Log to log-log crossover of entanglement in a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mn>1</mml:mn><mml:mo>+</mml:mo><mml:mn>1</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math> -dimensional massive scalar field

We study three different measures of quantum correlations---entanglement spectrum, entanglement entropy, and logarithmic negativity---for a ($1+1$)-dimensional massive scalar field in flat space-time. The spectrum for the discretized ground state indicates crossover zero-mode regime, which is further substantiated by an analytical treatment both entropy negativity. exact nature this depends on boundary conditions used---the leading order term switches from log to log-log behavior periodic Neumann conditions. In contrast, Dirichlet, it parameters within that are switched. show manifests as change divergent negativity close limit. thus two regimes have fundamentally information content. Furthermore, analysis ground-state fidelity shows us region between critical point $\mathrm{\ensuremath{\Lambda}}=0$ dominated effects, featuring explicit dependence IR cutoff system. For reduced single oscillator, we occurs $Na{m}_{f}\ensuremath{\sim}\ensuremath{\mathcal{O}}(1)$.