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Résumé |
We now have pretty good approximations to the ground state (true vacuum) of
interacting quantum field theories in 1+1 dimensions (for example with continuous
tensor networks). However, it's not easy to get excited states or real time
correlation functions with these continuous methods. From the ground state, it is
easy to compute to exquisite precision vacuum correlation functions at equal time.
Since they can be estimated precisely, this brings a natural question: can we use
them to extract information about the excited states and real-time correlation
functions that we do not easily approximate directly? I will show that this
estimation problem is easy to formulate as a linear program. Solving it gives
bounds on the spectral function and real time correlation functions, assuming we
know the errors on our equal-time correlation functions. I'll show this can be
combined with a scanning approach to precisely estimate the mass gap. |
