fundamental principles with high-energy cosmic rays by Luis Gonzalez-Mestres [2012/02]

  • OPERA Results vs. Atmospheric-Neutrino Data:
    • Constraints and tests of the OPERA superluminal neutrinos by Xiao-Jun Bi et al. [2011/09]

  • OPERA Results vs. Flavour-Oscillation Data:
    • Inconsistence of super-luminal Opera neutrino speed with SN1987A neutrinos burst and with flavor neutrino mixing by Daniele Fargion [2011/09] Rejects OPERA superluminality claim.
    • The Hypothesis of Superluminal Neutrinos: comparing OPERA with other Data by Alessandro Drago et al. [2011/09]

  • OPERA Results vs. Known Bounds on Lorentz Violation:
    • Neutrinos superluminality and Local Lorentz Invariance by F. Cardone et al. [2011/09] Yes.
    • Interpreting OPERA results on superluminal neutrino by Gian F. Giudice et al. [2011/09]
    • Violations of Lorentz invariance in the neutrino sector after OPERA by Luca Maccione et al. [2011/10]

  • OPERA Results for Neutrino Mass vs. Previous Measurements:
    • Comments on the recent velocity measurement of the muon neutrinos by the OPERA Collaboration by Jacek Ciborowski and Jakub Rembielinski [2011/09] This paper may assume a particular tachyon-scenario in calculating mass.

  • OPERA Results vs. Pion-Decay Data: This topic now has its own page.

  • OPERA Results vs. Stability of Neutrino:
    • Constraints from Neutrino Decay on Superluminal Velocities by J. M. Carmona and J. L. Cortes [2011/10]

  • OPERA Results vs. Supernova Data: Probably an incomplete list; most papers address this.
    • Superluminal neutrinos in long baseline experiments and SN1987a by Giacomo Cacciapaglia et al. [2011/09]
    • Inconsistence of super-luminal Opera neutrino speed with SN1987A neutrinos burst and with flavor neutrino mixing by Daniele Fargion [2011/09]
    • On the Possibility of Superluminal Neutrino Propagation by Jean Alexandre et al. [2011/09]
    • OPERA, SN1987a and energy dependence of superluminal neutrino velocity by N. D. Hari Dass [2011/10]
    • Resolving 8 OPERA problems with superluminal neutrinos by Robert Ehrlich [2011/10]
    • Superluminal neutrino speeds from SN 1987A and from OPERA experiment do agree very well by Heribert Genreith [2011/12]

  • OPERA Results for Neutrino Velocity vs. Previous Measurements:
    • OPERA-reassessing data on the energy dependence of the speed of neutrinos by Giovanni Amelino-Camelia et al. [2011/09] Finds they are compatible.

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• How did the neutrino velocity depend on energy? This topic now has its own page.

• Were all the neutrinos superluminal, or just some of them?
  • How large is the fraction of superluminal neutrinos at OPERA? by Walter Winter [2011/10]

• Did/Could OPERA violate causality?
  • Could the OPERA setup send a bit of information faster than light? by F. Giacosa et al. [2011/10] No, but the emphasis here is on "OPERA setup". If neutrinos travel faster than light, a different setup with a larger delay might violate causality, unless there is some kind of "cosmic censorship" which prevents this.

THE NET ADVANCE OF PHYSICS --- Superluminal Neutrinos