Returns the combined mass of the particles represented in the provided MomentumArray.

This is done by summing the four momenta, optionally weighting the components, and then taking the inner product of the result with itself in Minkowski space.

Parameters:¶

pmu : MomentumArray or ndarray[void]¶

Momenta of particles comprising a jet, or an analagous combined object. If a numpy array is passed, it must be structured with fields with names ('x', 'y', 'z', 'e').

weight : ndarray[float64], optional¶

Weights for each particle when reconstructing the jet momentum. May be either structured or unstructured. If unstructured, ensure the columns are in the order ('x', 'y', 'z', 'e').

Notes

This does not mask the MomentumArray for you. All filters and cuts must be applied before passing to this function.

In the event of a squared mass below zero (due to numerical fluctuations for very low mass reconstructions), this function will simply return 0.0.