Solution

ID: past-exam-of-the-theoretical-physics-ii-course-of-the-university-of-cambridge/2013/paper-1/4/d/solution

At coincident points the Gaussian expression has . Its six contributions give
When all mutual separations become large and the density stays the same nonzero , only remains. Consequently
The bosonic value is from Gaussian exchange pairings; the fermionic determinant vanishes when its rows coincide. Density-normalized correlations avoid the additional homogeneity assumption. For a specified bosonic number product, part (c)'s occupation sum must replace the six-pairing formula, so neither the universal factor six nor a universal printed ratio follows from that specification alone.

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