A Search for Correlated Low-energy Electron Antineutrinos in KamLAND with Gamma-Ray Bursts

Abstract

We present the results of a time-coincident event search for low-energy electron antineutrinos in the KamLAND detector with gamma-ray bursts (GRBs) from the Gamma-ray Coordinates Network and Fermi Gamma-ray Burst Monitor. Using a variable coincidence time window of ±500 s plus the duration of each GRB, no statistically significant excess above the background is observed. We place the world’s most stringent 90% confidence level upper limit on the electron antineutrino fluence below 17.5 MeV. Assuming a Fermi–Dirac neutrino energy spectrum from the GRB source, we use the available redshift data to constrain the electron antineutrino luminosity and effective temperature.

A Review of Searches for Evidence of Tachyons

“…However, Ellis et al [52] argued that the significance of Huang and Ma's result is overstated because it depends on cross-correlating sub-MeV and multi-GeV photons from GRBs, which is risky given the paucity of multi-GeV photons from these occurrences. Casting further doubt on the Huang-Ma result, a search for low-energy (E < 17.5 MeV) neutrinos associated with GRBs (within a time window of ±500 s) in the KamLAND detector has yielded no candidates above background [53]. In summary, like the Liao-Marfatia analysis, that by Huang and Ma cannot be said to have yet provided definitive evidence for superluminal neutrinos or for violations of CPT or Lorentz invariance.…”

KamLAND’s search for correlated low-energy electron antineutrinos with astrophysical neutrinos from IceCube

“…Given the maximum expected time-of-flight delay, we choose to define the minimal time window used in this analysis to be (a) 𝑡 𝑝 = 500 s. This is a commonly adopted time window range used for similar analyses that search for correlated neutrinos with gravitational waves [49][50][51] and gamma-ray bursts (GRB) [36,52,53]. Since there are some cosmological events that span more than 1000 s, such as the longest duration GRBs, we also use several more conservative time windows of 𝑡 𝑝 = 1000 s (b), 3600 s (c), and 10 000 s (d).…”