= Momentum distribution
A <momentum distribution> describes the <statistical weight> of particle momenta, with its normalization stated. A one-particle distribution $n(p)$ can be normalized to one as a <probability density> or to the <particle number>; these conventions differ by a factor.
For a <pure state> with momentum-space wavefunction $\widetilde\psi(p)$, the <probability density> is $|\widetilde\psi(p)|^2$ under the chosen Fourier normalization. In many-body systems, the <one-body density matrix> determines the single-particle <momentum> occupation. A narrow <momentum> peak can indicate coherence, but finite size, interactions and the <measurement> protocol also affect the observed profile.
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