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by feider
3656 days ago
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"New particle is not included in the Standard Model--because there hasn't been any experimental evidence for one.." What?! That statement is absurd - reminds me the story of how geocentric model was "adjusted" when new measurements came along. That just leads to overfitting a model. The property of a sound theory is that it can predict future data; it does not just rationalize on data already acquired. |
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My phrasing evidently did not make my point clear. The SM has been known to be an approximation (the usual term is "effective field theory") for several decades; and furthermore, there are well-understood reasons why that particular model is a good approximation up to a certain point. None of that changes if and when we discover experimental evidence of new particles not included in the SM (as we might now have done); in particular, the structure of the SM itself will not change. What changes is that now we have (hopefully) some evidence to help us build the theory at the next level down, the theory to which the SM is an approximation.
That process will not consist of adding parameters to the existing SM (which would be "overfitting"). It will consist of building a new model and then showing how the current SM arises as an approximation in the new model. If we had had this evidence several decades ago, what we now call the "Standard Model" would be that new model instead of the one we currently call the "Standard Model"; we could have jumped to the next level then instead of having to wait.