A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS

TL;DR

This study analyzes ICARUS data to test for superluminal neutrinos and finds no evidence supporting faster-than-light travel, thereby refuting the Cherenkov radiation analogy predicted by some theories.

Contribution

The paper provides the first experimental limit on superluminal neutrino speeds using ICARUS data, challenging previous claims of superluminal propagation.

Findings

No superluminal Cherenkov-like events observed in ICARUS data.

Limits on neutrino superluminality set at delta < 2.5 x 10^-8.

Results are consistent with neutrinos traveling at or below the speed of light.

Abstract

The OPERA collaboration has claimed evidence of superluminal {\nu}{_\mu} propagation between CERN and the LNGS. Cohen and Glashow argued that such neutrinos should lose energy by producing photons and e+e- pairs, through Z0 mediated processes analogous to Cherenkov radiation. In terms of the parameter delta=(v^2_nu-v^2_c)/v^2_c, the OPERA result implies delta = 5 x 10^-5. For this value of \delta a very significant deformation of the neutrino energy spectrum and an abundant production of photons and e+e- pairs should be observed at LNGS. We present an analysis based on the 2010 and part of the 2011 data sets from the ICARUS experiment, located at Gran Sasso National Laboratory and using the same neutrino beam from CERN. We find that the rates and deposited energy distributions of neutrino events in ICARUS agree with the expectations for an unperturbed spectrum of the CERN neutrino beam. Our results therefore refute a superluminal interpretation of the OPERA result according to the Cohen and Glashow prediction for a weak current analog to Cherenkov radiation. In particular no superluminal Cherenkov like e+e- pair or gamma emission event has been directly observed inside the fiducial volume of the "bubble chamber like" ICARUS TPC-LAr detector, setting the much stricter limit of delta < 2.5 10^-8 at the 90% confidence level, comparable with the one due to the observations from the SN1987A.