Have superluminal claims been put to rest?

OPERA physics co-ordinator Dario Autiero resigned on Friday. (Courtesy: CERN)

By Tushna Commissariat

Following my blog last Friday afternoon about the resignation of OPERA spokesperson Antonio Ereditato, it emerged later that evening that OPERA’s physics co-ordinator Dario Autiero, from the Institute of Nuclear Physics in Lyon, France, had also resigned. Nature reported that Autiero felt that tensions within the OPERA collaboration that had always existed were becoming impossible to resolve and that the media attention about superluminal neutrinos added fuel to the fire.

On Saturday, Ereditato broke his silence and wrote a long public statement about his resignation in a letter to the editor of Le Scienze, the Italian edition of Scientific American. In it, he says that words such as “‘errors’, ‘mistakes’ and ‘flop’ were bandied about regarding what in actual fact is standard scientific procedure in experimental work” and that “it is no accident that the word ‘error’ has a completely different meaning in scientific method than it does in common parlance”. He too points towards media attention, saying that “the message [of the results from the first press conference] was excessively sensationalized and portrayed with not always justified simplification” and that the “enormous media interest” put unexpected pressures on the entire collaboration. You can read his entire statement here.

Coincidently or not, the OPERA collaboration held a mini workshop on Friday evening at the Gran Sasso lab that was streamed live online. The “LNGS results on the neutrino velocity topic” workshop included a further analysis of the two errors that led to the superluminal results.

Slides and PDFs of some of the presentations are available online. One of the talks, entitled “Measurements and cross checks on OPERA timing equipments”, was given by G Sirri from INFN Bologna on behalf of the OPERA collaboration. His slides indicate that a connector for a fibre-optic cable that was incorrectly plugged in definitely contributed towards the error. But the cable error alone would have been much larger than the observed error, which perhaps would have led the researchers to find the result implausible. The other error that occurred – a problem with one of OPERA’s oscillators that led to a “time-stamp drift” – caused the neutrino time of flight that was recorded to be longer than the actual travel time. The unfortunate combination of these two “opposing” errors meant that the final result of the neutrinos travelling at a velocity 20 parts per million above the speed of light was an almost believable result. While there has been no official statement from OPERA regarding this just yet, it seems that the mystery of the superluminal neutrinos has been put to rest.