The Net Advance of Physics:
SUPERLUMINAL NEUTRINOS
Theories with Neutrino Speed Less Than, or Equal to, Light Speed

Various effects which could perhaps create the illusion of superluminal motion in neutrinos. In alphabetical order.

• Changes in Composition or Strength of Beam as it Travels:
  • A possible statistical mechanism of anomalous neutrino velocity in OPERA experiment? by Robert Alicki [2011/09] Damping makes a Gaussian packet seem to move faster than it really does.
    • On the Apparent Superluminal Motion of a Damped Gaussian Pulse by Norman Hugh Redington [2011/12] Argues that the Alicki effect exists, but probably does not explain OPERA results.
  • A simple explanation of OPERA results without strange physics by Gilles Henri [2011/10] Distortion of an almost-square pulse in transit.
  • A classical model explaining the OPERA velocity paradox by Bogusław Broda [2011/10]
  • Possible Origin Of The Neutrino Speed Anomaly Reported By OPERA by Shlomo Dado and Arnon Dar [2011/10] Argue that thermal expansion and expulsion of target material along the beam by the pulse causes column density of the target to decrease with time, distorting the shape of the received pulse.
  • 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]

• Coherent Neutrinos:
  • Using an Einstein's idea to explain OPERA faster than light neutrinos by Rafael Torrealba [2011/10] Meaning stimulated emission, a sort of neutrino laser.
  • Apparent superluminal neutrino propagation caused by nonlinear coherent interactions in matter by Ram Brustein and Dmitri Semikoz [2011/10]
  • OPERA superluminal neutrinos explained by spontaneous emission and stimulated absorption by Rafael Torrealba [2011/12]

• Dark Matter:
  • 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.

• Flavour-Oscillation Effects:
  • Neutrino Velocity and Neutrino Oscillations by H. Minakata and A. Yu. Smirnov [2012/02] Study group velocities in the presence of mixing, which distorts packets. Find this cannot explain OPERA's result.

• Gravitational Effects:
  • Slow photon delay and the neutrino velocity by Gustavo R. Gonzalez-Martin [2011/10]
  • 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.
    • General relativity and OPERA Experiment by Christian Corda [2012/01] Against the theory of Garcia-Islas.
  • Relativity accommodates superluminal mean velocities by Bartolome Alles [2011/11] But the effect is still too small to explain OPERA.
  • Speed of the CERN Neutrinos released on 22.9.2011 - Was stated superluminality due to neglecting General Relativity? by Wolfgang Kundt [2011/11]
  • Reduced Photon Velocities in Agreement with the OPERA Neutrino Experiment by James D. Franson [2011/11] Proposes that gravity slows light but not neutrinos.
  • The Witte Effect: the Neutrino Speed and the Anisotropy of the Light Speed, as Defined in the General Theory of Relativity by Policarpo Yōshin Ulianov [2012/01]
    • Witte-Ulianov Rotation Anisotropy Effect.rotating the Einstein's Light Clock, to Show that the Neutrinos Travel at the Light Speed in Opera and Minos Experiments. by Policarpo Yōshin Ulianov [2012/01]
    • Anomalous Gravitational Acceleration and the Opera Neutrino Anomaly by David Brown [2012/02] Suggests that MOND and the Pioneer anomaly may influence timing.
    • A Conceptual Framework for Understanding Faster-Than-Light Neutrinos by Eric Sakk and Aradhya P. Kumar [2012/02] Argue that, at small scales, spacetime has a Kerr-type metric, and path-lengths are therefore shorter than a large-scale observer expects.
    • The road toward a general relativistic metric inside the Earth and its effect on neutrino travel from CERN to GRAN-SASSO Laboratory by Olivier Besida [2012/05]

• Phase-Velocity, Group-Velocity, and Wave-Packet Effects: Phase velocities, of course, can exceed the speed of light. So (under particular circumstances) can group velocities. In neither case, however, is information actually transmitted, so Lorentz invariance survives. Broadening of a wave-packet (as would happen, for example, if its component waves move at different speeds) can also make it difficult to recognise whether a "velocity" associated with the packet is physically meaningful. Therefore, experimenters need to be careful about what they are measuring.
  • Fast Light, Fast Neutrinos? by Kevin Cahill [2011/09] Analogy with superluminal group-velocity in optics.
  • Is OPERA Neutrino Superluminal Propagation similar to Gain-Assisted Superluminal Light Propagation by Vladan Pankovic [2011/09]
  • OPERA Collaboration have observed phase speed of neutrino wave function by Shi-Yuan Li [2011/10] This seems to be a general discussion of the issue rather than a specific critique of OPERA.
  • Neutrino Velocity Anomalies: A Resolution without a Revolution by Dmitry V. Naumov and Vadim A. Naumov [2011/10] Argue that large tranverse size of the eigenmass wavepacket leads to superluminal illusion.
    • Comment by Denis Bernard [2011/10] Attempts to refute Naumov and Naumov.
  • Superluminal group velocity of neutrinos by Antonio Mecozzi and Marco Bellini [2011/10]
    • Group velocity of neutrino waves by D. Indumathi et al. [2011/10] Follow-up to Mecozzi and Bellini; finds this effect, although real, cannot explain OPERA results.
    • Superluminal Group Velocity of Neutrinos : Review, Development and Problems by Kazuyuki Fujii [2012/03]
  • Superluminal group velocity through maximal neutrino oscillations by Tim R. Morris [2011/10] The group-velocity effect is real, but cannot explain the OPERA results.
  • Wave packet distortion and superluminal neutrinos by Maurizio De Sanctis [2011/10]
  • Some light on "Measurement of the neutrino velocity with the OPERA detector in the CNGS beam" by Ivan Area and X. Prado [2011/10] Dispersion broadens the wavepacket, but this can only produce a pseudo-superluminal effect in the non-relativistic case.
  • The Neutrino and the Photon by Rodney Bartlett [2012/01] Brief, entirely qualitative argument.
  • Wave Packet for Massless Fermions and its Implication to the Superluminal Velocity Statistics of Neutrino by Kelin Wang and Zexian Cao [2012/01]
  • Third road to the OPERA: a tunnel after all? by Giovanni Amelino-Camelia [2012/01] Peak-to-peak speed not speed of information.
  • Neutrino Velocity and Neutrino Oscillations by H. Minakata and A. Yu. Smirnov [2012/02] Study group velocities in the presence of mixing, which distorts packets. Find this cannot explain OPERA's result.
  • The homogeneous 5D projection and realization of quark and hadron masses by Kai-Wai Wong et al. [2012/02] Although it is not the main subject of their paper, the authors argue in passing that a wavepacket composed of massless neutrinos could look like a superluminal, massive particle.

• Quantum Fields:
  • Virtual Speed of Neutrino by Arnab Shome [2012/01] Argues qualitatively that annihilation events in vacuum change length of path traversed.

• Quantum Weak-Measurement:
  • Apparent Superluminal Muon-neutrino Velocity as a Manifestation of Weak Value by Shogo Tanimura [2011/10]
  • Can apparent superluminal neutrino speeds be explained as a quantum weak measurement? by M. V. Berry et al. [2011/10] The abstract reads in its entirety: "Probably not."

• Reference-Frame Effects:
  • Comment on superluminality in general relativity by Dieter Lust and Marios Petropoulos [2011/10] Argues that a luxon can appear to move faster than light in certain general-relativistic reference frames.
  • On the Neutrino Opera in the CNGS Beam by Armando V. D. B. Assis [Progress in Physics 4, 85 (2011)] Special relativistic kinematics of a rotating frame leads to impression of superluminal velocity.
    • Comment by Armando V. D. B. Assis [2011/09] Adds a more detailed calculation.
  • Time-of-flight between a Source and a Detector observed from a Satellite by R. A. J. van Elburg [2011/10]
  • Does OPERA probe that the Earth is moving ? by Dominique Monderen [2011/10]
  • Witte-Ulianov Rotation Anisotropy Effect: rotating the Einstein's Light Clock, to Show that the Neutrinos Travel at the Light Speed in Opera and Minos Experiments. by Policarpo Yōshin Ulianov [2012/01]
  • Are OPERA neutrinos faster than light because of non-inertial reference frames? by Claudio Germana [2012/01] "The analysis presented here is falsifiable because it predicts that performing the experiment from January to March/April, the neutrino beam will be detected to arrive 50 ns later than light. "
  • Local Doppler effect, index of refraction through the Earth crust, PDF and the CNGS neutrino anomaly? by Armando V. D. B. Assis [2012/02]

• Temperature Should Be Included in the Relativistic Velocity-Formula:
  • Neutrino speed and temperature by Marco Matone [2011/11]

THE NET ADVANCE OF PHYSICS --- Superluminal Neutrinos