I am new to this topic, so I do not have much knowledge of these. When discussing vacuum instability in QFT, higgs self-coupling becoming negative at high-energy scale when renormalized is said to indicate a problem.
Does this cause some calculation/theoreticl problems other than vacuum instability?
Why and how does vacuum instability rise out of Higgs self-coupling becoming negative? QFT calculations are done assuming some vacuum, so I wonder what this is supposed to mean.