In this talk, I will present a novel strategy to fit experimental data focusing on pi-pi scattering. The fit strategy requires using S-matrix Bootstrap and non-convex optimization methods. Using this procedure, we numerically constructed a full-fledged scattering amplitude that fits the data and contains the known QCD spectrum up to 1.4 GeV.  Surprisingly, Bootstrap predicts an additional tetraquark state, not yet observed, and that is being investigated in the decay of the B+ -> pi+ p+ pi- at LHCb.
 
This talk is based on https://arxiv.org/abs/2410.23333.


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https://zoom.us/j/98965732714