A neutral particle

PHYSICS · Multi-part · Fermi University Physics · Particle Physics & Quantum Fields · Particles, interactions and experiment · Particles, interactions and experiment

Particle Physics, Ch Hadrons: baryons, mesons and their quark content

Problem

A neutral particle, which leaves no track, decays at a point

L = 5.7\,\mathrm{cm}

from where it was produced (laboratory frame) into two charged tracks, one identified from its curvature and energy loss as a proton and the other as a negative pion. Their measured energies sum to

E_{\text{tot}} = 1372.9\,\mathrm{MeV}

, and the vector sum of their momenta has magnitude

|\mathbf{p}_{\text{tot}}|c = 800\,\mathrm{MeV}

. ((a)) Find the invariant mass

Mc^2

of the parent particle. ((b)) Find the proper time

t_0

this parent lived before decaying, measured in its own rest frame. ((c)) State which interaction is responsible for the decay and name the parent particle, its quark content and its strangeness.

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