Remember the neutrino beam measurement from a few months back, when it seemed to have arrived faster than the speed of light? CERN reports that there might have been a couple of things that could have influenced the measurement of their flight times. CERN says,
The OPERA collaboration has informed its funding agencies and host laboratories that it has identified two possible effects that could have an influence on its neutrino timing measurement. These both require further tests with a short pulsed beam. If confirmed, one would increase the size of the measured effect, the other would diminish it. The first possible effect concerns an oscillator used to provide the time stamps for GPS synchronizations. It could have led to an overestimate of the neutrino’s time of flight. The second concerns the optical fibre connector that brings the external GPS signal to the OPERA master clock, which may not have been functioning correctly when the measurements were taken. If this is the case, it could have led to an underestimate of the time of flight of the neutrinos. The potential extent of these two effects is being studied by the OPERA collaboration. New measurements with short pulsed beams are scheduled for May.
So, there you go. One is the oscillator and the other has to do with a faulty optical fibre connector. Hopefully, the new measurements in May would present a clear picture.