No, electron neutrinos are not considered to be tachyons. Tachyons are hypothetical particles that travel faster than the speed of light, while electron neutrinos have been observed to have a finite mass and travel at the speed of light.
The paper "1408.2804v7" is a scientific research paper that explores the possibility of electron neutrinos being tachyons. It presents a theoretical framework and analysis of existing data to investigate this question.
As indicated by the "v7" in the title, there have been 7 versions of the paper "1408.2804" published. This is common in scientific research as new data and insights may lead to revisions and updates of the original paper.
The numbers "1408.2804" in the title of the paper refer to the arXiv identifier, a digital repository for scientific papers. This identifier helps to identify and locate the paper online.
The current consensus among experts is that electron neutrinos are not tachyons. While the paper "1408.2804v7" presents a theoretical framework for investigating this question, it has not been widely accepted by the scientific community and further research and evidence is needed to support the claim.